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HARVARD UNIVERSITY e Library of the
Museum of
Comparative Zoology
is eS
The CANADIAN FIELD-NATURALIST
Published by THE OTTAWA FIELD-NATURALISTS’ CLUB, Ottawa, Canada
< . 2
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ars
January-March 1992
Volume 106, Number 1
The Ottawa Field-Naturalists’ Club
FOUNDED IN 1879
Patron His Excellency The Right Honourable Ramon John Hnatyshyn, P.C., C.C., C.M.M., Q.C., Governor General of Canada The objectives of this Club shall be to promote the appreciation, preservation and conservation of Canada’s natural heritage; to encourage investigation and publish the results of research in all fields of natural history and to diffuse infor-
mation on these fields as widely as possible; to support and cooperate with organizations engaged in preserving, maintain- ing or restoring environments of high quality for living things.
Honorary Members
Edward L. Bousfield Clarence Frankton Don E. McAllister Hugh M. Raup Irwin M. Brodo Claude E. Garton Stewart D. MacDonald Loris S. Russell William J. Cody W. Earl Godfrey Verna Ross McGiffin ~ Douglas B.O. Savile William G. Dore C. Stuart Houston Hue N. MacKenzie Pauline Snure R. Yorke Edwards Louise de K. Lawrence Eugene G. Munroe Mary E. Stuart Anthony J. Erskine Thomas H. Manning Robert W. Nero Sheila Thomson 1992 Council President: Frank Pope Ronald E. Bedford Ellaine Dickson Vice-President: Michael Murphy Barry Bendell Enid Frankton Recording Secretary: Connie Clark Fenja Brode Cor Gaskell ; ; Steve Blight Bill Gummer Corresponding Secretary: Eileen Evans Lee Cairnie Jeff Harrison Treasurer: Gillian Marston Martha Camfield Linda Maltby William J. Cody Jack Romanow Francis R. Cook Doreen Watler Don Cuddy Ken Young
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Most back numbers of this journal and its predecessors, Transactions of The Ottawa Field-Naturalists’ Club, 1879-1886, and The Ottawa Naturalist, 1887-1919, and Transactions of The Ottawa Field-Naturalists’ Club and The Ottawa Naturalist — Index compiled by John M. Gillett, may be purchased from the Business Manager.
Cover: Left: Portion of Hog’s Back prairie and savanna, a remnant of the Rice Lake Plains near Alderville, Ontario. Right: Wild Lupine, Lupinus perennis, a rare species in Ontario, once abundant on the Rice Lake Plains, this plant part of a relict population near Harwood, Ontario. Photos by P. M. Catling. See article by P. M. Catling, V.R. Catling and S. M. McKay-Kuja on the Extent and Floristic Composition of the Rice Lake Plains, pages 73-86.
MCZ LIBRARY/ JAN 25 1993
HARVARD UNIVERSITY THE CANADIAN
FIELD-NATURALIST
Volume 106
1992
THE OTTAWA FIELD-NATURALISTS’ CLUB
OTTAWA CANADA
The Canadian Field-Naturalist
January—March 1992
Volume 106, Number 1
Rare and Endangered Fishes and Marine Mammals of Canada: COSEWIC Fish and Marine Mammal Subcommittee Status Reports VII.
R. R. CAMPBELL
Department of Fisheries and Oceans, 200 Kent Street, Ottawa, Ontario K1A OE6 Present address: Administrator, Convention on International Trade in Endangered Species, Canadian Wildlife Service, Ottawa, Ontario K1A 0H3
Campbell R. R. Editor. 1992. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammal Subcommittee Status Reports VIII. Canadian Field-Naturalist 106(1): 1-6.
Eight status reports representing those species of fish and marine mammals which were assigned status at the 1991 COSEWIC General Meeting have been prepared for publication. Committee and Subcommittee (Fish and Marine Mammal) activities are briefly discussed. Updated lists of status assignments for fish and marine mammals and for species which are currently under consideration or yet to be considered are presented in tabular form.
Huit rapports sur le statut des poissons et des mammiféres marins auxquells un statut a été attribué a la réunion du CSEMDC en 1991 ont été préparés pour publication. Les activités du Comité et du sous-comité (poissons et mammiféres marins) sont briévement discutées. Les listes a jour des espéces de poissons et de mammiféres marins sur lesquelles déja on
a Statées, ainsi que les sont présentées sous forme tabulaire.
Key Words: Rare and Endangered species, fish, marine mammals, COSEWIC.
As indicated in previous submissions (Campbell 1984-1991), the intent of the Subcommittee on Fish and Marine Mammals is to publish the status reports (on those species of fish and marine mammals) which the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has reviewed, ap- proved, and used as a basis for the assignment of status to species in jeopardy in Canada. The group of eight reports presented herein represent the fish and marine mammal component of those species assigned status in 1991. It is hoped that we will have the continuing support of the Department of Fisheries and Oceans to offer, in succeeding vol- umes, those reports reviewed in future years (Table 1 presents those species assigned status to April 1991).
Progress
COSEWIC has undertaken to make public, sup- porting information on each species classified (see Cook and Muir 1984). The Fish and Marine Mammal Subcommittee has been able to use this journal as one step in achieving the goal [see Canadian Field-Naturalist 98(1): 63-133; 99(3): 404450; 102(1): 81-176, 102(2): 270-398; 103(2): 147-220; 104(1): 1-138; 105(2): 151-293] and the
encouraging response to these publications has enabled us to continue.
Contributions to the Committee of $10 000 made by the Department of Fisheries and Oceans and Environment Canada in 1990 were once again matched by World Wildlife Fund Canada. These per- mitted the contracting of several (12) new reports in 1990. Although there are a considerable number of reports in preparation or under review, the number of species still awaiting consideration has been reduced to three (Table 3) and contracts are being prepared for the production of reports on these.
There are currently 41 status reports on fish species and 15 on marine mammal species under review or in preparation (Table 2), several will be assigned status in 1992. In addition to soliciting fur- ther status reports on species of concern, the Subcommittee continues to obtain updated reports on the status of selected species as new information becomes available.
As a result of the addition of the Harbour Por- poise to the threatened list, the Department of Fisheries and Oceans has initiated efforts for the conservation of the species. A recovery team has been established and a recovery plan for the stocks in, at least, the Canadian portion of the range should soon be available. Team membership includes rep-
THE CANADIAN FIELD-NATURALIST
Vol. 105
TABLE 1. Fish and Marine Mammal Species with Assigned COSEWIC Status to April 1991.
Species
Fish
Lake Sturgeon
Bloater
Blueback Herring
Hornyhead Chub
River Chub
Redfin Shiner
Leopard Dace
Golden Redhorse
Mountain Sucker
Least Darter
River Darter
Green Sunfish
Longear Sunfish
Spoonhead Sculpin
Brook Silverside
Y-Prickleback
Darktail Lamprey
Bering Cisco
Pixie Poacher*
Vancouver Lamprey*
Chestnut Lamprey
Northern Brook Lamprey
Green Sturgeon
Shortnose Sturgeon
White Sturgeon
Spotted Gar
Kiyi
Squanga Whitefish®
Pacific Sardine
Silver Chub
Umatilla Dace
Bigmouth Shiner
Pugnose Shiner
Silver Shiner
Pugnose Minnow
Redside Dace
Speckled Dace
Central Stoneroller
Banded Killifish (Newfoundland)
Blackstripe Topminnow
Bigmouth Buffalo
Black Buffalo
Spotted Sucker
River Redhorse
Greenside Darter
Brindled Madtom
Orangespotted Sunfish
Redbreast Sunfish
Fourhorn Sculpin (Arctic Islands)
Giant Stickleback*
Unarmoured Stickleback
Blackline Prickleback
Bering Wolffish
Lake Simcoe Whitefish*
Blackfin Cisco
Shortnose Cisco
Shortjaw Cisco
Deepwater Sculpin (Great Lakes Watershed)
Black Redhorse
Scientific Name
Acipenser fulescens Coregonus hoyi
Alosa aestivalis
Nocomis biguttatus Nocomis micropogon Lythrurus umbratilis Rhinichthys falcatus Moxostoma erythrurum Castostomus platyrhynchus Etheostoma microperca Percina shumardi Lepomis cyanellus Lepomis megalotis Cottus ricei
Labidesthes sicculus Allolumpenus hypochromus Lethenteron alaskense Coregonus laurettae Occella impi
Lampetra macrostoma Ichthyomyzon castaneus Ichthyomyzon fossor Acipenser medirostris Acipenser brevirostrum Acipenser transmontanus Lepisosteus ocultus Coregonus kiyi Coregonus sp.
Sardinops sagax Macrhybopsis storeriana Rhinichthys umatilla Notropis dorsalis Notropis anogenus Notropis photogenis Opsepocodus emiliae Clinostomus elongatus Rhinichthys osculus Campostoma anomalum Fundulus diaphanus Fundulus notatus Ictiobus cyprinellus Ictiobus niger Minytrema melanops Moxostoma carinatum Etheostoma blennioides Notorus miurus
Lepomis humilus Lepomis auritus Myoxocephalus quadricornis Gasterosteus sp. Gasterosteus sp. Acantholumpenus mackayi Anarichus orientalis Coregonus clupeaformis spp. Coregonus nigripinnis Coregonus reighardi Coregonus zenithicus
Myoxocephalus thompsoni Moxostoma dusquesnei
Status
RANSDR? RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RANSDR RAISIFSD> RAISIFSD RAISIFSD Vulnerable! Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Vulnerable Threatened Threatened Threatened Threatened
Threatened Threatened
Date Assigned
April 1986 April 1988 April 1980 April 1988 April 1988 April 1988 April 1990 April 1989 April 1991 April 1989 April 1989 April 1987 April 1987 April 1989 April 1989 April 1991 April 1990 April 1991 April 1991 April 1986 April 1991 April 1991 April 1987 April 1980 April 1990 April 1983 April 1987 April 1988 April 1987 April 1985 April 1988 April 1985 April 1985 April 1983° April 1985 April 1987 April 1980! April 1985 April 1989 April 1985 April 1989 April 1989 April 1983 April 1983° April 1990 April 1985 April 1989 April 1989 April 1989 April 1980 April 1983 April 1989 April 1989 April 1987 April 1988 April 1987 April 1987
April 1987 April 1988
Continued
199] CAMPBELL: RARE AND ENDANGERED FISHES AND MARINE MAMMALS
TABLE 1. Concluded
Species Scientific Name Status Date Assigned Copper Redhorse*® Moxostoma hubbsi Threatened April 1987 Margined Madtom Noturus insignis Threatened April 1989 Enos Lake Stickleback® Gasterosteus sp. Threatened April 1988 Shorthead Sculpin Cottus confusus Threatened November 1983 Aurora Trout® Salvelinus fontinalis timagamiensis Endangered April 1987 Acadian Whitefish® Coregonus huntsmani Endangered April 1983 Salish Sucker Catostmus sp. Endangered April 1986 Gravel Club Erimystax x-punctata Extirpated April 19878 Paddlefish Polyodon spathula Extirpated April 1987 Deepwater Cisco Coregonus johannae Extinct April 1988 Longjaw Cisco Coregonus alpenae Extinct April 1988 Banff Longnose Dace Rhinichthys cataractae smithi Extinct April 1987 Blue Walleye Stizostedion vitreum glaucum Extinct April 1985 Marine Molluscs Northern Abalone Haliotis kamtschatkana N/A? April 1988 Marine Mammals California Sea Lion Zalophus californianus RANSDR April 1987 Steller Sea Lion Eumetopias jubatus RANSDR April 1987 Atlantic Walrus Odobenus rosmarus rosmarus
Eastern Arctic RANSDR April 1987
Northwest Atlantic Extirpated April 1987 Grey Whale Eschrichtius robustus
Northeast Pacific RANSDR April 1987
Northwest Atlantic Extirpated April 1987 Hooded Seal Cystophora cristata RANSDR April 1986 Northern Elephant Seal Mirounga angustirostris RANSDR April 1986 Ringed Seal Phoca hispida RANSDR April 1989 Risso’s Dolphin Grampus griseus RANSDR April 1990 Northern Right Whale Lissodelphis borealis RANSDR April 1990 Pacific White-sided Dolphin Lagenorhynchus obliquidens RANSDR April 1990 Dall’s Porpoise Phocoenoides dalli RANSDR April 1989 Narwhal Monodon monoceros RANSDR April 1986° Blainville’s Beaked Whale Mesoplodon densirostris RANSDR April 1989 Cuvier’s Beaked Whale Ziphius cavirostris RANSDR April 1990 Hubb’s Beaked Whale Mesoplodon carlhubbsi RANSDR April 1989 Stejneger’s Beaked Whale Mesoplodon stejnegeri RANSDR April 1989 True’s Beaked Whale Mesoplodon mirus RANSDR April 1989 False Killer Whale Pseudorca crassidens RANSDR April 1990 Atlantic White-sided Dolphin Lagenorhynchus acutus RANSDR April 1991 Common Dolphin Delphinus delphis RANSDR April 1991 Beluga Delphinapterus leucas
Beaufort Sea RANSDR April 1986
St. Lawrence River Endangered April 1983
Eastern Hudson Bay Threatened April 1988
Ungava Bay Endangered April 1988
S.E. Baffin Island Endangered April 1990 Sowerby’s Beaked Whale Mesoplodon bidens Vulnerable April 1989 Blue Whale Balaenoptera musculus Vulnerable April 1983 Fin Whale Balaenoptera physalus Vulnerable April 1987! Sea Otter Enydra lutris Endangered May 1978) Harbour Porpoise Phocoena phocoena
Northwest Pacific RAISIFSD April 1991
Northeast Atlantic Threatened April 1990 Humpback Whale Megaptera novaeangliae
Northeast Pacific Threatened April 1982!
Northwest Atlantic Vulnerable April 1985 Bowhead Whale Balaena mysticetus Endangered April 1980! Right Whale Eubalaena glacialis Endangered April 1980* Sea Mink Mustela macrodon Extinct April 1985
4 THE CANADIAN FIELD-NATURALIST Vol. 105
“ RANSDR — Use of NIAC (Not in Any Category) dropped in 1988 and subsequently converted. RANSDR is not a cate- gory = Report Accepted No Status Designation Required.
> RAISIFSD — the use of a new list “Report Accepted Insufficient Scientific Information For Status Designation” was approved at the 1990 General Meeting.
© Endemic to Canada
4 Vulnerable — “Rare” category changed to “Vulnerable” in 1988. Dates Assigned of 1988 or earlier indicate date of origi- nal Rare status assignment. These were subsequently converted to Vulnerable at the 1990 General Meeting based on the advice of the Fish and Marine Mammal Subcommittee.
© Updated April 1987 — no status change.
* Updated April 1984 — no status change.
& Updated April 1987 — previous status of “Endangered” assigned April 1985.
» N/A — Status Not Assigned. COSEWIC has no mandate for invertebrates. Report accepted and recommended RANSDR Status agreed to, but not assigned.
i Updated April 1986 — no status change.
} Updated April 1985 — North Atlantic stock downlisted to ‘Vulnerable’
K Updated April 1985 and April 1990 — no status change.
TABLE 2. Fish and Marine Mammal Species for which Status Reports are in preparation, or under review, April 1991
Species Scientific Name Proposed Status Fish
Atlantic Sturgeon Acipenser oxyrhynchus ? Lake Sturgeon® Acipenser fulvescens ?
Red (Arctic) Char!
Salvelinus alpinus spp.
? (Landlocked populations: Quebec, New Brunswick, Newfoundland
Atlantic Salmon Salmo salar z
Bull Trout Salvelinus confluentus Vulnerable
Spring Cisco* Coregonus sp. ?
Lake Herring Coregonus artedi Endangered — Lakes Erie, Ontario Lake Whitefish Coregonus clupeaformis Threatened — Lakes Erie, Ontario Mira Whitefish Coregonus sp. Vulnerable
Opeongo Whitefish* Coregonus sp. Threatened
Round Whitefish Prosopium cylindraceum Vulnerable — Lakes Huron, Ontario Pygmy Whitefish Prosopium coulteri ?
Pygmy Smelt Osmerus spectrum Vulnerable
Chain Pickerel Esox niger Vulnerable
Grass Pickerel Esox americanus vermiculatus Vulnerable
Redfin Pickerel Esox americanus americanus Vulnerable
Blackchin Shiner Notropis heterodon Vulnerable
Bluntnose Minnow Pimphales notatus Vulnerable (Manitoba) Chiselmouth Acrocheilus alutaceus Vulnerable (British Columbia)
Cutlips Minnow
Exoglossum maxillingua
Vulnerable
Eastern Silvery Minnow Hybognathus nuchalis regius Vulnerable
Ghost Shiner Notropis buchanani Vulnerable Roseyface Shiner Notropis rubellus Vulnerable
Striped Shiner Luxilus chrysocephalus Vulnerable
Weed Shiner Notropis texanus Vulnerable (Manitoba) Western Silvery Minnow Hybognathus argyritis ? (Alberta)
Lake Chubsucker Erimyzon sucetta Vulnerable
Jasper Longnose Sucker* Castostomus castostomus lacustris Vulnerable Warmouth Lepomis gulosus Vulnerable
Striped Bass Morone saxatilis Endangered Channel Darter Percina copelandi Vulnerable
Eastern Sand Darter Ammocrypta pellucida Vulnerable Tessellated Darter Etheostoma olmstedi Vulnerable Flathead Catfish Pylodictis olivaris ? Northern Madtom Noturus stigmosus Vulnerable
Continued
1991
TABLE 2. Concluded
CAMPBELL: RARE AND ENDANGERED FISHES AND MARINE MAMMALS 5
Species Scientific Name Proposed Status
Texada Stickleback* Gasterosteus sp Vulnerable
Cultus Pygmy Coastrange Sculpine Cottus aleuticus Threatened (British Columbia) Mottled Sculpin Cottus bairdi Vulnerable (British Columbia, Alberta) Shorthead Sculpin® Cottus confusus Vulnerable
Spinynose Sculpin Asemichthys taylori Vulnerable
Bluefin Tuna Thunnus thynnus ?
Marine Mammals
White-beaked Dolphin Lagenorhynchus albirostris 2
Baird’s Beaked Whale Beluga Whale (W. Hudson Bay) Northern Bottlenose Whale
Berardius bairdii
Delphinapterus leucas Hyperoodon ampullatus ?
Bowhead Whale® Balaena mysticetus Endangered
Killer Whale Orcinus orca ? Long-finned Pilot Whale Globicephela malaena ? Sperm Whale Physeter catadon ? Striped Dolphin Stenella coeruleoalba ? Bottlenose Dolphin Tursiops truncatus ? Short-finned Pilot Whale Globicephala macrorhynchus Vulnerable
Pygmy Sperm Whale Kogia breviceps Vulnerable
Sei Whale Balaenoptera borealis ? Minke Whale Balaenoptera acutorostrata ? Dwarf Sperm Whale Kogia simus Vulnerable
*Endemic to Canada = ° Updated Status Report
INot of immediate concern
TABLE 3. Fish and Marine Mammal Species of Interest to COSEWIC — April 1991 (Not listed by priority)
Species Scientific Name
Fish
Pygmy Longfin Smelt* Spirinichus thaleichthys Nooky Dace Rhinichthys cataractae spp.
Liard Hotspring Lake Chub*
*Endemic to Canada
resentation from the United States and there is no doubt that ultimately recovery plans should be inter- national in character.
Acknowledgments
The Subcommittee wishes to extend their thanks to the various authors who have so generously con- tributed their time and talent in support of COSEWIC, and I wish also to thank the members of the Subcommittee for their unstinting efforts in reviewing the reports and for their helpful com- ments.
The Subcommittee is grateful to World Wildlife Fund Canada, the Canadian Wildlife Service, and the Canadian Museum of Nature (formerly the National Museum of Natural Sciences) for their assistance in the process. A special mention to Francis Cook and The Canadian Field-Naturalist for assistance in pub- lication and editing, and to all members of
Couesius plumbeus spp.
Proposed Status
Vulnerable (landlocked population in Harrington Lake, British Columbia)
Vulnerable (British Columbia)
Vulnerable (British Columbia’s Liard Hotspring)
COSEWIC for their dedication and interest in the future of Canada's fauna and flora. We also grateful- ly acknowledge the financial and secretarial support provided through the Department of Fisheries and Oceans and the financial contribution of Fisheries and Oceans, Environment Canada, and World Wildlife Fund Canada which has permitted the pro- duction of several new reports.
Literature Cited
Campbell, R. R. 1984. Rare and Endangered fish of Canada: The Committee on the Status of Endangered Wildlife in Canada: (COSEWIC) Fish and Marine Mammal Subcommittee. Canadian Field-Naturalist 98(1): 71-74.
Campbell, R. R. 1985. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammals Subcommittee Reports: II. Canadian Field-Naturalist 99(3): 404-408.
6 THE CANADIAN FIELD-NATURALIST
Campbell, R. R. 1987. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammals Subcommittee Reports: II]. Canadian Field-Naturalist 101(2): 165-170.
Campbell, R. R. 1988. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammals Subcommittee Reports: [V. Canadian Field-Naturalist 102(1): 81-86.
Campbell, R. R. 1989. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammals Subcommittee Reports; V. Canadian Field-Naturalist 103(2): 147-157.
Campbell, R. R. 1990. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammals Subcommittee Reports: VI. Canadian- Field Naturalist 104(1): 1-6.
Vol. 105
Campbell, R. R. 1991. Rare and endangered fish and marine mammals of Canada: COSEWIC Fish and Marine Mammals Subcommittee Reports: VII. Canadian Field-Naturalist 105(2): 151-156.
Cook, F. R., and D. Muir. 1984. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC): History and progress. Canadian Field-Naturalist 98(1): 63-70.
Reeves, R. R., and E. Mitchell. 1989. Status of White Whales (Delphinapterus leucas) in Ungava Bay and eastern Hudson Bay. Canadian Field-Naturalist 103(2): 220-239.
Accepted 31 May 1991
Status of the Northern Brook Lamprey, [chthyomyzon fossor, in Canada*
J. LANTEIGNE 58-2069 Jasmine Crescent, Gloucester, Ontario K1J 7W2
Lanteigne, J. 1992. Status of the Northern Brook Lamprey, Ichthyomyzon fossor, in Canada. Canadian Field-Naturalist 106(1): 7-13.
The Northern Brook Lamprey, /chthyomyzon fossor, is a small, non-parasitic lamprey not particularly abundant in its endemic North American range. In Canada, it is found in the Hudson Bay drainage of Manitoba and in the Great Lakes drainage of Ontario and Quebec. These represent the northern limits of its range. It has never been the object of a directed survey in Canada; its precise status is thus unknown. The Northern Brook Lamprey is not specifically protected in Canada except for the general protection granted through the fish protection and pollution prevention sections of the Fisheries Act. The paucity of Canadian records supports a status of vulnerable for this species.
De petite taille et non parasite, la lamproie du Nord, Ichthyomyzon fossor, n’ est pas trés abondante dans son aire de réparti- tion limitée a l’Amérique du Nord. Au Canada, elle est présente dans le bassin hydrographique de la baie d’Hudson, au Manitoba, et dans le bassin hydrographique des Grands Lacs, au Québec et en Ontario. Ces coordonnées représentent les limites septentrionales de son aire de répartition. Etant donné qu’elle n’a jamais fait l’objet d’un relevé orienté au Canada, on n’y connait pas sa situation exacte. Elle n’est pas protégée de facon précise dans les eaux canadiennes, sauf pour ce qui est d’une protection générale en vertu des articles sur la protection de |’habitat des poissons et de la prévention de la pollu- tion de la Loi sur les péches. Sa rare capture dans les eaux canadiennes indique que |’espece est vulnérable.
Key Words: Petromyzontidae, lampreys, Northern Brook Lamprey, lamproie du Nord, Ichthyomyzon fossor, vulnerable fishes.
The Northern Brook Lamprey, /chthyomyzon fos- which yielded a more homogeneous sample, sor Reighard and Cummins 1916, is a non-parasitic Morman (1979) found a range of 86 to 166 mm lamprey endemic to North America where it is (average 115 mm). The number of trunk myomeres restricted to tributaries of Hudson Bay, the Great usually varies from 51 to 54 (average 52) (Lanteigne Lakes and the Mississippi River (Lanteigne 1981). 1981) even though Hubbs and Trautman report a The six species which comprise the genus smaller range of 50 to 52 (average 51). Its body is Ichthyomyzon, probably the most primitive among definitely bicoloured: the dark slate of the back and the Northern Hemisphere lampreys (Hubbs and _ sides contrasts with the pale grey or silvery white Trautman 1937), can be grouped into three species lower parts (Vladykov 1949). The ventral surface is pairs each composed of a parasitic stem species and somewhat tinted with orange, which is particularly a non-parasitic satellite species. Thus, Jchthyomyzon noticeable in the sexually mature female where the fossor is the non-parasitic derivative of the parasitic eggs show through the body wall (Leach 1940). The stem species, [chthyomyzon unicuspis. After meta- lateral line organs are non-pigmented, a characteris- morphosis, the parasitic species feed mainly on tic which readily separates it from its parasitic stem teleost fishes for one or more years (Scott and species, Ichthyomyzon unicuspis, (Vladykov 1949). Crossman 1973) while the non-parasitic species All the disc teeth are blunt and degenerate in keeping spawn soon after transformation. All lampreys die with its non-parasitic lifestyle which is also evident
soon after spawning. in the non-functional nature of its intestine. All the es endolateral teeth, a diagnostic character, are unicus- Description pid (Figure 1).
The adult Northern Brook Lamprey can reach a total length of 161 mm [Royal Ontario Museum _ Distribution (ROM) 177687]; Hubbs and Trautman (1937) In the drainage basins of the Eastern United States reported a range of 94 to 146 mm (average 119mm) _ (Figure 2), the Northern Brook Lamprey is found in and Lanteigne (1981) gave a range of 98 to 158 mm. the Western Great Lakes basin of Wisconsin and In the streams of Michigan’s Lower Peninsula, Michigan, in the Eastern Great Lakes basin of
“Report accepted by COSEWIC and Vulnerable Status assigned 9 April 1991.
fl
8 THE CANADIAN FIELD-NATURALIST
FiGurE 1. [chthyomyzon fossor: female, 150 mm TL: Birch River, upstream of Prawda, Manitoba; May 13, 1977; J. Jyrkkanen; ROM 34264. Note blunt, degenerate and unicuspid disc teeth.
Michigan, Ohio and Pennsylvania (not present in Lake Ontario), in the Ohio basin of Illinois, Indiana, Ohio and Kentucky and in the Lower Missouri basin of Missouri where a disjunct population is found in the Ozark Uplands (Figure 3) [Pflieger 1971].
In Canada (Figure 4), the Northern Brook Lamprey occurs in the Great Lakes basin from Lake Superior to Lake Erie but appears to be absent in the Lake Ontario drainage (Scott and Crossman 1973) even though one transformed individual was cap- tured in Tosorontio Creek (49°09'N, 79°58'W) in 1974 (ROM 30543). It has been captured in the Ottawa River at Ottawa (45°28'N, 75°37'W)
[Canadian Museum of Nature (NMC) 82-0319] and —
it occurs in the St. Lawrence River down to the Nicolet River (Vladykov 1952). Its range in Canada has recently been extended further west to the Nelson River drainage of Manitoba (Jyrkkanen and Wright 1979) where it has been captured in the Whitemouth River (50°00'N, 96°00'W) and one of its tributaries, the Birch River (49°39'N, 95°47'W). This distribution represents the northern limits of the range of the Northern Brook Lamprey in North America.
Vol. 106
Protection
The Northern Brook Lamprey is not listed as endangered, threatened or of concern in North America (Williams et al. 1989). In Canada, the species is not the object of any specific legal protec- tion other than the general protection granted under habitat and pollution prevention sections of the Federal Fisheries Act. In Manitoba protection can be afforded through the provincial Endangered Species Act by regulation.
Population Sizes and Trends
No population estimates are available. In the St. Lawrence drainage of Quebec, Vladykov (1952) captured 63 adults and 849 ammocoetes between September 1946 and August 1951. The range exten- sion of the species to Manitoba concerned 14 adult specimens (Jyrkkanen and Wright 1979). Collection records from the Royal Ontario Museum and the Canadian Museum of Nature reveal the paucity of specimens from the Great Lakes drainage as well as from other Canadian localities. It was formerly pre- sent in the Lake Ontario watershed but is now absent, or considered to be extremely rare. It is pos- sibly present in a few scattered tributary creeks (Crossman and van Meter 1979) as in Tosorontio Creek. There is no indication that the species is in
Ns
FiGurE 2. Principal drainage basins of the Eastern United States where the genus Ichthyomyzon is found.
1992
FiGuRE 3. Distributional records of Ichthyomyzon fossor in Eastern United States.
danger of extinction but the state of our knowledge is such that no predictions can be made. The better fish sampling methods used in the last two or three decades, as well as the major research effort expand- ed in the Great Lakes in the wake of the sea lamprey invasion, may be in part responsible for the greater number of endemic lampreys appearing in fish col- lections. This increase should, therefore, not be viewed as a real increase in abundance.
Habitat
The ammocoetes of the Northern Brook Lamprey require a fairly soft bottom in which to make their burrows; as a rule, they are not found in firm sand or in the extremely soft mud of backwaters (Churchill 1947). In a given area with suitable bottom, they are most numerous in water 15 to 61 cm deep, amongst the vegetation. Maximum silt content and total volatile organic content of occupied sediments in an Ohio creek were 77% and 65%, respectively (Anderson and White 1988). Small ammocoetes were less tolerant of silt than large ones. The highest density of ammocoetes are usually found in the warmer sections of streams and tributaries receiving large surface flow of warm water from lakes, swamps and marshes (Morman 1979).
LANTEIGNE: STATUS OF THE NORTHERN BROOK LAMPREY 9
In Quebec, adult Northern Brook Lampreys are found in brooks tributary to small rivers. In the Yamaska River, where it was most abundant at St. Césaire where the river spans from 30 to 130 m, the current was moderate, the water was turbid and the banks were composed of clay (Vladykov 1952). In the Lake Superior watershed, Ichthyomyzon fossor was most common in medium-to-large streams with average summer flows of 0.3 to 28.3 cubic meters per second (Schuldt and Goold 1980). It was also common in several turbid streams. Along the west- ern half of the United States shoreline, the preferred streams were generally warmer than eastern streams. In the lower peninsula of Michigan, the Northern Brook Lamprey was rarely found in small stream systems; it was most frequently collected in small, isolated segments of moderate-sized to large streams characterized by summer low flows (Morman 1979). It typically lived in the warmer, less rapid lower reaches of streams and tributaries that received large surface flow of warm water from lakes, swamps or marshes. It was also less commonly found in cold- water environments where mean daily temperatures during mid-June to August ranged from 14° to 20°C. In Manitoba, Ichthyomyzon fossor has been collected in the Birch River, a tributary of the Winnipeg River (Jyrkkanen and Wright 1979). The Birch River is a small river with a maximum flow of 5.7 to 8.5 cubic meters per second (cm/s) and a low flow of less than 0.15 cm/s. The substrate is highly varied with silts and sediments in the quieter reaches of the stream, gravel and cobble riffles and several small water- falls.
In the Yamaska River of Quebec, the Northern Brook Lamprey spawned in May when the water temperature ranged from 12.8° to 17.2°C. Spawning activity peaked at water temperatures of 13.3° to 15.6°C (Vladykov 1949). In Michigan, spawning activities were observed from 23 May to 27 May and were most vigorous at water temperatures ranging from 20° to 22°C; spawning seldom took place at water temperatures inferior to 18°C (Reighard and Cummins 1916). All the spawners were observed on a bottom of coarse gravel and shingle which con- tained stones from 2.5 to 15.2 cm in diameter, and in water from 20.3 to 45.7 cm deep. At that point, the stream was less than 10 m wide with a strong current (Reighard and Cummins 1916).
General Biology Reproductive Capability
Like all lampreys, the Northern Brook Lamprey breeds only once. According to Leach (1940), the ammocoete period lasts six years and is followed by a short transformation period of two or three months and an immature adult period of a semi-sedentary nature. The latter lasts until mid-February. The active early adult period follows and leads to sexual
10 THE CANADIAN FIELD-NATURALIST
Vol. 106
FiGuRE 4. Distribution records of Ichthyomyzon fossor in Canada.
maturity around mid-May. The post-spawning period probably lasts only a few days, after which all spawners die. Since degeneration of the alimentary canal occurs at the beginning of transformation, there is a period of eight or nine months during which no food is taken (Churchill 1947).
Three physical factors in streams are essential for successful spawning: first, for nest building, a suit- able substrate of gravel is required that includes at least a small amount of silt-free sand or other fine material to which the eggs can adhere, thereby increasing the probability of their retention in the nest. Second, a current must be flowing uni-direc- tionally over the nest. Third, the water temperatures must be suitable.
In Manitoba, fourteen mature individuals were cap- tured in the Birch River in mid-May 1977 (Jyrkkanen and Wright 1977). Of these, 10 were males and four were females. They were assumed to be spawning at the time of collection. No details on the reproductive behavior were reported. Two more sexually mature individuals, a male and a female whose eggs were free in the body cavity, were captured in the Whitemouth River (into which the Birch River empties) in mid-
July 1977 (Lanteigne 1981). For two nests in which -
sex ratio was determined in a Michigan river, 11 males and two females were in one and three males and one female in the other (Morman 1979). In a trib- utary of southern Lake Superior, Purvis (1970) noted that 97% of the metamorphosed specimens collected in August were males and in June, 75% of the spawn- ers were also males.
In a Michigan river, [chthyomyzon fossor was observed in seven nests on 13 June when water tem- peratures ranged from 16.5° to 20.5°C (daily mean
18°C) [Morman 1979]. Spawning occurred in a shal- low, pool-riffle, high-gradient stretch of the stream. Nests were inconspicuously located in interstices beneath large stones (18 to 36 cm in diameter) and were poorly defined. Spawners were unobtrusive as had been observed by Reighard and Cummins (1916).
The number of eggs laid is roughly in proportion to the size of the female. The actual fecundity of nine Ichthyomyzon fossor females from Quebec (128 to 150 mm TL) averaged 1524 eggs (range 1115 to 1979 eggs) (Vladykov 1951) whose average diame- ter was 1.01 mm. Leach (1940) recorded 780 eggs in a 92 mm TL ripe female. The eggs are demersal (Fuiman 1982) and seem to develop in an extremely adhesive glue-like mass under artificial conditions (Leach 1940) where the incubation period lasted 9 days at 18°C (Smith et al. 1968).
After fertilization, the eggs become covered by the substrate in and around the nests (Hardisty and Potter 1971). After hatching, the proammocoetes emerge from the substrate and drift downstream where they burrow into silt beds, especially along protected banks (Piavis 1971).
Behavior/Adaptability
The young larvae settle down into the soft bottom of slowly flowing waters where they are carried by the current. According to Sawyer (1959), the mouth is directed towards the current, with the upper sec- tion of the burrow sloping obliquely towards the mud surface. For several years, they lie concealed in the silt deposits, feeding on desmids, diatoms and protozoans (Scott and Crossman 1973) strained from the water. Since their burrows at the substrate sur-
1992
face are sometimes closed off, food may be drawn from the sediments, depending on environmental conditions and activity of the ammocoetes (Moore and Mallatt 1980). In fact, detritus is frequently reported in the gut contents of all species of lam- preys, although its relative abundance may vary with season and locality (Hardisty and Potter 1971).
Species Movement
It appears that ammocoete movement differs between streams owing probably to variations in such conditions as flow and bottom stability, current velocity, flooding and ammocoete density in relation to preferred habitat (Morman et al. 1980). Hardisty and Potter (1971) suggested that in some streams, particularly those with low gradients, stable flows and suitable habitats, the downstream migration of lamprey larvae is minimal. It appeared to Leach (1940) that ammocoetes moved only when the sub- strate was disturbed or when food was in short sup- ply. Downstream migration takes place primarily at night; thus, predation by diurnal birds and mammals is minimal.
Limiting Factors
Lowering of water levels is probably a significant ammocoete mortality factor (Scott and Crossman 1973). Such is the case in the Yamaska River, where severe low water levels are regularly recorded in summer; these are generally followed by degradation of the aquatic environment (Mongeau et al. 1988). Siltation and pollution are a threat to successful spawning which requires a suitable substrate of clear gravel (Bailey 1959; Starrett et al. 1960). General deterioration in river habitat may reduce the avail- able food supply of larvae and increasing levels of toxic chemicals may cause direct mortality.
Richards (1976) demonstrated a reduction in num- bers of Ichthyomyzon fossor larvae and other warm- water fishes in a Michigan basin concurrent with the trend toward an increase in the relative abundance of coldwater species between the 1920s and 1972; he hypothesized that these changes were caused by a decrease in average water temperatures after that particular Michigan river basin was reforested and low-head impoundments were removed.
It is assumed that larval lampreys are largely immune from predation because of their burrowing sedentary habits (Churchill 1947; Hardisty and Potter 1971). However, evidence that ammocoetes are readily eaten by predatory fish is found in their formerly common and widespread use as bait (Vladykov 1949; Scott and Crossman 1973). In the course of field work carried out in the Ottawa River at Ottawa in the spring of 1979 and 1980, I observed unidentified predatory fishes capture ammocoetes swimming at the surface away from the electrical field generated by an electroshocker.
LANTEIGNE: STATUS OF THE NORTHERN BROOK LAMPREY 11
Lampreys on nests are probably most vulnerable to predators because they are more exposed in rela- tively shallow water and are not cautious. Therefore, in streams with few spawners, predators could reduce or prevent successful spawning (Morman et al. 1979).
Starting in 1958, Sea Lamprey (Petromyzon mari- nus) control programs in the upper three Great Lakes — Huron, Michigan and Superior — were carried out in Canadian and American streams with the help of a non-selective lampricide (Smith and Tibbles 1980). These programs were extended to Lake Ontario in 1971. In the process, native lampreys were inadver- tently destroyed and their distribution throughout the Great Lakes watershed was greatly reduced. For example, 64% of the Lake Superior streams inhabit- ed by native lampreys required treatment (Schuldt and Goold 1980). Lampricide was thus applied to 81 of the 105 streams inhabited by chthyomyzon larvae and the genus subsequently disappeared from 41 of the treated streams. They were readily eliminated from watersheds where they were confined to short stretches and where few sources of recruitment were available. Native lampreys disappeared from most streams unless they inhabited areas above barriers, in lentic environments, in tributaries in which Sea Lamprey did not spawn, or in difficult to treat areas such as oxbows, beaver ponds, long estuaries and springs. These changes reflect, in general, the results in the other Great Lakes where Sea Lamprey control programs were carried out.
Fecundity of a species is important in its recovery after lampricide treatment. In [chthyomyzon fossor, fecundity was found to be twelve times less than its parasitic stem species, [chthyomyzon unicuspis (Vladykov 1951). Its low fertility and mobility due to its non-parasitic nature suggest that it would be more vulnerable to chemical treatment than would parasitic lampreys.
Special Significance of the Species
All species, lampreys included, are part of our bio- diversity heritage. While some may feel that all lam- preys should be eradicated, it must be remembered that they are one of the oldest and most successful groups of living fishes (Beamish 1987). As such, they offer an excellent opportunity to study evolu- tion in fishes and the reasons for their continued suc- cess in a changing environment. Even though the Northern Brook Lamprey has scientific interest, it is doubtful that the general public would support its protection.
Concern over the loss of non-parasitic lampreys was expressed by Vladykov (1973). According to him, a large concentration of ammocoetes in a brook is very favorable to its ecosystem. As prey of the Rainbow Trout (Oncorhynchus mykiss), Smallmouth Bass (Micropterus dolomieui), Grass Pickerel (Esox
i THE CANADIAN FIELD-NATURALIST
americanus) [Vladykov 1949], American Eel (Anguilla rostrata) [Perlmutter 1951], Northern Pike (Esox lucius) [McPhail and Lindsey 1970] and Rock Bass (Ambloplites rupestris) [Hubbs and Trautman 1937], they represent an important link in the food chain. They also function as filter feeders and detriti- vores and so play a role in recycling dead organic matter into living tissue (Vladykov 1973).
Evaluation
Due to its restricted distribution in Canada, and eradication from some sites by the Sea Lamprey con- trol program, the Northern Brook Lamprey can be considered a vulnerable species according to COSEWIC definitions. Its occurrence as disjunct populations and its affinity for areas of poor natural drainage and warmwater habitats suggest that this species may have been more abundant and widespread in an earlier period (Morman 1979).
Acknowledgments
Financial support for this report was provided through World Wildlife Fund Canada and the Department of Fisheries and Oceans Canada. Thanks are extended to the Royal Ontario Museum and the Canadian Museum of Nature for the provision of collection records. I also wish to acknowledge D. E. McAllister of the Canadian Museum of Nature for his helpful comments and review of the manuscript.
Literature Cited
Anderson, A. A., and A. M. White. 1988. Habitat selec- tion of [chthyomyzon fossor and Lampetra appendix in a north-eastern Ohio stream. Ohio Journal of Science 88(2): 7.
Bailey, R. M. 1959. Parasitic lampreys (Ichthyomyzon) from the Missouri River, Missouri and South Dakota. Copeia 1959(2): 162-163.
Beamish, R. J. 1987. Status of the lake lamprey, Lampetra macrostoma, in Canada. Canadian Field- Naturalist 101(2): 186-189.
Churchill, W. S. 1947. The brook lamprey in the Brule River. Transactions of the Wisconsin Academy of Sciences, Arts and Letters 37(1945): 337-346.
Crossman, E. J., and H. D. van Meter. 1979. Annotated list of the fishes of the Lake Ontario watershed. Great Lakes Fisheries Commission Technical Reports 36.
Fuiman, L. E. 1982. Family Petromyzontidae, Pages
23-37 in Identification of larval fishes of the Great ©
Lakes basin with emphasis on the Lake Michigan drainage. Edited by N. A. Auer. Great Lakes Fisheries Commission Special Publication 82-3.
Hardisty, M. W., and I. C. Potter. 1971. The behaviour, ecology and growth of larval lampreys and the general biology of adult lampreys. Pages 85-125 in The biology of lampreys, Volume 1. Academic Press, London.
Hubbs, C. L., and M. B. Trautman. 1937. A revision of the lamprey genus Ichthyomyzon. Miscellaneous Publications of the Museum of Zoology, University of Michigan 35.
Vol. 106
Jyrkkanen, J., and D. G. Wright. 1979. First record of the Northern Brook Lamprey, Ichthyomyzon fossor, in the Nelson River drainage, Manitoba. Canadian Field- Naturalist 93(2): 199-200.
Lanteigne, J. 1981. The taxonomy and distribution of the North American lamprey genus Ichthyomyzon. M.Sc. thesis, University of Ottawa, 150 pages.
Leach, W. J. 1940. Occurrence and life history of the Northern Brook Lamprey, I[chthyomyzon fossor, in Indiana. Copeia 1940(1): 21-34.
McPhail, J. D., and C. C. Lindsey. 1970. Freshwater fishes of northwestern Canada and Alaska. Fisheries Research Board of Canada Bulletin 173.
Mongeau, J.-R., P. Dumont, L. Cloutier, et A.-M. Clément. 1988. Le statut du suceur cuivré, Moxostoma carinatum, au Canada. Canadian Field-Naturalist 102(1): 132-139.
Moore, J. W., and J. M. Mallatt. 1980. Feeding of larval lamprey. Canadian Journal of Fisheries and Aquatic Sciences 37(11): 1658-1664.
Morman, R. H., D. W. Cuddy, and P. C. Rugen. 1980. Factors influencing the distribution of sea lamprey (Petromyzon marinus) in the Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences 37(11): 1811-1826.
Morman, R. H. 1979. Distribution and ecology of lam- preys in the lower peninsula of Michigan, 1957-1975. Great Lakes Fisheries Commission Technical Reports 33.
Perlmutter, A. 1951. An aquarium experiment on the American eel as a predator on larval lampreys. Copeia 1951(2): 173-174.
Piavis, W. G. 1971. Embryology. Pages 361-400 in The biology of lampreys. Edited by M. W. Hardisty and I. C. Potter. Academic Press, London.
Pflieger, W. L. 1971. A distributional study of Missouri fishes. Publications of the Museum of Natural History, University of Kansas 20(3): 225-570.
Purvis, H. A. 1970. Growth, age at metamorphosis, and sex ratio of Northern Brook Lamprey in a tributary of southern Lake Superior. Copeia 1970(2): 326-332.
Reighard, J., and H. Cummins. 1916. Description of a new species of lamprey of the genus [chthyomyzon. Occasional Papers of the Museum of Zoology, University of Michigan 31: 1-12.
Sawyer, H. W. 1959. Burrowing activities of the larval lampreys. Copeia 1959(3): 256-257.
Scott, W. B., and E. J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada Bulletin 184.
Schuldt, R. J., and R. Goold. 1980. Changes in the distri- bution of native lampreys in Lake Superior tributaries in response to sea lamprey (Petromyzon marinus) control, 1953-77. Canadian Journal of Fisheries and Aquatic Sciences 37(11): 1872-1885.
Smith, B. R., and J. J. Tibbles. 1980. Sea lamprey (Petromyzon marinus) in Lakes Huron, Michigan and Superior: history of invasion and control, 1936-78. Canadian Journal of Fisheries and Aquatic Sciences 37(11): 1780-1801.
Smith, A. J., J. H. Howell, and G. W. Piavis. 1968. Comparative embryology of five species of lam-
1992 LANTEIGNE: STATUS OF THE NORTHERN BROOK LAMPREY 13
preys of the Upper Great Lakes. Copeia 1968(3): Viadykov, V. D. 1973. North American non-parasitic
461-469. lampreys of the family Petromyzontidae must be protect- Starrett, W. C., W. J. Harth, and P. W. Smith. ed. Canadian Field-Naturalist 87: 235-239.
1960. Parasitic lampreys of the genus Ichthyomyzon in Williams, J. E., J. E. Johnson, D. A. Hendrickson, S.
the rivers of Illinois. Copeia 1960(4): 337-346. Contreras-Balderas, J. D. Williams, M. Navarro- Vladykov, V. D. 1949. Quebec lampreys. List of species Mendoza, D. E. McAllister, and J. E. Deacon.
and their economical importance. Quebec Department of 1989. Fishes of North America endangered, threatened
Fisheries 26: 1—67. or of special concern: 1989. Bulletin of the American Viadykov, V. D. 1951. Fecundity of Quebec lampreys. Fisheries Society 14(6): 2—20.
Canadian Fish Culturist 10: 1-14.
Vladykov, V. D. 1952. Distribution des lamproies Accepted 31 May 1991 (Petromyzonidae) dans la province de Québec. Naturaliste canadien 79: 85-120.
Status of the Chestnut Lamprey, [chthyomyzon castaneus, in Canada*
J. LANTEIGNE 58-2069 Jasmine Crescent, Gloucester, Ontario K1J 7W2
Lanteigne, J. 1992. Status of the Chestnut Lamprey, [chthyomyzon castaneus, in Canada. Canadian Field-Naturalist 106(2): 14-18.
The Chestnut Lamprey, /chthyomyzon castaneus, is rare in Canada judging by the low number of collection records. It is found in the Qu’Appelle River Basin of Saskatchewan and the Red River Basin of Manitoba. These represent the northern limits of the range of this species in North America. It has never been the object of a directed survey in Canada; its precise status is thus unknown. The Chestnut Lamprey is not specifically protected in Canada except for the general protection granted through the fish habitat protection and pollution prevention sections of the Fisheries Act. The paucity of Canadian records supports a status of vulnerable for this species.
La lamproie brune, [chthyomyzon castaneus, est rare au Canada si l’on en juge par le faible nombre d’individus capturés. Elle est présente dans le bassin de la riviére Qu’Appelle, en Saskatchewan, et dans le bassin de la riviére Rouge, au Manitoba. Ces coordonnées représentent les limites septentrionales de l’aire de répatition de l’espéce en Amérique du Nord. Comme elle n’a jamais fait l’objet d’un relevé au Canada, sa situation précise y est inconnue. Elle n’est pas protégée dans les eaux canadiennes, sauf pour la protection générale que lui conférent les articles sur la protection de l’habitat des poissons et de la prévention de la pollution de la Loi sur les péches. Sa rare capture dans les eaux canadiennes indique que Vespeécee est vulnérable.
Key Words: Petromyzontidae, lampreys, Chestnut Lamprey, lamproie brune, Jchthyomyzon castaneus, vulnerable fishes.
The Chestnut Lamprey, [chthyomyzon castaneus, dark grey to olive (Cross 1967) and becomes blue- is a parasitic lamprey endemic to North America black after spawning, prior to death (Hubbs and where it is restricted to tributaries of the Gulf of Trautman 1937). The lateral line organs are darkly Mexico, the Gulf of St. Lawrence and Hudson Bay pigmented, especially the ventral ones which (Lanteigne 1981). The six species which comprise become intensely black with maturity (Hubbs and the genus, probably the most primitive among the Trautman 1937).
Northern Hemisphere lampreys (Hubbs and
Trautman 1937), can be grouped into three species Distribution
pairs each composed of a parasitic stem species and In the drainage basins of the Eastern United States a non-parasitic satellite species. After metamorpho- (Figure 2) the Chestnut Lamprey is found in the sis, the parasitic species feed mainly on teleost fishes | Hudson Bay drainage of North Dakota and Min- for one or more years (Scott and Crossman 1973) nesota; in the Western Great Lakes basin, only in while the non-parasitic species spawn soon after tributaries of Lake Michigan and Lake Huron of transformation. All lampreys die soon after spawn- Wisconsin, Michigan and Indiana; in the Upper
ing, be they parasitic or not. Missouri, in Nebraska and Kansas; in the Lower Missouri, in Missouri; in the Upper Mississippi, in Description Wisconsin, Iowa, Illinois and Missouri; in the Lower
The adult Chestnut Lamprey can reach a total Mississippi, in Illinois, Missouri and Mississippi; in length of 325 mm (ROM 28500); Hubbs and _ the Eastern Gulf, in Mississippi and Alabama; in the Trautman (1937) indicate a range of 105 to 310 mm Western Gulf, in Texas; in the Lower Arkansas-Red- (average 216 mm) while Lanteigne (1981) found a White, in Kansas, Missouri, Oklahoma, Texas, range of 89 to 261 mm. The number of trunk Arkansas and Louisiana; in the Tennessee- myomeres usually varies from 51 to 54 but can range Cumberland, in Kentucky, Tennessee and Alabama; from 49 to 56 (Hubbs and Trautman 1937). The disc © and in the Ohio, in Illinois and Indiana (Lanteigne is armed with strong, slender, sharp curved teeth of 1981) [Figure 3]. which the bicuspid endolaterals [usually 5 to 8, most In Canada, the Chestnut Lamprey is present in the frequently 5 (Lanteigne 1981)] represent the diag- Hudson Bay drainage of Saskatchewan and nostic character of the species (Figure 1). Its body is | Manitoba (Figure 4). In the Qu’Appelle River basin
*Report accepted by COSEWIC and Vulnerable Status assigned 9 April 1991.
14
1992
FIGURE 1. Ichthymomyzon castaneus: female, 224 mm TL; Black Lake, Ottawa, Co., Michigan, 1 March 1929; J. Metzelaar; UMMZ 101722. Note characteristic bicuspid endolateral teeth, in this case numbering 8.
of Saskatchewan, it has been captured in the Whitesand River (51°34'N, 101°56'W), in Round Lake (50°32'N, 101°22'W), in the Qu’Appelle River at Tantallon (50°32'N, 101°50W) [Royal Ontario Museum (ROM 34319)], and in the Shell River near Shellmouth (50°56'N, 101°29'W), Manitoba (Atton and Merkowsky 1983). In the Red River basin of Manitoba, it has been reported in the Rat River, 9.6 km upstream from St. Malo (49°16'N, 96°51 W) [Case 1970], in the Red River (Keleher 1952), between Selkirk and St. Andrews locks (50°09'N, 96°52'W) and at Winnipeg (49°53'N, 97°09'W [ROM 19839]; in Lake Winnipeg, near Black Island (51°12'N, 96°36'W) [ROM 16295] and Dog Head Point (51°45'N, 96°48'W) [ROM 285]; in the Assiniboine River (49°53'N, 97°08'W) [ROM 14341] where it was first reported in Canada at Portage la Prairie (49°59'N, 98°18'W) [Scott and Crossman 1973]; in the Winnipeg River (50°38'N, 96°19'W) [Hinks 1943]; and in Devil Creek at Red River (50°19'N, 96°49'W) [Manitoba Museum of
LANTEIGNE: STATUS OF THE CHESTNUT LAMPREY 15
Man and Nature (MMMN 1.5-356)]. This distribu- tion represents the northern limits of the range of this species in North America.
Protection
The Chestnut Lamprey is not listed as endangered, threatened or of special concern in North America (Williams et al. 1989). In Canada, the species is not the object of any legal protection other than the gen- eral protection granted under sections 34 to 42 of the Fisheries Act, which pertain to the protection of, and prevention of pollution in, fish habitats. In Manitoba, protection can be offered through the provincial Endangered Species Act by regulation.
Population Sizes and Trends
The Chestnut Lamprey was first reported in Canada by E. S. Thompson in 1898: he recorded the species as present in the Assiniboine River, at Portage la Prairie (49°59'N, 98°18'W) [Scott and Crossman 1973]. Subsequent collections in the Assiniboine River were not made until 1933 (ROM 14341). Since then, its capture in Canadian waters has been incidental but then the species has never been the object of a directed survey as it has no com- mercial significance. But, like other species, it has been taken in the course of museum and fisheries
Ficure 2. Principal drainage basins of Eastern United States where the genus Jchthyomyzon is found.
16 THE CANADIAN FIELD-NATURALIST
FIGURE 3. Distributional records of Ichthyomyzon casta- neus in Eastern United States.
surveys. It has never been captured in great numbers. However, Case (1970) observed a spawning group of about 50 spawning adults in the Rat River, which flows into the Red River in Manitoba.
No population estimates are available. There is no indication that the species is in danger of extinc- tion but the state of our knowledge is such that no predictions can be made. The better fish sampling methods used in the last two or three decades may be in part responsible for the greater number of lampreys appearing in fish collections. This increase should therefore not be viewed as a real increase in abundance. On the other hand, tillage of the soil in Western Canada and reduction of native year-round prairie grass and aspenland ground
cover has lead to the loss of 37 to 48% of the soil —
organic content and greatly increased soil erosion (Bird and Rapport 1986) This can be expected to have destroyed some gravel spawning ground and increased mortality of some species through silta- tion. Periphyton growth may also impact spawning beds through eutrophication from runoff of farm fertilizers. Increased use of pesticides and herbi- cides in grain farming may have had a negative direct impact on these lampreys or reduced popula- tions of some of their prey species.
Vol. 106
Habitat
Adult Chestnut Lampreys appear to inhabit the main course of moderate-sized rivers (Scott and Crossman 1973) and large creeks (Hubbs and Trautman 1937). It spawns in rivers from early to mid-June but possibly as late as early July; the peak of activity is in mid-June (Hubbs and Trautman 1937). In the Rat River, Manitoba, it spawned in areas of coarse gravel at a depth of 38 cm, a water temperature of 16.5°C and a current velocity of about 1 m/sec (Case 1970). The ammocoetes prefer areas of moderate current (about 0.3 to 0.7 m/sec), stable bottom of sand and silt with light growth of Chara. Larger ammocoetes found in quiet backwater areas of black muck and silt were only in areas where rooted vegetation was dense (Hall 1960).
General Biology Reproductive Capability
Like all lampreys, the Chestnut Lamprey breeds only once. The species is between 7 and 9 years old when it spawns, since it is presumed that the ammo- coete period lasts from 5 to 7 years. Metamorphosis of ammocoetes begins in August and is completed the following January. Active parasitic feeding begins that spring, with the greatest feeding activity in July. The adults are inactive over the next winter when their gonads start to mature (Scott and Crossman 1973). They mate, spawn and die soon after egg-laying is completed in June or July. The peak of sexual activity is in mid-June when water temperature varies from 16° to 22°C (Morman 1979). Ichthyomyzon castaneus seems to be a com- munal spawner; Case (1970) observed about 50 indi- viduals occupying a single nest in the Rat River, a tributary of the Red River in Manitoba. Spawners were observed excavating areas of coarse gravel riverbed at a water depth of about 38 cm where the river was 9.5 m across. The male would attach to the head of the female and coil its tail around the anteri- or part of her body. Up to five lampreys were observed attached to each other. Hall (1963) also reported spawning Chestnut Lampreys in a nest well hidden beneath a log. A 284 mm female Chestnut Lamprey captured in Oklahoma contained 42 000 eggs (Hall and Moore 1954). They are elliptical (0.64 mm by 0.56 mm), demersal and non-adhesive (Fuiman 1982). Under experimental conditions, the incubation period lasted 9 days at 18°C (Smith et al. 1968). In the Rat River, many small fishes, chiefly the Common Shiner (Notropis cornutus), were pre- sent immediately downstream of the nest, probably feeding on the eggs.
Behavior/Adaptability
The young larvae settle down into the soft bottom of slowly flowing waters where they are carried by the current. According to Sawyer (1959), the mouth is directed towards the current, with the upper sec-
92
LANTEIGNE: STATUS OF THE CHESTNUT LAMPREY 117/
FiGcure 4. Distributional records of [chthyomyzon castaneus in Canada.
tion of the burrow sloping obliquely towards the mud surface. For several years, they lie concealed in the silt deposits, feeding on desmids, diatoms and protozoans (Scott and Crossman 1973) strained from the water. Since their burrows at the substrate sur- face are sometimes closed off, food may be drawn from the sediments, depending on environmental conditions and activity of the ammocoetes (Moore and Mallatt 1980). In fact, detritus is frequently reported in the gut contents of all species of lam- preys, although its relative abundance may vary with season and locality (Hardisty and Potter 1971).
The parasitic adult attacks a wide variety of stream fishes and, like other parasitic lampreys, rasps into the flesh, consuming body fluids and mus- cles (Scott and Crossman 1973). In Oklahoma, where castaneus is the only parasitic lamprey species, Hall and Moore (1954) have found attached lampreys or their scars on the following host species: Shorthead Redhorse (Moxostoma macrolepidotum), Golden Redhorse (Moxostoma erythrurum), River Redhorse (Moxostoma carinatum), Smallmouth Buffalo ([ctiobus bubalus), Common Carp (Cyprinus carpio), Green Sunfish (Lepomis cyanellus), Largemouth Bass (Micropterus salmonoides) and Smallmouth Bass (Micropterus dolomieui). Hall (1960) observed Chestnut Lampreys attached to a number of stream fishes, including Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), Rainbow Trout (Oncorhynchus mykiss), White Sucker (Catostomus commersoni) and Burbot (Lota lota).
Species Movement No data are available on the migrations of the Chestnut Lamprey. All observers of lamprey migra-
tions nevertheless agree that lampreys are only active during the hours of darkness and that in the daytime they avoid the light, seeking out resting places under rocks or the cover of river banks (Hardisty and Potter 1971). Parasitic lamprey species migrate upstream from feeding areas in lakes and major rivers to spawn in tributaries close to areas where the larvae spend their hidden life (Larsen 1980).
Limiting Factors
The limiting factors are unknown in general, but suitable lamprey spawning and larval habitats seem to be disappearing because of siltation and pollution (Bailey 1959; Starrett et al. 1960). General deteriora- tion in river habitat may reduce available food sup- ply of larvae and adults. Increasing levels of toxic chemicals may cause direct mortality. River eutroph- ication may subject larvae to low winter oxygen lev- els and increase mortality due to lack of oxygen or increase predation if they leave their burrow (D.E. McAllister, Canadian Museum of Nature; personal communication).
Special Significance of the Species
All species, lampreys included, are part of our bio- diversity heritage. Parasitic species, like the parasitic adult Chestnut Lamprey, play a role in moderating populations of their prey. The larvae function as fil- ter feeders and detritivores and so play a role in recy- cling dead organic matter into living tissue (Vladykov 1973). While some may feel that all para- sitic lampreys should be eradicated, it must be remembered that lampreys are one of the oldest and most successful groups of living fishes (Beamish
18 THE CANADIAN FIELD-NATURALIST
1987). As such, they offer an excellent opportunity to study evolution in fishes and the reasons for their continued success in a changing environment. Even though the Chestnut Lamprey has scientific interest, it is doubtful that the general public would support its protection.
Evaluation
Due to its restricted distribution in Canada, the Chestnut Lamprey can be considered a vulnerable species according to COSEWIC definitions. It is not known to be abundant where it occurs in Canada and therefore its parasitism of economically important species is probably negligible in Canadian waters.
Acknowledgments
Financial support for this report was provided through World Wildlife Fund Canada and the Department of Fisheries and Oceans Canada. Thanks are extended to the Royal Ontario Museum and the Canadian Museum of Nature for the provision of collection records. I wish also to acknowledge D. E. McAllister and C. B. Renaud, of the Canadian Museum of Nature, and Karen Lloyd, of the Canadian Wildlife Service, for their helpful com- ments and review of the manuscript.
Literature Cited
Atton, F. M., and J. J. Merkowsky. 1983. Atlas of Saskatchewan fish. Saskatchewan Department of Parks and Natural Resources Technical Reports 83-2.
Bailey, R. M. 1959. Parasitic lampreys (Ichthyomyzon) from the Missouri River, Missouri and South Dakota. Copeia 1959(2): 162-163.
Beamish, R. J. 1987. Status of the Lake Lamprey, Lampetra macrostoma, in Canada. Canadian Field- Naturalist 101(2): 186-189.
Bird, D. M., and D. G. Rapport. 1986. State of the Environment Report for Canada. Environment Canada, Ottawa, Ontario.
Case, B. 1970. Spawning behavior of the Chestnut Lamprey, /chthyomyzon castaneus. Journal of the Fisheries Research Board of Canada 27(10): 1872-1874.
Cross, F. B. 1967. Handbook of fishes of Kansas. University of Kansas Museum of Natural History Miscellaneous Publications 45.
Fuiman, L. E. 1982. Family Petromyzontidae. Pages 23-37 in Identification of larval fishes of the Great Lakes basin with emphasis on the Lake Michigan drainage. Edited by N. A. Auer. Great Lakes Fisheries Commission Special Publication 82-3.
Hall, J. D. 1960. Preliminary studies on the biology of native Michigan lampreys. M.Sc. thesis, University of Michigan, Ann Arbor, Michigan. 39 pages.
Vol. 106
Hall, J. D. 1963. An ecological study of the chestnut lam- prey, Ichthyomyzon castaneus Girard, in the Manistee River, Michigan. Ph.D. thesis, University of Michigan, Ann Arbor, Michigan. 101 pages.
Hall, G. E., and G. A. Moore. 1954. Oklahoma lampreys: their characterization and distribution. Copeia 1954 (2): 127-135.
Hardisty, M. W., and I. C. Potter 1971. The behaviour, ecology and growth of larval lampreys and The general biology of adult lampreys. Pages 127-236 in The Biology of Lampreys. Volume 1. Academic Press, London.
Hinks, D. 1943. The fishes of Manitoba. Manitoba Department of Mines and Natural Resources, Winnipeg, Manitoba.
Hubbs, C. L., and M. B. Trautman. 1937. A revision of the lamprey genus [chthyomyzon. Miscellaneous Publications of the Museum of Zoology, University of Michigan 35.
Keleher, J. J. 1952. Notes on fishes collected from Lake Winnipeg region. Canadian Field-Naturalist 66(6): 170-173.
Lanteigne, J. 1981. The taxonomy and distribution of the North American lamprey genus [chthyomyzon. M.Sc. thesis, University of Ottawa, Ottawa, Ontario. 150 pages.
Larsen, L. O. 1980. Physiology of adult lampreys, with special regard to natural starvation, reproduction and death after spawning. Canadian Journal of Fisheries and Aquatic Sciences 37(11): 1762-1779.
Moore, J. W., and J. M. Mallatt. 1980. Feeding of larval lamprey. Canadian Journal of Fisheries and Aquatic Sciences 37(11): 1658-1664.
Morman, R. H. 1979. Distribution and ecology of lam- preys in the lower peninsula of Michigan, 1957-1975. Great Lakes Fisheries Commission Technical Reports 33.
Sawyer, H. W. 1959. Burrowing activities of the larval lampreys. Copeia 1959(3): 256-257.
Scott, W. B., and E. J. Crossman. 1973. Freshwater Fishes of Canada. Fisheries Research Board of Canada Bulletin 184.
Smith, A. J., J. H. Howell, and G. W. Piavis. 1968. Comparative embryology of five.species of lampreys of the Upper Great Lakes. Copeia 1968(3): 461-469.
Starrett, W. C., W. J. Harth, and P. W. Smith. 1960. Parasitic lampreys of the genus [chthyomyzon in the rivers of Illinois. Copeia 1960(4): 337-346.
Vladykov, V. D. 1973. North American nonparasitic lam- preys of the family Petromyzonidae must be protected. Canadian Field-Naturalist 87: 235-239.
Williams, J. E., J. E. Johnson, D. A. Hendrickson, S. Contreras-Balderas, J. D. Williams, M. Navarro- Mendoza, D. E. McAllister, and J. E. Deacon. 1989. Fishes of North America endangered, threatened, or of special concern. 1989. Fisheries 14(6): 2-20.
Accepted 31 May 1991
Status of the Y-Prickleback, Allolumpenus hypochromus, in Canada*
R. E. CAMPBELL 2880 Carling Avenue, #1410, Ottawa, Ontario K2B 7Z1
Campbell, R. E. 1992. Status of the Y-Prickleback, Allolumpenus hypochromus, in Canada. Canadian Field-Naturalist 106(1): 19-23.
The Y-Prickleback, Allolumpenus hypochromus, is a small stichaeid known only from the southwest coastal waters of British Columbia. Although literature records extend the range to southern California, reports from U.S. waters are not confirmed. Information on its biology and ecology is extremely limited, but it appears to be a rare species with a narrow distribution limited by its habitat requirements. Despite its apparent rarity, viable populations exist and the status of the species appears to be secure for the present.
La lompénie i-grec, Allolumpenus hypochromus, est un petit stichéide connu seulement des eaux cdtiéres du sud-ouest de la Colombie-Britannique. Bien que la littérature scientifique rapport sa présence jusqu’au sud de la Californie, les mentions de cette espéce dans les eaux des Etats-unis ne sont pas corroborées. Les données sur la biologie et l’écologie de cette éspéce sont trés limitées, mais l’espéce est apparemment rare avec une répartition restreinte limitée par ses besoins d’habi- tat. Néanmoins, des populations viables existent, et le statut de cette espéce semble étre stable 4 ce moment-ci.
Key Words: Stichaeidae, pricklebacks, Opisthocentrinae, Y-Prickleback, lompénie i-grec, Allolumpenus hypochromus, Y-
Blenny, marine fishes.
The Y-Prickleback, Allolumpenus hypochromus Hubbs and Schultz 1932, is a small marine fish known from a very few specimens recorded off the coast of British Columbia. The species was first described in 1932 (Hubbs and Schultz 1932) but there have been few reported sightings since (see Table 1).
It is difficult enough to ascertain the status of a species confined in lakes or streams, but it is even more difficult to evaluate the status of poorly known species in the immensity of the ocean. If collection records or surveys indicate that a species is rare, is this simply an artifact of sampling methods and effort? Some species believed to be rare have been found to be locally common when directed surveys were undertaken using appropriate gear in the true habitat (McAllister et al. 1985). Current status, how- ever, must be evaluated in terms of known speci- mens and degree of sampling.
Description
The Stichaeidae are a fairly large family (37 gen- era, with about 74 species) of circumboreal, bottom dwelling, marine fishes (Hart 1973; Nelson 1984; McAllister 1990). Pricklebacks have elongated, compressed or cylindrical bodies with a long dorsal fin (entirely spinous in most species) extending the length of the body and sometimes confluent with the caudal fin. The anal fin is also long and may be con- fluent with the caudal fin. The pelvic fins, if present,
are reduced, and consist of one spine and three or four rays. The lateral line is usually not well devel- oped (though four lateral lines have been recorded) and the body is covered with small, circular overlap- ping scales. Eight species occur in the Canadian Atlantic, two in the Arctic, and some 14 in the Canadian Pacific (Hart 1973; Scott and Scott 1988; McAllister 1990).
The Y-Prickleback is a member of the subfamily Opisthocentrinae, characterized by pelvic fins with one spine and three soft rays, large pectoral fins, lat- eral line canal and pores indistinct or absent, and 53- 94 vertebrae (Makushov 1958). This species is the only representative of its genus. It is distinguished by the united gill membranes joined to the isthmus at the centre, the Y-shaped markings (Figure 1), spots at the base of the dorsal fin, the long pelvic fins with one spine and three soft rays, the dorsal fin with 49 spines, and the anal fin with one spine and 31 rays (Hubbs and Schultz 1932; Clemens and Wily 1961; Hart 1973).
The following general description is based on Hubbs and Schultz’s (1932) description of the holo- type. These are small fish measuring to 7.4 cm stan- dard length. The body is slender, moderately elon- gate and slightly compressed anteriorly and covered with small cycloid scales except for the head which is naked. The head is bluntly rounded; the mouth ter- minal and moderate in size, extending to a point below the middle of the large, oval eye. There are
*Report accepted by COSEWIC 9 April 1991, No Status Designation Required.
20 THE CANADIAN FIELD-NATURALIST Vol. 106
TABLE 1. Existing specimen records of Allolumpenus hypochromus. All are from British Columbian waters.
Source Location (latitude, longitude) Date
Hubbs and Newcastle Island, near Naniamo 8 August 1927
Schultz (1932) (Holotype) [see also UBC 72-152].
NMC 65-0043 Browning Entrance, Queen Charlotte Islands 17 June 1964 (53°40'00"N, 130°34'00"W)
UBC 65-0295 Baker Passage, Vancouver Island 27 June 1962 (50°01'00"N, 124°56'00"W)
UBC 65-096 Malcom Island 12 June 1963 (50°40'24’N, 127°11'00"W)
UBC 72-152 Newcastle Island =
(49°12'00"N, 123°56'00"W)
BCPM 984-421 (52°04'30"N, 132°00'24"W)
NMC:
1 July 1990). UBC: . University of British Columbia BCPM:
moderate-sized teeth on both jaws, but the vomerine and palatine bones are toothless. The lateral line canal and pores are absent. The caudal peduncle is compressed and both the anal and dorsal fins are free of the caudal. Makuskov (1958) pointed out that fishes without an obvious lateral line usually lack the canal and/or pores, but have the lateral line neuro- cysts — the essential lateral line.
The overall colour is brownish with a striking and distinctive irregular series of black markings on the sides of the body. Some of these form a distinct “Y” below the midline (Figure 1). There is also a series of five dark spots along the base of the dorsal fin (located between dorsal spines 11-12, 20-21, 29-30, 38-39, and 44-46), and dorsal and ventral black spots at the base of the caudal fin connected by a black bar (Hubbs and Schultz 1932; Clemens and Wily 1961; Hart 1973).
Distribution
The species has been reported to be endemic to Canada (McAllister et al. 1985) where it is known (from bon a fide records) only from Departure Bay, Baker Pass, Saanich Inlet, and Browning Entrance, British Columbia (Figure 2, Table 1). DeLacy et al. (1966) listed the species in their unpublished list of fishes of Puget Sound, but omitted it in an earlier unpublished checklist (DeLacy et al. 1963). It is not included in their subsequent published report (DeLacy et al. 1972). There is apparently no data to substantiate the earlier inclusion (A. E. Peden, British Columbia Provincial Museum, Victoria, British Columbia; personal communication).
Eschmeyer and Herald’s (1983) distribution for the species from southern British Columbia to
Tasu Sound, Queen Charlotte Islands
16 September 1984
National Museums of Canada (National Museum of Natural Sciences: renamed Canadian Museum of Nature,
British Columbia Provincial Museum (now Royal British Columbia Museum).
California may be in error as its presence in waters off California has not been confirmed (R. N. Lea, California Department of Fish and Game, California Fisheries Laboratory, Golden Beach, California; per- sonal communication). The Eschmeyer and Herald (1983) citation may have been based on Hubbs et al. (1979), which also lacked reference to collection data, or be based on the unpublished work of DeLacy et al. (1966). None are recorded at the University of Washington (T. Pietsch, University of Washington, Seattle, Washington; personal commu- nication).
There is no known reason for the species to be limited to Canadian waters; similar habitats may exist along the U.S. coast from Washington to north- ern California (W. N. Eschmeyer, California Academy of Sciences, San Francisco, California; R. N. Lea; personal communications). The species is poorly known because of its small size (it would not be caught, for example, in commercial fish or shrimp gear) and its existence in a habitat which does not make for easy collecting (Peden, personal communi- cation).
Protection
There is no specific legislation for the protection of the species. General protection , if required, could be provided under appropriate sections of the Fisheries Act.
Population Sizes and Trends
Detailed information on population sizes and trends for this species is lacking. It is documented only in Canada, and only from presence/absence data.
1992
CAMPBELL: STATUS OF THE Y-PRICKLEBACK Dal
FIGURE 1. Photograph of a freshly caught specimen (53 mm) of the Y-Prickleback, Allolumpenus hypochromus, (BCPM 984-421) taken in Tasu Sound, Fairfax Inlet, Queen Charlotte Islands 16 September 1984. Photograph courtesy A. E. Peden, British Columbia Provincial Museum. (Note anterior spines of the dorsal fin are depressed and should
be raised like the rest of the fin).
McAllister et al. (1985) suggested that the species should be considered rare (vulnerable) in Canada and protected as such. However, Peden (personal commu- nication) feels that the species is poorly known because of its small size and its habitat. Lea and Eshmeyer (personal communications) are of a similar opinion and suspect that the species range does extend south to California, but has simply gone unno- ticed. This may be, but given the distinctive markings of this species it is doubtful it would be missed, if present, in collections, or misidentified with other members of the family. General collection survey activity has been fairly vigorous along the Pacific coast (e.g., Peden and Gruchy 1971; Barraclough and Peden 1976), with several new species and range expansions of others being documented.
In addition to the few bon a fide Canadian records (Table 1), Peden (personal communication) observed several individuals on a trip to the Queen Charlotte Islands with the submersible “Pisces IV”. Barraclough and Fulton (1968) also reported the presence of larval Allolumpenus hypochromus indi- viduals in surface trawl tows in Saanich Inlet during June and July 1966, indicating the presence of a viable population in the area.
Habitat
The recorded specimens (Table 1) were captured at depths varying from about 30 to 100 m over rocky or sandy substrates. Peden (personal communication) observed several specimens from the “Pisces IV” on a very steep slope of detritus and broken shell on the side of a rock wall. The Canadian Museum of Nature
specimen came from a similar sand, coral and fine shell bottom. The location was sheltered from tide and wave flow. Barraclough and Fulton (1968) col- lected 13 mm larvae on the surface of Saanich Inlet, mid-channel, in June and July.
No other information concerning the habitat of the species is apparently available, but most species of this group prefer cool waters (close to 0°C) and high salinity (above 30%) and are benthophages (Andriashev 1954; Makushov 1958).
General Biology
The biology of the species has not been studied and very little is known concerning the biology of the other species and genera in the subfamily. No reproductive or growth data are available. Recorded fecundities for some members of the subfamily are low, usually less than 1000 eggs (Andriashev 1954).
Generally, the smaller stichaeids are said to be benthophagic, feeding on small polychaetes, mol- luscs and crustaceans (Andriashev 1954). Barraclough, and Fulton (1968) recorded that the lar- vae they collected appeared to have been feeding on copepods. This species has not been reported from the stomach contents of other fishes. Other members of the group have been reported as prey for larger fishes (Andriashev 1954; Scott and Scott 1988).
Limiting Factors
Not known! If the habitat is limited by water tem- perature as for most species in the family (Andriashev 1954), they may not be found much fur- ther south than has been documented.
22: THE CANADIAN FIELD-NATURALIST
Vol. 106
North A Pole T As
wa f Nee
Rea K } A
BN CRG neon ge { ogee ee
SS
Ean
f2))} sf)
MCR94
Ficure 2. Map of the world distribution of the Y-Prickleback, Allolumpenus hypochromus. The five locations shown are
documented in Table 1.
Special Significance of the Species
The Y-Prickleback is of no commercial interest and probably is not an important forage species. The lack of information and its peculiar markings lend an air of mystery to the species. It should be of scientif- ic relevance in determining the evolution of coastal and offshore marine habitats.
Evaluation
Based on bon a fide records it appears that the species is endemic to Canada and is a relatively rare member of the British Columbia coastal marine fauna. There are at present no known threats to the species or its habitat and, despite the perceived rari- ty, viable populations appear to exist. The future of the species would seem to be secure for the present.
However, all known specimens come from a very limited area where they are vulnerable to a single destructive event of only modest scale (e.g. ocean dumping of toxic materials).
Literature Cited
Andriashev, A. P. 1954. Ryby sevemykh morei SSSR. Akademiya Nauk Soyuza Sovetskikh sotsialisticheskikh Respublik, Moskoa — Leningrad: 244—275. [Fishes of the northern sea of the U.S.S.R. Translated from Russian. Israel Program for Scientific Translations, Jerusalem 1964.
Barraclough, W. E., and J. D. Fulton. 1968. Data record food of larval and juvenile fish caught with a surface trawl in Saanich Inlet during June and July 1966. Fisheries Research Board of Canada Manuscript Report Series Number 1003: 1-78.
992
Barraclough, W. E., and A. E. Peden. 1976. First records of the pricklebreast poacher (Stellerina xyosterna), and the cutfin poacher (Xeneretmus leiops) from British Columbia, with keys to the poachers (Agonidae) of the Province. Syesis 9: 19-23.
Clemens, W. A., and G. V. Wilby. 1961. Fishes of the Pacific coast of Canada. Fisheries Research Board of Canada Bulletin 68: 1-443.
DeLacy A. C., R. L. Dryfoos, and B. S. Miller. 1963. Preliminary checklist of the fishes of Puget Sound. [Unpublished Report]. Division of Marine Resources, University of Washington, Seattle, Washington.
DeLacy A. C., R. L. Dryfoos, and B. S. Miller. 1966. Preliminary checklist of the fishes of Puget Sound cor- rected to 1966. [Unpublished Report]. Division of Marine Resources, University of Washington, Seattle, Washington.
DeLacy A. C., R. L. Dryfoos, and B. S. Miller. 1972. Checklist of Puget Sound fishes. Washington Sea Grant Publications, Division of Marine Fisheries, University of Washington, Seattle, Washington. 43 pages.
Eschmeyer, W. N., and E. S. Herald. 1983. A field guide to Pacific coast fishes of North America. Houghton Mifflin, Boston, Massachusetts. 336 pages.
Hart, J. L. 1973. Pacific fishes of Canada. Fisheries Research Board of Canada Bulletin 180: 1-740.
Hubbs, C. L., and L. P. Schultz. 1932. A new blenny from British Columbia with records of two other fishes new to the region. Contributions to Canadian Biology and Fisheries 7(22): 319-324.
CAMPBELL: STATUS OF THE Y-PRICKLEBACK 8}
Hubbs, C. L., W. I. Follett, and L. J. Dempster. 1979. List of the fishes of California. Occasional Papers of the California Academy of Sciences Number 133: 1-51.
Lindberg, G. U., and Z. V. Krasyukova. 1975. [Fishes of the Sea of Japan and adjoining parts of the Okhotsk and Yellow Seas]. In Russian. Nauka Press, Leningrad, Part 4: 27-109.
Makuskov, V. M. 1958. The morphology and classifica- tion of the northern Blennioid fishes (Stichaeoidae, Blennioidei, Pisces). Proceedings of the Zoological Institute (Trudy Zoological Institute - Akademiya Nauk Soyuza Sovetskikh Satsialisticheskikh Respublik) 25: 3-129. [Translated from the Russian by the Ichthyological Library, U.S. National Museum 1959].
McAllister, D. E. 1990. List of the fishes of Canada. Syllogeus (64): 1-310.
McAllister, D. E., B. J. Parker, and P. M. McKee. 1985. Rare, endangered and extinct fishes in Canada. Syllogeus 54: 1-193.
Nelson, J. S. 1984. Fishes of the world. Second edition. John Wiley & Sons, Toronto, Ontario. 523 pages.
Peden, A. E., and C. G. Gruchy. 1971. First record of the blue-spotted poacher, Xeneretmus truacanthus, in British Columbia. Journal of the Fisheries Research Board of Canada 28: 1347-1348.
Scott, W. B., and M. G. Scott. 1988. Atlantic fishes of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences Number 219. 731 pages.
Accepted 31 May 1991.
Status of the Pixie Poacher, Occella impi, in Canada*
R. E. CAMPBELL
2880 Carling Avenue #1410, Ottawa, Ontario K2B 7Z1
Campbell, R. E. 1992. Status of the Pixie Poacher, Occella impi, in Canada. Canadian Field-Naturalist 106(1): 24-26.
The Pixie Poacher, Occella impi, was first recognized as a distinct species endemic to the Canada fauna little more than 20 years ago. The species was described from a single juvenile specimen collected in 1957 from the Queen Charlotte Islands of British Columbia. There is no other information regarding the species beyond that published with the description. This apparently rare species appears to be restricted to a habitat vulnerable to catastrophic events.
Il y aun peu pleu de vingt ans, en reconnaissait le lutin, Occella impi, comme une espece endémique a la faune canadienne. L’espésce put décrite a partir d’un seul spécimen juvénile collectionné en 1957 pres des Iles de la Reine Charlotte en Colombie-Britannique. De fait, il n’y en a pas d’autre information concernant cette espece sauf ce qui a été publiée avec la description. La répartition de cette espéce, manifeste comme rare, semble étre limitée a un habitat vulnérable a des événe-
ments catastrophiques.
Key Words: Poachers, Agonidae, Pixie Poacher, lutin, Occella impi, marine fishes, North Pacific, British Columbia.
Sea poachers (Agonidae) are members of a family of small, marine, bottom dwellers distinguished by the body covering of non-overlapping rows of adjoining bony plates in place of scales. These are fishes primarily of the North Pacific Ocean, although three species are known from the North Atlantic (Scott and Scott 1988), and another from the South Pacific (J. S. Nelson, Department of Zoology, University of Alberta, Edmonton, Alberta; personal communication).
The Pixie Poacher, Occella impi Gruchy 1970, was described from a single specimen from Graham Island, Queen Charlotte Islands, British Columbia in 1957. The species has not been reported since. Due to its apparent rarity, and occurrence in a habitat now susceptible to potentially catastrophic events such as oil spills, the status of this endemic species is of con- cern to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
Description
The Pixie Poacher is a small fish, the single indi- vidual described by Gruchy (1970) [Canadian Museum of Nature catalogue number 60-283] was presumed to be a juvenile and is 20.6 mm total length [TL] (Figure 1). Gruchy (1970) recognized the species as a poacher (Brachyospininae) rather than an alligatorfish. The Pixie Poacher is elongate with a long caudal peduncle and in place of scales the body is covered by rows of adjoining ridged or spinous plates. There is a small, flaplike barbel at the posterior end of the upper jaw (Gruchy 1970; Hart 1973). The species has two dorsal fins, a rounded caudal fin and long pectoral fins which stretch
beyond the origin of the first dorsal fin. The pelvic fins are small and inserted well forward on the tho- rax (Gruchy 1970).
The preserved specimen is brown in colour, the ventral surface being slightly lighter. The body lacks distinctive markings although the peduncle appears more heavily pigmented as does the base of the cau- dal fin. A brownish stripe is apparent on the upper third of the base of the pectoral fin (Gruchy 1970; Hart 1973).
Identifying features (relative to other agonids) include the deep head, pits along the lower jaw and suborbital ridge, the posterior position of the anus, pricklelike plates on the breast and the scarcity of dorsolateral plates (Hart 1973). Gruchy (1970) also mentions the presence of vomerine and palatine teeth as diagnostic.
Distribution
Known only from the single record from Graham Island (Figure 2), Queen Charlotte Islands, British Columbia (54°02'N, 132°00'W).
Protection
No specific legislation exists for the protection of the species. General protection is available, if required, through the Fisheries Act.
Population Sizes and Trends
No information on possible population sizes and trends is available. Hart (1973) speculated that, given the small size of the fish and its tidal pool habitat, it may be quite common. However, the spec- imen described (Gruchy 1970) was thought to be a
*Report accepted by COSEWIC 9 April 1991, Insufficient scientific information for status determination.
24
19
CAMPBELL: STATUS OF THE PIXIE POACHER 25
Imm —_—_——>
FIGURE 1. Holotype of Occella impi (NMC60-283) [drawing by C. Douglas, courtesy of D. E. McAllister,
Canadian Museum of Nature].
juvenile and the adults, if like other agonids (Andriashev 1954) would probably not be found in this habitat except during spawning. In addition, the species has not been reported in subsequent collec- tions since the record of the first specimen in 1957 despite repeated sampling for agonids in the area (Peden and Gruchy 1971; Miller and Lea 1972; Hart 1973; Barraclough and Peden 1976). This lack of further collections is particularly surprising as these surveys have confirmed the presence of other ago- nids known from the area. In addition, they have added new records for the Cutfin Poacher (Xeneretmus leiops) and the Pricklebreast Poacher (Stellerina xyosterna), previously known only from United States coastal waters to the south (Barraclough and Peden 1976). The previously known range of these species was extended by 280 and 850 km respectively.
Habitat
Habitat preferences of the Pixie Poacher are not known. The holotype was collected from a brackish tidal pool, between high and low tides, on a coarse sand pebble beach at the mouth of the Skonum River, McIntyre Bay, Graham Island, British Columbia (Bousfield 1962).
Adults of closely related species are most often encountered in coastal waters at depths of 18 to 90 m on sandy and muddy bottoms (Andriashev 1954; Hart 1973; Barraclough and Peden 1976), while juveniles and larvae are found in shallower inshore sandy habitats (Barraclough and Peden 1976).
Shrimp, juvenile crabs, sand dollars, small sole, and sculpins are often found in association with juvenile agonids in inshore collections (Barraclough and Peden 1976).
Biology
Not known. The poachers are, in general, a poorly studied group of fishes. Adults are thought to enter shallow bays and deltas to spawn in the spring (Andriashev 1954). The eggs are small, averaging 1.5 mm in diameter, and females lay less than 1000 eggs, probably 400 to 500 (Andriashev 1954).
The sex and age of the holotype have not been determined, but Gruchy (1970) assumed it to be a juvenile based on the location of capture and the length (20.6 mm TL). Juveniles of closely related species such as the Pricklebreast and Warty (Occella verrucosa) poachers are found in similar habitat and range from 15 to 37 and 28.5 to 42.0 mm TL respec- tively. Adults of these are considerably larger, up to 97 mm TL (Barraclough and Peden 1976).
Agonids swim using the pectoral fins and are thought to feed on copepods, euphasiids, and decapods (Andriashev 1954; Hart 1973). Larvae and juveniles are found inshore in sheltered bays and deltas (Andriashev 1954).
Limiting Factors
Not known. A catastrophic event such as a major oil spill has the potential for serious affects on juve- niles in inshore habitats.
Special Significance of the Species
With the exception of the Warty Poacher, this is the only species of the genus Occella known from Canada. Too small to be of commercial importance, they may serve as a forage fish for larger species. Agonids from the North Atlantic and the Arctic have been reported from the stomachs of cod, haddock and halibut, but bony plates may make them unattractive as prey (Scott and Scott 1988).
Occella impi is of particular interest in that it is known from a only single specimen. The species has been recognized by the American Fisheries Society [AFS] (Robins et al. 1980).
Evaluation
It would be logical to assume that the species should be considered rare and vulnerable. However, the family in general is poorly understood and there is some question as to the validity of the species (A. E. Peden, British Columbia Provincial Museum, Victoria, British Columbia; personal communica- tion). If it is a valid species, it is probably rare in Canadian waters. The species is not under any pre- sent threat, but eggs, larvae and juveniles would be susceptible to a major oil spill, such as that which
26 THE CANADIAN FIELD-NATURALIST
Vol. 105
FicurRE 2. Known distribution of Occella impi (single record from Graham Island, 54°02'N, 132°00'W).
recently occurred further north in Alaska. Tanker traffic off the British Columbia coast poses regular risk to all British Columbian shallow water marine fishes.
Literature Cited
Andriashey, A. P. 1954. Fishes of the northern seas of the U.S.S.R. Translated from the Russian. Israel Program for Scientific Translation, Jerusalem 1964. Number 836: 453-471.
Barraclough, W. E., and Alex E. Peden. 1976. First.
records of the pricklebreast poacher (Stellerina xyosterna), and the cutfin poacher (Xeneretmus leiops) from British Columbia, with keys to the poachers (Agonidae) of the Province. Syesis 9: 19-23.
Bousfield, E. L. 1962. Investigations on seashore inverte- brates of the Pacific Coast of Canada 1957 and 1959. I. Station List. National Museums of Canada Bulletin 1985: 72-89.
Gruchy, C. G. 1970. Occella impi, a new species of sea poacher from British Columbia with notes on related
species (Agonidae: Pisces). Journal of the Fisheries Research Board of Canada 27: 1109-1114.
Hart, J. L. 1973. Pacific fishes of Canada. Fisheries Research Board of Canada Bulletin 180: 1-740.
Miller, D. J., and R. N. Lea. 1972. Guide to the coastal marine fishes of California. California Department of Fish and Game, Fisheries Bulletin 157: 1-235.
Peden, A. E., and C. G. Gruchy. 1971. First record of the blue spotted poacher, Xeneretmus truacanthus, in British Columbia. Journal of the Fisheries Research Board of Canada 28: 1347-1348.
Robins, C. R. [Chairman], R. M. Bailey, C. E. Bond, J. R. Brooker, E. A. Lachner, R. N. Lea, and W. B. Scott. 1980. A list of common and scientific names of fishes from the United States and Canada. American Fisheries Society, Bethesda, Maryland, Special Publication Number 12: 1-174.
Scott, W. B., and M. G. Scott. 1988. Atlantic fishes of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences Number 219: 731 pages.
Accepted 31 May 1991
Status of the Mountain Sucker, Catostomus platyrhynchus, in Canada*
R. E. CAMPBELL 2880 Carling Avenue #1410, Ottawa, Ontario K2B 7Z1
Campbell, R. E. 1992. Status of the Mountain Sucker, Catostomus platyrhynchus, in Canada. Canadian Field-Naturalist 106(1): 27-35.
The Mountain Sucker, Catostomus platyrhynchus, is the most widely distributed member of the subgenus Pantosteus. It is found in the Columbia, Fraser, Saskatchewan and Missouri river systems of Canada as well as the United States where it also occurs in the Green River system and is present in various systems of the Great Basin. Information on the distribution, abundance and life history of the species is limited, but it appears to be less abundant in the northern parts of the range, particularly British Columbia and Washington. A creature of mountain streams, its distribution and ecology is closely relat- ed to the zoogeographic history of the region. The present distribution in relation to historic and present hydrographic fea- tures and fossil evidence suggests that populations may still be expanding in concert with tectonic and orographic pro- cesses, having survived the latest period of glaciation in Columbia and Missouri refugia. Physical and ecological barriers inherent in mountainous habitats give rise to widely separated, genetically diverse populations, the nature of which has led to speculation on the rarity of the species. Although the full extent of the distribution of Canadian populations may not be known there are several widely scattered and diverse viable populations in the west which do not seem to be currently under any threat.
Le meunier des montagnes, Catostomus platyrhynchus, a \a plus grande répartition de toutes les espéces du sous-genre Pantosteus. On peut la trouver dans les systemes des rivieres Columbia, Fraser, Saskatchewan et Missouri au Canada et aux Etats-Unis ot elle habite également le systeme de la riviére Green et divers systemes du Great Bassin. On dispose de peu de données sur la répartition, l’abondance, et le cycle vital de l’espéce, mais elle semble moins abondante dans le secteur septentrional de son aire de répartition, surtout en Columbie-Britannique et dans l’Etat de Washington. Il est un poisson typique des ruisseux de montagnes. La répartition et l’écologie de l’espece sont étroitement liés a histoire zoogéographique de la région. La répartition actuelle relativement aux caractéristiques hydrographiques passées et présentes et aux données obtenues des fossiles porte a croire que les populations slaccroissent de concert avec les processus tectoniques et orographiques. L’espéce a survécu a la derniére période de glaciation dans les refuge des riviéres Colombia et Missouri. Les barriéres physiques et écologiques naturelles des habitats montagneux produisent des populations isolées et différentes au niveau génétique, et ceci a soulevé des conjectures sur la rareté de l’espéce. Quoique |’aire de réparition définitive des populations canadiennes n/’ait pas encore été établie, il existe plusieurs différentes populations viables disper- sées dans l’ouest du pays et qui ne semblent pas étre présentement menacées.
Key Words: Mountain Sucker, Catostomus platyrhynchus, Plains Mountain Sucker, Jordan’s Sucker, Meunier des Montagnes, Catostomidae, suckers, rare fishes.
The Mountain Sucker, Catostomus platyrhynchus (Cope 1874), also commonly known as the Northern Mountain Sucker or Plains Sucker, was long known as Pantosteus jordani Evermann. The mountain suckers in the former genus Pantosteus (now consid- ered as a subgenus of Catostomus) are small suckers of the mountainous regions of western North America. Eight species had formerly been recog- nized in the genus Pantosteus (Bailey et al. 1960), but Smith (1966) reviewed the taxonomy of the group and reduced its status to that of a subgenus of the genus Catostomus. This revision includes five species embracing the previously recognized eight, and an additional species (Catostomus columbianus) previously considered unrelated. Although it does not completely resolve the taxonomic issues in rela- tion to generic status between Pantosteus and
Catostomus, it is generally accepted (Scott and Crossman 1973; Robins et al. 1980).
The Mountain Sucker is the most widely distribut- ed member of the subgenus (Hauser 1969). Scott and Crossman (1973: 548) suggest that, “nowhere is it abundant or widely distributed” in Canada. This report examines the status of the species in Canada as requested by the Fish and Marine Mammal Subcommittee of the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
Description
Mountain Suckers are small catostomids averag- ing 127 to 152 mm total length [TL] (Sigler and Miller 1963). Smith (1966) indicated maximum size in the order of 175 mm standard length (SL), although Hauser (1969) reported seeing an individu-
*Report accepted by COSEWIC 9 April 1991, no status designation required
28 THE CANADIAN FIELD-NATURALIST
al 226 mm TL, and the Royal Ontario Museum (ROM) collection includes a 232 mm male (Figure 1) collected in Alberta in 1964 (ROM 25919). The following account is largely based on descriptive material from Sigler and Miller (1963), Carl et al. (1967), Smith (1966), and Scott and Crossman (1973).
The body is elongate, cylindrical and somewhat compressed caudally. The snout is broad and heavy, the eye small, the mouth large and ventral, the edge of the lower jaw having a sharp-edged cartilaginous sheath and the lower lip has the shape of paired wings (Figure 1). There are definite notches at the corners of the mouth (at the point of lateral connec- tion of the upper and lower lips) and an incomplete medial cleft to the lower lip, which is markedly con- vex anteriorly, with three to five rows of large, round papillae covering the base. The upper lip is large and the outer surface without papillae; there are no teeth in the mouth and the pharyngeal teeth are flat and comblike. There are generally 23 to 37 gill rakers on the external row of the first arch and 31 to 51 on the internal row. The fontanelle is usual- ly reduced to a narrow slit, but may be obliterated; the peritoneum is black or dusky; the intestine is long with six to 10 coils anterior to the liver; there are no pyloric caeca. A two-chambered swimbladder is present, but is reduced, the slender posterior chamber extending to about the point of origin of the pelvic fins. Post-weberian vertebrae number 38 to 44, usually 40 to 43. Cycloid scales cover the body, usually crowded towards the head; the lateral line is complete and straight, the number of scales varying from 60 to 108 throughout the range (79-89 in British Columbia). There is one dorsal fin with eight to 13 soft rays (over the range, 10 or 11 in B.C.); the caudal fin is not long or deeply forked; the anal has seven rays; the pelvics are located well back in line with the middle of the base of the dorsal fin, usually with nine rays and a well developed axillary process; the pectorals are long with 15 rays.
Dorsally, these fish are dark green to grey or brown in colour, usually finely sprinkled with black
Vol. 106
and the ventral surface is pale yellow to white. The lateral line is not prominent, but there is usually a dark green to black lateral band and/or five dorsal blotches of fine black pigment. The fins are virtually colourless, although a faint red tinge may be evident. Young fish have three dark vertical bars and a black peritoneum which may be observed in external observation. Snyder (1983) provides a description (and key) of larvae and early juveniles.
Breeding fish develop an orange to deep red later- al band and the fin rays may become more heavily pigmented. Breeding males also develop minute nuptial tubercles on the entire body surface, and larger tubercles may be found on the lower lobe of the caudal fin, the dorsal surface of paired fins and on the anal fin. Nuptial tubercles may also be found on the breeding females but these are generally smaller and less abundant than in the males. Smith (1966), Hauser (1969), and Scott and Crossman (1973) provide more details.
This species can be distinguished from other catostomids, except Catostomus columbianus, the Bridgelip Sucker, by the incomplete cleft of the lower lip (Figure 1). The notches at the corners of the mouth, the absence of papillae on the anterior vertical surface of the lips and lower scale and fin ray counts may be used to separate it from C. columbianus (Smith 1966; Carl et al. 1967).
Distribution
The range of Catostomus platyrhynchus is con- fined to the fresh waters of mountainous regions in western North America (Figure 2), though they extend to the Cypress Hills in the Canadian prairie. Mountain Suckers occur “in streams of the Great Basin in Utah, Nevada and California; headwaters, North Fork Feather River, California; headwaters of the Green River in Utah, Colorado and Wyoming; parts of the Columbia River drainage in Wyoming, Idaho, Washington, Oregon and British Columbia; Fraser River drainage, British Columbia; upper Saskatchewan River drainage, Saskatchewan and Alberta; Milk River drainage, Montana and
Ficure 1. Mountain Sucker, Catostomus platyrhynchus. Male; 232 mm; ROM 25919; drawing by A. Odum, reproduced from Scott and Crossman (1973) by permission.
1992
FiGurE 2. Approximate North American range of the Mountain Sucker, Catostomus platyrhynchus.
Saskatchewan; upper Missouri River drainage, Montana and Wyoming, and the Black Hills, South Dakota; White River and formerly, possibly, the Niobrara River, Nebraska” (Smith 1966: 60-62).
In Canada, the species has been reported from the South Saskatchewan River in Saskatchewan and Alberta; the Milk River drainage in the Cypress Hills region of Alberta and southwestern Saskatchewan; west in southern Alberta to the Flathead River sys- tem in the Waterton Lakes Region; north along the foothills of the Rockies in streams of the Saskatchewan River System to the North Saskatchewan River (Figure 3) [Scott 1957; Reed 1959; Willock 1969; Scott and Crossman 1973; Atton and Merkowsky 1983]. In British Columbia, the Mountain Sucker has been reported from the Columbia River system, the Similkameen and Tulameen rivers, and Otter and Wolfe creeks; and from the North Thompson (Fraser) River system (Figure 3) [Carl et al. 1967; Scott and Crossman 1973].
Protection
No specific measures are in place for the protec- tion of this species in Canada. General protection, if required, could be afforded through appropriate sec- tions of the Fisheries Act of 1867 (as amended to date). D. E. McAllister (Canadian Museum of
CAMPBELL: STATUS OF THE MOUNTAIN SUCKER 29
Nature, Ottawa, Ontario: personal communication) and Scott and Crossman (1973) indicate that the species may be a rare member of the Canadian fauna.
The Mountain Sucker was listed as a species of special concern in the State of Washington by (Johnson 1987), but not by Williams et al. (1989).
Population Sizes and Trends
Information on this species is mostly limited to presence and absence data. The Mountain Sucker was virtually unknown in Canada prior to 1947 when Dymond (1947) recorded the species from the Cypress Hills Region of southwestern Saskatchewan. There is a previous mention by Eigenmann (1895) of Catostomus griseus [synonymous with Catostomus platyrhynchus (Smith 1966)] from the Swift Current Creek in Saskatchewan, as well as a 1927 ROM record from Belanger Creek (ROM 3891, Appendix III), and a 1928 University of Michigan Museum of Zoology record (UMMZ 164907) from Willow Creek near the border between Saskatchewan and Montana (Smith 1966). The species was first report- ed in Alberta and British Columbia in the 1950s (Scott 1957; Carl et al. 1959). Smith (1966) included a 1956 record from the Bow River (BC 56-516). Paetz and Nelson (1970) state that it was first taken in Alberta by R. B. Miller and C. Word in 1950 from the North Fork of the Milk River. It is doubtless endemic to the Missouri, Saskatchewan, Fraser and Columbia river faunas (Smith 1966; Cavander 1986; Cross et al. 1986; Crossman and McAllister 1986; McPhail and Lindsey 1986), and has probably occu- pied these systems since the last period of glaciation moving northward with the retreating ice front from Missouri and Cascadia refugia [see Hocutt and Wiley (1986) for more details on zoogeography and phylogeny]. They probably went previously unno- ticed because of the lack of directed surveys and the inaccessibility of much of the habitat.
In some parts of its United States range it is abun- dant enough to be readily available as a bait fish. In some states it is used in the manufacture of pet food for feed in fur farming operations (Sigler and Miller 1963). It appears to be less abundant in the northern parts of the range (Scott and Crossman 1973), partic- ularly in Washington, where it is considered to be a species of special concern (Johnson 1987). Mountain Suckers may no longer exist in the Missouri drainage of Nevada, although their former presence there is debatable (Smith 1966). The species is found in some abundance, however, in streams of the Great Basin. Goettl and Edde (1978) reported the Mountain Sucker to be one of the most abundant and widespread fishes found in a Colorado stream.
In Canada, Scott and Crossman (1973) suggested that the species was neither widely distributed nor abundant. McAllister (personal communication) also
30 THE CANADIAN FIELD-NATURALIST
Vol. 106
MCR 94
FiGure 3. Distribution of the Mountain Sucker, Catostomus platyrhynchus, in Canada based on sources cited in the text.
indicated that the species is probably rare in Canada based on is restricted range. However, collection records of the University of Alberta Museum of Zoology, the Canadian Museum of Nature, and the Royal Ontario Museum indicate that from one to 96 specimens were collected at various sites in Alberta during surveys, although it was more common to take less than 20 individuals at a given site. Willock (1969) states that the species is common in the Milk River drainage of Alberta and may be the only species found in the pseudo-alpine habitat of the Sweetgrass Hills. Henderson and Peter (1969) found the species to be abundant and widely dispersed in southern Alberta. B. Carveth (Institute of Animal Resource Ecology, University of British Columbia, Vancouver, B.C.; personal communication) indicates that, although records from British Columbia are scarce, the species is abundant where it has been found.
B. Carveth (personal communication) and others (Smith 1966; Scott and Crossman 1973) also indi- cate that it hybridizes readily with Catostomus columbianus, Catostomus catostomus, the Longnose Sucker, and Catostomus commersoni, the White Sucker, where the species are sympatric. This makes recognition difficult.
Habitat
The Mountain Sucker, like most species of the subgenus Pantosteus, are small catostomids typically associated with the cool waters of mountain streams in areas of moderate current which may occasionally occur in lakes or large rivers (Smith 1966). Their distribution and evolution is closely related to moun- tains; involving adaptation to cool waters, moderate to rapid currents, and rocky substrates. Mountains also are primary barriers, isolating populations and giving rise to variability between populations, through orogenic and tectonic processes. This has
1992
made the taxonomy of the group and the resolution of generic status difficult (Smith 1966).
In Canada, collection records in the Royal British Columbia Museum, Canadian Museum of Nature, and the Royal Ontario Museum, indicate that its habitat is similar to that reported in northern parts of its United States’ range. These fish are usually found in small mountain streams of less than 12 m width and 1 m depth with moderate to swift current, over bottoms ranging from mud, to sand, to gravel and boulders, but usually rubble. Water conditions vary from clear to roiled or turbid; daytime water temper- ature at collection sites is indicated as ranging from 10 to 28°C in summer and near 0°C in winter [see Reed (1962) for water conditions at collection sites in Saskatchewan]. Vegetation found at collection sites includes Pondweed (Potamogeton sp.), Muskgrass (Chara sp.) and algae, Cress (Nasturtium sp.), although macroscopic vegetation is not always present (Smith 1966).
Their occurrence in lakes and larger streams is rare, but they are known to occur in the Yellowstone River in Wyoming, Lower Green River Lake, Wyoming, and Bear Lake, Idaho (Smith 1966). However Erman (1986) found that the relative abun- dance of Mountain Suckers declined in Sagehen Creek, California, after impoundment of the stream to create a reservoir.
In a study of the species in Montana, Hauser (1969) observed that adults tend to favour areas of low velocity (0.5 m/sec) adjacent to pools with bank cover at depths of 1 to 1.5 m. Pierce (1966) noted that this species was usually more abundant below a warm spring. During spawning they utilize riffle areas below pools, returning to the deeper pools after spawning. Young fish, 20 to 35 mm long, prefer areas with moderate current at depths of 15 to 40 cm and are usually found close to an obstruction such as a large rock or submerged log. Larger fish may be found at the margin of runs, retreating to deeper water if disturbed, much the same as for the White Sucker (Stewart 1926). Fingerlings (35 to 135 mm) seem to prefer intermittent side channels with very little discharge and abundant aquatic vegetation at depths of 15 to 50 cm, but are also found in deeper pools (Smith 1966).
General Biology
Very little is known of the biology of the species in Canada and limited knowledge has been obtained elsewhere. Most of the information available on the species has been summarized by Smith (1966) and Scott and Crossman (1973). Most of the following was obtained from these sources as well as from Hauser (1969).
Reproduction: Spawning appears to occur in late spring or early summer when water temperature is above 10.5°C [average range 10.5 to 18.8°C: Scott
CAMPBELL: STATUS OF THE MOUNTAIN SUCKER 31
and Crossman (1973)]. Spawning is usually in riffle areas adjacent to pools of swift to moderate moun- tain streams (see Smith 1966 for a summary of spawning times at various locations). The translu- cent, yellow eggs average 1.5 to 2.2 mm in diameter, and are demersal and adhesive (Hauser 1969; Scott and Crossman 1973). No nest is built, the eggs being scattered over the substrate. The incubation period is not recorded, but is probably in the neighbourhood of 8 to 14 days as reported for other suckers (Stewart 1926; Geen et al. 1966; Scott and Crossman 1973). Hauser (1969) reported spawning in Montana to occur in late June and early July and the earliest dates that fry were seen were 21 June in the Flathead Creek (water temperature 17 to 19°C) and 18 July in
‘the East Gallatin River (water temperature 11 to
19°C).
Fecundity is related to fish length and age, gener- ally older and larger fish bearing more eggs. Hauser (1969) estimated the number of eggs ranged from 990 (for a 131 mm female from Flathead Creek, Montana) to 3710 (for a 184 mm female from the East Gallatin River, Montana). Smaller (approxi- mately 0.5 X) recruitment eggs may also be found in the ovary providing further evidence of a short spawning season for this species; Hickling and Rutenburg (1936) demonstrated that a marked differ- ence in size between mature and recruitment eggs indicates a short spawning season.
Age and Growth: Growth is slow in the environ- ment of cold mountain streams and there is some evidence that the growth rate varies between streams (Hauser 1969). Some fry average 9 mm in July and may reach 30 to 36 mm by mid September. Ninety- five percent have formed the first annulus by mid- June of the following year at about 38 to 60 mm average length (Hauser 1969; Scott and Crossman 973).
Growth is greatest during the first year, the rate of increase decreasing until the third year. After the third year the increment is small, but constant. Mean total lengths (TL) for various ages are given by Hauser (1969) as is an equation for the length-weight relationship.
Hauser (1969) also noted the females are general- ly larger than males and live longer, males living to about seven years of age and females to at least nine, as is generally true for most catostomids (Raney and Webster 1942; Harris 1962; Geen et al. 1966). Smith (1966) indicated that maturity was reached at the end of the second, and in some cases the first, year of life. However, Hauser (1969) found sex differences. Some females matured at age three and all females by age five. Some males matured by age two and all were mature by age four. Early maturing fish are probably also the faster growing fish of any age group (Alan 1959). Mature females range from 90 to
32 THE CANADIAN FIELD-NATURALIST
175 mm and males from 64 to 140 mm (Smith 1966; Hauser 1969).
Diet: Food items consist of algae, diatoms, small invertebrates and microscopic organic matter (Smith 1966). Plants, dipterous larvae and pupae, Closterium and filamentous algae are also important. Turbellaria, Ephemeroptera, Rotifera, and Plecoptera are infrequently eaten (Hauser 1969). The diet sup- ports the hypotheses of Carl et al. (1967) that the horny edges of the jaw are an adaptation for scraping algae off rocks as diatoms and other algae are usual- ly the most abundant food items found in stomach contents (Hauser 1969).
Movements: Little information is available on the movements of this species. Hauser (1969) indicated that adults move from deeper pools in late winter and spring to areas adjacent to the pools in moderate current (0.5 m/sec) and at depths of 1 to 1.5 m with rubble bottoms. During spawning the fish may be found in riffle areas below pools and after spawning they return to deeper pools with bank cover where they are often found in small schools separate from other catostomids. Smaller fish tend to be found around obstructions in areas of moderate current, but retreat to deeper areas if disturbed (Hauser 1969).
Parasites/Predators: The only parasite previously listed for the species was the trematode Posthodiplostomum minimum (Hoffman 1967). However, Evans et al. (1976), Palmieri et al. (1977), and Heckman and Palmieri (1978) recently found metacercariae of the eye fluke, Diplostomum spathaceum, to be widespread in Mountain Suckers and other fishes in Utah. The relative scarcity of par- asites listed for the species probably reflects the degree of investigation rather than a low incidence of parasitic infestations.
Small fish may be utilized by other species, partic- ularly by salmonids (Brook Trout, Salvelinus fonti- nalis, Brown Trout, Salmo trutta, and Rainbow Trout, Oncorhynchus mykiss,) which are often species associates (Goettl and Edde 1978; Erman 1986). Larger fish and spawning adults may be taken by birds and mammals (Scott and Crossman 1973), but their diet probably precludes competition with salmonids.
Behaviour/Adaptability: Very little is known of the behaviour of these fishes. The breeding behaviour (Hauser 1969) and feeding is probably similar to that of other catostomids (Stewart 1926; Brown and Graham 1953; Sigler and Miller 1963; Smith 1966) except that other species may consume more animal matter.
In many parts of the range the species is sympatric with other catostomids such as the White Sucker, Longnose Sucker, Tahoe Sucker (Catostomus tahoensis), Utah Sucker (Catostomus ardens), and
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Catostomus discobolus and hybrids between the species have been recorded (Smith 1966). Although Catostomus platyrhynchus is sympatric with Catostomus columbianus, in the Thompson, Similkameen and Columbia rivers, Smith (1966) indicated that hybrids between the two were not known. However, Carveth (personal communication) has found evidence that the two do hybridize to some extent although the Bridgelip Sucker is more a creature of lakes than streams in British Columbia and associations are not as common as for other catostomids.
Limiting Factors
Physical Factors: The distribution and evolution of mountain suckers is associated with mountains involving ecological adaptations to cool waters, swift currents and rocky substrates. Mountains also provide the major barriers isolating populations. In addition to separation of drainage basins, waterfalls may facilitate unidirectional gene flow. Ecological barriers may also occur due to the environmental dif- ferences in lower parts of streams where the water is warmer, more sluggish and turbid and the bottom substrates are different. Intermittent streams are also characteristic of mountainous areas. Within a given stream system a zone of intergradation may occur along a corridor many kilometres long, but only a few metres wide, and may combine with other fac- tors to effect population isolation to varying degrees.
The linear nature of mountain stream environ- ments has. been the prime determinant of distribu- tion, gene flow, and evolution in the subgenus. Since present distributional limits of this species (and other members of the subgenus) are not coincident with the possible limits defined by current hydrographic limits, the phyogeny is older than recent geographic patterns would suggest (Smith 1966). The early evo- lution and differentiation of Pantosteus probably took place during the Miocene and/or Pliocene in the vicinity of the highland areas of the eastern Great Basin, Colorado Plateau and ancestral Snake and Missouri river headwaters (Hunt 1956; Smith 1966; Minckley et al. 1986).
The subsequent history of Pantosteus is described by Smith (1966) with Catostomus platyrhynchus being best represented in the Great Basin and upper Missouri drainage. That two groups of populations are fairly distinct suggests a long period of isolation. There has been little differentiation of the widely separated populations of the Great Basin indicating a slow evolution. Populations of the Missouri drainage are more similar to populations of the Green, Snake, Columbia, and Sevier rivers and may have inhabited the western Wyoming area for a relatively long peri- od of time, the eastward and northward spread occurring in the late Pliocene early Pleistocene
1992
(Love et al. 1963; Smith 1966). Those of the upper Missouri, Milk and Saskatchewan drainages may represent undifferentiated postglacial derivatives which survived glaciation in a Missouri refugium (Cross et al. 1986; Minckley et al. 1986) and are probably still evolving and expanding their range in conjunction with stream rejuvenation and tectonic processes.
Catostomus platyrhynchus is distributed through- out the entire Columbia system and evidence for a preglacial existence suggests an earlier link with the Snake system (McPhail and Lindsey 1986). Populations below the falls on the Snake River are more similar to those of the Missouri system, while those above the falls have more affinity with those of the Great Basin (Smith 1966). With the retreat of the glaciers, local readvances occurred with the shifting network of drainage connections that is still occur- ring to some extent in interior British Columbia in the alpine and sub-alpine mountainous areas. In the Columbia system, the species occurs in sparse, scat- tered localities as morphologically differentiated forms implying that barriers to gene flow do exist (Smith 1966; McPhail and Lindsey 1986). Populations of the Fraser River system are most like- ly postglacial derivatives from the Columbia River (Smith 1966).
Habitat Perturbations: Erman (1986) provided evidence that impoundments may lead to the extinc- tion of this species in reaches above reservoirs by changing the suitability of the habitat. The introduc- tion of exotic species, agricultural diversions and riparian alterations have also been demonstrated to have negative imact on these fish (Goettl and Edde 1978). Industrial activity and habitat degradation resulting from mineral and fossil fuel exploration and development are also known to have deleterious effects (Goettl and Edde 1978).
Ecological Factors: Populations may be limited to some extent due to predation, particularly by salmonids which may forage on smaller individuals (Goettl and Edde 1978; Erman 1986). Birds and mammals may take some larger fishes during spawn- ing (Scott and Crossman 1973); however, neither of these factors would appear to be leading to declines in most locations. .
Competition with other catostomids could be lim- iting range expansion, but physical barriers are prob- ably more important. Catostomus platyrhynchus is more highly specialized in its feeding and habitat requirements than the White or Longnose suckers or other species of Pantosteus where the ranges overlap (see Smith 1966; Hauser 1969; Scott and Crossman 1973). Dunham et al. (1979) have shown that com- petition with other sympatric catostomids leads to geographic variation in characters such as growth, feeding efficiency, body size and swimming
CAMPBELL: STATUS OF THE MOUNTAIN SUCKER 33
mechanics. Smith (1966) indicated that fish from the same river system may show differences in such characters as width and shape of the caudal peduncle related to current flow and rate.
Special Significance of the Species
The species is fairly isolated in its Canadian distri- bution and is not a well-known member of the Canadian aquatic fauna. Although edible, it is too small to be of economic importance and has never been an important food or sport fish. In the United States, it is often used as a bait fish and as food for fur bearing mammals (Scott and Crossman 1973). Its diet precludes it from being a predator on other fish- es. The taxonomy of the species and the genus is of interest because it reflects evolutionary zoogeograph- ic events and their relation to geological processes.
Evaluation
Catostomus platyrhynchus appears to exist in many widely scattered locations in mountain streams of the Saskatchewan, upper Missouri, Columbia and Fraser river drainages in Canada. Although locally abundant at some localities they are not abundant in Canadian waters where they are at the northern fringe of the range. However, as Carveth (personal communication) indicates, we may not know the true extent of the range. It is probably still expanding in concert with long-term tectonic process. Widely scattered, reproductively viable populations, inherent genetic variability, and the lack of any present threat to most known localities augers well for the contin- ued existence of the species in Canada. The con- struction of the Oldman River dam may, however, threaten populations in that river. Although perhaps rare in relation to other catostomids such as the White Sucker, the species does not appear to be in jeopardy and does not qualify for any COSEWIC category.
Acknowledgments
Financial support for this report was provided through World Wildlife Fund Canada, the Department of Fisheries and Oceans, and the Canadian Wildlife Service. E. J. Crossman and W. B. Scott kindly gave permission for the use of the illustration from Freshwater Fishes of Canada. Thanks are extended to the Canadian Museum of Nature, the Royal British Columbia Museum, the Royal Ontario Museum, to museums at the Universities of Alberta and British Columbia, and to Saskatchewan Parks and Renewable Resources for the provision of collection records and information. I wish also to acknowledge A. E. Peden of the Royal British Columbia Museum and W. Carveth of the University of British Columbia for their helpful comments received through the COSEWIC Fish and
34 THE CANADIAN FIELD-NATURALIST
Marine Mammals Subcommittee, and also all Subcommittee members for their helpful comments and review of the manuscript.
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Bailey, R. M. [Chairman], E. A. Lachner, C. C. Lindsey, C. R. Robins, P. M. Roedel, W. B. Scott, and L. P. Woods. 1960. A list of common and scientific names of fishes from the United States and Canada (Second edi- tion). American Fisheries Society Special Publication Number 2: 1-102. Ann Arbor, Michigan.
Brown, C. J. D., and R. J. Graham. 1953. Observations on the longnose sucker in Yellowstone Lake. Transactions of the American Fisheries Society 83: 38-46.
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Carl, C. G., W. A. Clemens, and C. C. Lindsey. 1967. The freshwater fishes of British Columbia. Fourth Edition British Columbia Provincial Museum Handbook 5. 192 pages.
Cavender, T. M. 1986. Review of the fossil history of North American freshwater fishes. Pages 699-724 in The zoogeography of North American freshwater fishes. Edited by Charles H. Hocutt and E. O. Wiley. John Wiley and Sons, Toronto, Ontario.
Cross, F. B., R. L. Mayden, and J. D. Stewart. 1986. Fishes in the western Mississippi drainage. Pages 363- 412 in The zoogeography of North American freshwater fishes. Edited by Charles H. Hocutt and E. O. Wiley. John Wiley and Sons, Toronto, Ontario.
Crossman, E. J., and D. E. McAllister. 1986. Zoo- geography of freshwater fishes of the Hudson Bay drainage, Ungava Bay and the Arctic Archipelago. Pages 53-104 in The zoogeography of North American fresh- water fishes. Edited by Charles H. Hocutt and E. O. Wiley. John Wiley and Sons, Toronto, Ontario.
Dunham, A. E., G. R. Smith, and J. N. Taylor. 1979. Evidence for ecological character displacement in west- ern American catostomid fishes. Evolution 33(3): 877-896.
Dymond, J. R. 1947. A list of the freshwater fishes of Canada east of the Rocky Mountains, with keys. Royal Ontario Museum of Zoology Miscellaneous Publication Number 1: 1—36.
Eigenmann, C. H. 1895. Results of explorations in west- ern Canada and the northwestern United States. Bulletin of the U.S. Fisheries Commission (1894) 14: 101-132.
Erman, D. C. 1986. Long-term structure of fish popula- tions in Sagehen Creek, California, USA. Transactions of the American Fisheries Society 115(5): 682-692.
Evans, R. S., R. A. Heckman, and J. R. Palmieri. 1976. Diplosomatosis in Utah USA. Proceedings of the Utah Academy of Sciences, Arts and Letters 53(1): 20-25.
Geen, G. H., T. G. Northcote, G. F. Hartman, and C. C. Lindsey. 1966. Life histories of two species of catosto-
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mid fishes in Sixteenmile Lake, British Columbia, with particular reference to inlet spawning. Journal of the Fisheries Research Board of Canada 23(11): 1761-1788.
Goettl, J. P., Jr., and J. W. Edde. 1978. Environmental effects of oil shale mining and processing. Part 1. Fishes of Piceance Creek, Colorado, prior to oil shale process- ing. Ecological Research Series Report, U.S. Environmental Protection Agency, Duluth, Minnesota. Report Number 27: 1—27.
Harris, R. H. D. 1962. Growth and reproduction of the longnose sucker, Catostomus catostomus (Forster), in Great Slave Lake. Journal of the Fisheries Research Board of Canada 19: 113-126.
Hauser, W. J. 1969. Life history of the Mountain Sucker, Catostomus platyrhynchus, in Montana. Transactions of the American Fisheries Society 98(2): 209-215.
Heckman, R. A., and J. R. Palmieri. 1978. The eye fluke disease diplostomatosis in fishes from Utah USA. Great Basin Naturalist 38(4): 473-477.
Henderson, N. E., and R. E. Peter. 1969. Distribution of fishes of southern Alberta. Journal Fisheries Reseach Board of Canada 26(3): 325-338.
Hickling, C. F., and E. Rutenburg. 1936. The ovary as an indicator of the spawning period in fishes. Journal of the Marine Biology Association of the United Kingdom 21(1): 311-318.
Hocutt, C. H., and E. O. Wiley. Chairmen. 1986. The zoogeography of North American freshwater fishes. John Wiley and Sons, Toronto, Ontario. 866 pages.
Hoffman, G. L. 1967. Parasites of North American fresh- water fishes. University of California Press, Los Angeles, California. 486 pages.
Hunt, C. B. 1956. Cenozoic geology of the Colorado Plateau. U.S. Geological Survey Professional Papers 279. 99 pages.
Johnson, J. E. 1987. Protected fishes of the United States and Canada. American Fisheries Society, Bethesda, Maryland. 42 pages.
Love, J. D., P. O. McGrew, and H. D. Thomas. 1963. Relationship of latest Cretaceous and Tertiary deposition and deformation to oil and gas in Wyoming. Pages 196- 208 in Backbone of the Americas, tectonic history from pole to pole. Edited by O. E. Childs and B. W. Beebe. American Association of Petroleum Geologists, Tulsa, Oklahoma.
McPhail, J. D., and C. C. Lindsey. 1986. Zoogeography of the freshwater fishes of Cascadia (the Columbia sys- tem and rivers north to the Sitkine). Pages 53-104 in The zoogeography of North American freshwater fishes. Edited by C. H. Hocutt and E. O. Wiley. John Wiley and Sons, Toronto, Ontario.
Minckley, W. L., D. A. Hendrickson, and C. E. Bond. 1986. Geography of western North American freshwater fishes: description and relationships to intracontinental tectonism. Pages 519-613 in The zoogeography of North American freshwater fishes. Edited by C. H. Hocutt and E. O. Wiley. John Wiley and Sons, Toronto, Ontario.
Paetz, M. J., and J. S. Nelson. 1970. The fishes of Alberta. The Queen’s Printer, Edmonton, Alberta. 281 pages.
Palmieri, J. R., R. A. Heckman, and R. S. Evans. 1977. Life history and habitat analysis of the eye fluke Diplostomum spathaceum, Trematoda: Diplostomatidae in Utah USA. Journal of Parasitology 63(3): 427-429.
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Pierce, B. E. 1966. Distribution of fish in a small moun- tain stream in relation to temperature. Proceedings of the Montana Academy of Science 26: 1—76.
Raney, E. C., and D. A. Webster. 1942. The spring migration of the common white sucker, Catostomus catostomus commersonnii (Lacépéde), in Skaneateles Lake Inlet, New York. Copeia 1942(3): 139-148.
Reed, E. B. 1959. A biological survey of the principal rivers of the Saskatchewan River system in the Province of Saskatchewan, 1957 and 1958. Saskatchewan Parks and Renewable Resources Fisheries Technical Report 59-1: Table 24.
Reed, E. B. 1962. Limnology and fisheries of the Saskatchewan River in Saskatchewan. Fisheries Branch Saskatchewan Department of Natural Resources Fisheries Report Number 6. 48 pages.
Robins, R. C. [Chairman], R. M. Bailey, C. E. Bond, J. R. Brooker, E. A. Lachner, R. N. Lea, and W. B. Scott. 1980. A list of common and scientific names of fishes from the United States and Canada (Fourth edi- tion). American Fisheries Society Special Publication Number 12. 174 pages. Bethesda, Maryland.
Scott, W. B. 1957. Distributional records of fishes in western Canada. Copeia 157(2): 160-161.
Scott, W. B., and E. J. Crossman. 1973. Freshwater fish- es of Canada. Fisheries Research Board of Canada, Bulletin 184. 966 pages. Ottawa, Ontario.
CAMPBELL: STATUS OF THE MOUNTAIN SUCKER 35
Sigler, W. F., and R. R. Miller. 1963. Fishes of Utah. Utah State Department of Fish and Game, Salt Lake City, Utah. 203 pages.
Smith, G. R. 1966. Distribution and evolution of the North American catostomid fishes of the subgenus Pantosteus, genus Catostomus. Miscellaneous Publications of the Museum of Zoology, University of Michigan, Number 129. 132 pages.
Snyder, D. E. 1983. Identification of catostomid larvae in Pyramid Lake and the Truckee River, Nevada. Transactions of the American Fisheries Society 112(2B): 333-348.
Stewart, N. H. 1926. Development, growth and food habits of the white sucker, Catostomus commersonnii, LeSeur. Bulletin of the U.S. Bureau of Fisheries 42: 147-184.
Williams, J. E., J. E. Johnson, D. A. Hendrickson, S. Contreras-Balderas, J. D. Williams, M. Navarro- Mendoza, D. E. McAllister, and J. E. Deacon. 1989. Fishes of North America endangered, threatened, or of special concern: 1989. Fisheries 14(6): 2-20.
Willock, T. A. 1969. Distributional list of fishes in the Missouri drainage of Canada. Journal of the Fisheries Research Board of Canada 26(6): 1439-1449.
Accepted 31 May 1991
Status of the Harbour Porpoise, Phocoena phocoena, in Canada*
DAvID E. GASKIN Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1
Gaskin, David E. 1992. Status of the Harbour Porpoise, Phocoena phocoena, in Canada. Canadian Field-Naturalist 106(1): 36-54.
The Harbour Porpoise, Phocoena phocoena, occurs in both major oceans of the temperate northern hemisphere; it is resi- dent in, or migratory into, the marginal seas except for the Mediterranean and is a summer visitor to the productive fringes of the Arctic Ocean. No surveyed census estimates of population sizes are available in Canadian coastal waters other than for the Bay of Fundy-northern Gulf of Maine, which has a seasonal population of about 4000 to 8000 animals, with a peak period of residency from late July to mid-September. This population, like those on the west coast, in the St. Lawrence and off Newfoundland, is believed to make a seasonal migration of a rather diffuse nature. Although generally regarded as a common species, it is evidently in decline in many parts of its total range. While factors such as increased human distur- bance of coastal regions may be implicated in this decline and increased contamination of the environment may be another factor, the most likely reason for decreasing numbers is the toll exacted by incidental catches in fishing gear, especially groundfish gillnets, coupled with the animal’s very limited reproductive flexibility.
Le Marsouin commun, Phocoena phocoena, vit dans les eaux des deux grands océans de l’hémisphére nord tempéré; on le trouve, a titre de résident ou en période de migration, dans les mers bordiéres, a l’exception de la méditerranée, et il visite pendant l’été les zones limitrophes productives de l’océan Arctique. On ne dispose d’aucune estimation de ses effectifs dans les eaux cotieres du Canada, si ce n’est de celles de la baie de Fundy et du golfe du Maine nord ot sa population saisonniére se situe entre 4000 et 8000 individus environ, avec une période de pointe de fin juillet 4 mi-septembre. Cette population, comme celles de la cote ouest, du Saint-Laurent et des eaux au large de Terre-Neuve, semble effectuer une migration saisonniére de nature assez diffuse. Bien que généralement considéré comme espéce commune, il est évident que le marsouin commun est en déclin dans bon nombre de secteurs de son aire de répartition totale. Certains facteurs, notam- ment une plus grande perturbation des régions c6tiéres due aux activités humaines, et une contamination accrue de |’envi- ronnement, peuvent contribuer a ce déclin, mais la raison le plus probable réside dans les captures accidentelles avec les engins de péche, surtout les filets maillants 4 poissons de fond, de pair avec et la faible capacité d’ adaptation reproductive de cette espéce.
Key Words: Harbour Porpoise, le Marsouin commun, Phocoena phocoena, Cetacea, Odontoceti, Phocoenidae, marine mammals, endangered species.
The adult Harbour Porpoise, Phocoena phocoena (Linnaeus 1758), attains, on average a length of about 1.6 m and a weight of about 50 kg (Figure 1). The snout is bluntly pointed, with no delineated “beak”. The dorsal fin is relatively small and trian- gular, often with an anterior ridge of tubercles. The dorsal surface is dark grey with purplish reflections in life. The chin, variable areas of the flanks, and the ventral surface are white, usually flecked with grey near the dorsal fin. The flippers, flukes and dorsal fin are all dark grey, and there is usually a grey stripe from the eye to the anterior angle of the flipper.
The Harbour Porpoise has an almost circumpolar distribution in the temperate regions of the northern hemisphere (Figure 2). Although most frequently encountered in coastal waters it also occurs over adjacent offshore shallows (e.g., Georges Bank, the Grand Bank, and the Dogger Bank). Because popu-
lations occur around isolated land masses such as Iceland and the Faeroe Islands in the Atlantic (Saemundsson 1939; Gaskin 1984), and the scattered Aleutian Islands in the North Pacific-Bering Sea (Leatherwood et al. 1983), porpoises must occasion- ally cross wide expanses of Open ocean, probably following the rich pelagic feeding zones created by the ocean polar fronts. Perhaps the colonizations of areas such as Iceland resulted when the northward retreat of the semi-permanent ice edges in the late Pleistocene was accompanied by a corresponding northward movement of the polar front (and its asso- ciated fauna) which, during the glacial stadials, was much further south than it is now. There are few confirmed records of this species away from the con- tinental shelf; during CeTAP (Cetacean and Turtle Assessment Program) surveys off the northeastern United States coast for example, only about 0.6% of
*Report accepted by COSEWIC 9 April 1991. Threatened status assigned to the Northwest Atlantic population 10 April 1990 and reconfirmed 9 April 1991; Insufficient scientific information for status designation for the Northeast Pacific population.
36
FIGURE 1. Photograph of a female Harbour Porpoise (89 cm), taken 14 August 1970 by the author.
all Harbour Porpoise sightings were outside the 2000 m depth contour (Winn 1982). Recently how- ever, Stenson and Reddin (1990) reported Harbour Porpoises over deep water in the Newfoundland Basin and the Labrador Sea. The species is notori- ously difficult to sight at any distance in even mod- erate seas, so it can be easily overlooked by inexperi- enced observers.
Gaskin (1984) summarized the hemispheric distri- bution and zoogeography of the Harbour Porpoise based on information collected from 1974 to 1983. The article supplemented the extensive bibliogra- phies provided earlier by Gaskin et al. (1974), Mitchell (1975), Prescott and Fiorelli (1980) and Prescott et al. (1981). More recent information can be found in the volume of abstracts from the pro- ceedings of a conference on cetacean-fishing gear interactions held in La Jolla, California in October 1990, published by the International Whaling Commission (IWC 1990) and in articles by Barlow (1987, 1988), Broekema and Smeenk (1987), Calambokidis (1986), Diamond and Hamon (1986), Gaskin et al. (1984), Gaskin et al. (1985), Gaskin and Watson (1985), Hanan et al. (1986), Kinze (1985a, 1985b), Lansdown (1987), Noldus and de Klerk (1984), Read and Gaskin (1985, 1988), Schulze (1987), Smith and Gaskin (1983), Smith et al. (1983), van Kreveld (1987), Watson and Gaskin (1983), Watts and Gaskin (1985, 1989), Worthy et al. (1987), Yasui and Gaskin (1986) and Yurick and
GASKIN: STATUS OF THE HARBOUR PORPOISE 37
Gaskin (1987, 1988). The monograph by Schulze (1987) has a particularly extensive bibliography, including some European references which may be unfamiliar to many North American workers, and the review by van Kreveld (1987) also contains a num- ber of useful document references often overlooked
FIGURE 2. Global distribution of Phocoena phocoena shown by stippled zones.
38 THE CANADIAN FIELD-NATURALIST
in North American abstracts or not represented in libraries here.
Distribution and Subpopulations
Three major isolated populations exist; in the North Pacific, in the North Atlantic and in the Black Sea-Sea of Azov (Figure 2). These are distinguish- able on cranial meristic and morphometric features (Yurick and Gaskin 1987). Based on data presented by Tomilin (1957) the Black Sea-Sea of Azov ani- mals probably represent a single population with no discernible sub-groups. This population may have been reduced to a critically low level in recent years by over-exploitation, initially by fishermen from the USSR, Bulgaria and Turkey, and more recently, by Turkey alone (IWC 1983, 1984). Yurick and Gaskin (1987) presented evidence for statistically significant cranial differences between the eastern and western North Atlantic populations of the Harbour Porpoise, and indicated that there were also inconclusive data suggesting further segregation of the eastern North Atlantic population into regional sub-populations. Kinze (1985a) concluded that there were highly sig- nificant differences in metric and non-metric cranial characters between animals from the Baltic and the Dutch coast, but not between those from the Baltic and the northeastern North Sea. The present author, however, has some reservations about these results, because Kinze’s regressions do not appear to have been age-corrected and may have been influenced by age-specific catch biases in different samples.
Gaskin (1984) reviewed the somewhat tenuous data concerning possible latitudinal sub-population segregation of Phocoena phocoena in the eastern North Pacific. The species has been recorded from the MacKenzie River delta, Northwest Territories (van Bree et al. 1977), to Los Angeles Harbour. The occurrence of the Harbour Porpoise in the Beaufort Sea is probably not exceptional. Some de facto seg- regation appears probable; studies in Prince William Sound, Glacier Bay and the Copper River estuary (Hall 1979; Matkin and Ray 1980; Taylor and Dawson 1983) point to calving in these waters, and some animals present in all months of the year. Similarly, some animals appear to be resident along the coast of California throughout the year. Infor- mation on ratios of DDE/PCB and HCB/DDE pre- sented by Calambokidis (1986) provides supporting evidence for segregation into subpopulations along this coast. Along the coasts of the northwestern states and British Columbia the species were former- ly regarded as less common south of Washington State than further north (Fiscus and Niggol 1965). Gaskin (1984), after Yurick (1977), tentatively pro- posed two working topographic sub-divisions for the western seaboard; the Bering Sea, and the coast from the Gulf of Alaska to Los Angeles harbour. North- south and inshore-offshore movements are to be
Vol. 106
expected in both these speculative sub-populations, but given the seasonal “territoriality” recorded for some individual Harbour Porpoises (Gaskin and Watson 1985), it is likely that some degree of latitu- dinal segregation is present.
The West Coast of Canada
Within British Columbian waters the Harbour Porpoise was formerly considered to be common up to 20 miles from shore in all areas (Pike and MacAskie 1969). The species appears to have been less commonly sighted in the last two decades in the coastal waters of British Columbia (H. D. Fisher in litt. 1978; I. McTaggart-Cowan, Canadian Committee on Whales and Whaling, 3919 Woodhaven Terrace, Victoria, B.C., personal com- munications), and in the adjacent “Washington Sound” region (Flaherty and Stark 1982). Fisher and McTaggart-Cowan did not collect quantitative infor- mation however.
As far as can be determined, the only concrete distributional data for the Harbour Porpoise on the coast of British Columbia consist of some strand- ings collected by the Royal British Columbia Museum, and a few records from 1987 published by Baird et al. (1988) and regular sightings at one locality by Alex Morton (Echo Bay, Simoon Sound, B.C., personal communication). The localities are shown in Figure 3.
The Estuary and Gulf of the St. Lawrence
The only published account of the distribution and catches of Harbour Porpoises in the St. Lawrence region is that by Laurin (1976). Recently valuable information has been provided by Béland (1988) and Béland et al. (1987), and a survey of incidental cap- tures in Quebec waters is currently being undertaken by the Department of Fisheries and Oceans, Canada. The species was frequently sighted around the Magdalen Islands in the 1950s [H. D. Fisher, (for- merly of) Department of Zoology, University of British Columbia, Vancouver, B.C., personal com- munication], and the author observed Harbour Porpoises off the eastern coast of P.E.I. in July 1974. These data are summarized in Figure 4. Although stranding records often reflect only effort variations in data collection, this figure demonstrates that we do not even know if the species is present in most of the Gulf. It also indicates where even cursory studies would be of value. The westerly limit of this species appears to be the mouth of the Saguenay River; pos- sible reasons for this were discussed by Sergeant (1978).
One of the areas of summer concentration of the Harbour Porpoise in the Gulf of St. Lawrence is Jacques Cartier Passage, between Anticosti Island and northern Quebec. R. Sears and W. Hoek (in litt. 1988), reported seeing large numbers all along this region of the North Shore, with peak abundance in late summer and fall.
1992
FiGuRE 3. Distribution of records of P. phocoena on the west coast of Canada; with the exception of Simoom Sound, these represent confirmed strand- ings only. Major geographical features: A. British Columbia, B. Queen Charlotte Islands, C. Van- couver Island. Specific localities: 1. Sandspit, Morseby Island, 2. Port Hardy, 3. Echo Bay, Simoom Sound, 4. Nootka Island, 5. Flores Island, 6. Tofino, 7. Long Beach, 8. Bamfield, 9. Clover Pt, Victoria, 10. McNeill Beach, Victoria, 11. Gabriola Island, 12. Little Qualicum River, 13. Campbell River, 14. Vancouver, 15. Tsawassen. These records are collated from data supplied by Baird, Nagorsen and Morton (see Acknowledgments).
Baffin Island to Newfoundland
The Harbour Porpoise is commonly recorded on the Greenland side of Davis Strait and Baffin Bay between 61~—67°N (Figure 2) from spring to summer (Kapel 1975, 1977), with the most northerly record probably that from Upernavik at 72°N. On the Canadian side of the Bay, the northernmost limit appears to be Cape Aston at 70°N. Records are more sparse (Mercer 1973) on the Canadian coast because the fishing activity is much less and ice conditions will often keep cetaceans far from land. Furthermore,
GASKIN: STATUS OF THE HARBOUR PORPOISE 39
it is only in recent years that any attempts have been made to collect information on small odontocetes, other than the Narwhal (Monodon monoceros) and White Whale (Delphinapterus leucas), in those waters. The Harbour Porpoise appears to be distribut- ed, at least in certain months, throughout the coastal shelf waters of Labrador and eastern and southeastern Newfoundland (Lien 1983, 1989), and in deeper waters of the Labrador Sea and the Newfoundland Basin (Stenson and Reddin 1990).
The Atlantic Coast of Canada — Cape Breton to southern New Brunswick
This is one of the most-studied populations of the species; a continuous programme of research by the University of Guelph has been in operation since 1969, and earlier work was carried out by Fisher and Harrison (1970). More recently, United States sur- veys have included some transects in Canadian waters. The species probably occurs throughout this area in small numbers in all months of the year. There appear to be no records of significant concen- trations off Cape Breton other than an unpublished observation by G. A. Mertens (Lunenburg, Nova Scotia, personal communication). In University of Guelph surveys in the 1970s the Harbour Porpoise was not found to be nearly as abundant in the sum- mer months along the Atlantic coast of Nova Scotia as in the Bay of Fundy and the northern Gulf of Maine (Figure 5). The majority of the latter animals may move offshore to Georges Bank and adjacent shallows in the autumn; some occur inshore during the winter from New Hampshire to New York, and sometimes as far south as North Carolina (Gaskin 1984) [see section on Species Movement].
Protection
For many years the Harbour Porpoise was afford- ed no protection at all in Canadian waters; despite this, directed hunting for the species was never extensive in modern times. The Harbour Porpoise, like most small cetaceans other than White Whale and Narwhal, went unprotected in Canada because it did not fall within the scope of the Whaling Con- vention Act of Canada, which was in force until 1982. When Canada voluntarily withdrew from the International Whaling Commission, the Convention Act was repealed by Parliament, which then passed into law a substitute set of more broadly defined Cetacean Protection Regulations. These were pro- mulgated in 1982 under the Fisheries Act of Canada, and included all cetaceans. The animal was taken for meat in Newfoundland, and still is in some areas according to Lien et al. (1987), but only in the form of salvaged carcasses from gill nets. The Atlantic coastal communities of Passamaquoddy and Micmac Indians traditionally hunted porpoises, but the prac- tice has almost, if not completely, died out. One hunter in the Beaver Harbour region took the species
40 THE CANADIAN FIELD-NATURALIST
Vol. 106
FIGURE 4. Distribution of records of P. phocoena in the St. Lawrence region; these records are of strandings and confirmed incidental catch reports. Major geographical fea- tures: A. Saguenay River, B. Gaspé Peninsula, C. Anticosti Island, D. Western Newfoundland, E. Magdalen Islands, F. Prince Edward Island, G. Cape Breton Island. Specific localities: 1. Baie Ste-Catherine, 2. Les Escoumains, 3. St. Paul-du- Nord, 4. St. Simeon, 5. St. Flavie, 6. Godbout, 7. Les Mechins, 8. Brochu, 9. Marsoui, 10. Mont-Louis, 11. Petite-Vallee, 12. Carleton, 13. Maria, 14. Forillon, 15. Longue-Pointe, 16. Mingan, 17. Havre Saint-Pierre, 18. Baie-Johan-Beetz, 19. Grande Entree, 20. Hardy’s Channel, 21. Cavendish, 22. Georgetown. These records are taken from Laurin (1976) and more recent data summaries provided by
P. Béland et al. (1987).
to provide meat for his mink farm in the 1950s and early 1960s (Fisher, personal communication). Indians from the Pleasant Point Reserve in northern Maine have sporadically hunted Harbour Porpoises in Canadian waters into the 1980s.
Population Sizes and Trends Pacific Coast
Barlow (1988), using line transect methods during four ship surveys covering 6590 km in September 1984 and May 1986, estimated the total population size of the Harbour Porpoise on the coasts of California, Oregon and Washington as slightly under 50 000 (49 862 + 8891). He noted factors which he believed, could have led to this being an underesti- mate. It is also possible to identify factors, especially latitudinal changes in densities, which could result in
it being an overestimate. There is a strong possibility
of latitudinal shifts in population centres during the course of the year.
Nevertheless, if Barlow’s estimate of mean densi- ty is accepted as a working value and in the process of estimating an overall approximate multiple for shelf area one eliminates from consideration, as did both Barlow (1988) and Watts and Gaskin (1985), narrow shelf regions with strong currents off Vancouver Island, then western Canadian waters might, at least initially, have sustained a population
of some 15 000 to 20 000 animals. This estimate should be regarded with scepticism. Because the species occurs along the coasts of southern Alaska, British Columbia, Washington, and Oregon, the impact of seasonal latitudinal shifts on this estimate are unknown. No recent surveys have been made in western Canadian coastal waters that could be used for crude population estimates, nor are there any data on incidental catch levels or impact.
Atlantic Coast
Gaskin (1977) estimated a population of about 4000 in the Bay of Fundy-northern Gulf of Maine, and Prescott et al. (1981) reported from 2603 to 3456 for approximately the same region. Using more rig- orous techniques Gaskin et al. (1985) estimated the August population in the western Bay of Fundy as 3056 + 1661 in an area of 1969 km?. Watts and Gaskin (1985) estimated the peak population in the Outer Quoddy region only as 1022, closely compara- ble to 1018 to 1270 for the shipboard surveys through the same area by Gaskin et al. (1985). The latter concluded that the total population for the lower Bay of Fundy and approaches could be as high as 7000 to 8000 animals in August, i.e., nearly twice as many as calculated by Gaskin (1977). It should be borne in mind, however, that density estimates which take into account the large “empty” area in the
119.92
Ove
GASKIN: STATUS OF THE HARBOUR PORPOISE 41
Ficure 5. Distribution of records of P. phocoena in the Atlantic region; these records are largely based on quantitative field surveys between 1971-1986. Major geographical features: A. Maine, B. New Brunswick, C. Bay of Fundy, D. Nova Scotia, E. Gulf of Maine, F. Atlantic Ocean. Specific localities in text: 1. Inner Quoddy Region, this comprises Passamaquoddy and Cobscook Bays to the north and west, and Letite Passage, the Western Isles and Head Harbour Passage to the north and east, 2. The Outer Quoddy region, 3. Grand Manan Channel, 4. Grand Manan Island, 5. Digby Gut and Annapolis Basin, 6. The Digby Neck, 7. Brier Island. The closed cir- cles provide a rough representation of densities encountered in summer only. While the species is relatively scarce in the upper Bay of Fundy, the lack of data points on most of the oceanic coast of Nova Scotia indicates only that no surveys have been
made.
lower central Bay of Fundy where Harbour Porpoises are consistently absent for nearly two thirds of the summer (Kraus and Prescott 1981), will yield numbers only in the 4000 to 6000 range.
Kraus et al. (1983) surveyed the coast of Maine from Port Clyde to Cutler in July 1982 and obtained a minimum strip-census estimate of 7956. At this time of year porpoise density would not have attained its maximum in the lower Bay of Fundy. It seems likely that many of the animals seen off Maine would shift northwards by August, since sur- veys in the Boothbay Harbor region of southern Maine in 1971 and 1972 did not find large numbers of animals there (Gaskin, unpublished data). The CeTAP aerial surveys (Winn 1982) recorded only 1800 from Cape Hatteras to the Gulf of Maine, but this has to be a minimum estimate, given the small proportion of time this animal spends at the surface (Watson and Gaskin 1983) and that in an experi- ment, only 14% of porpoises sighted by land-based observers were picked up by an aerial survey crew (Prescott et al. 1981).
The calculated population size of 7956 + 1327 to 15 300 + 2552 (extrapolated by area from the 1982 strip census above) for the eastern seaboard from southern Maine to the New Brunswick border and lower Bay of Fundy would seem a reasonable work-
ing estimate. Even within “high-density” regions, however, there still areas which consistently have few animals. Furthermore, significant distributional shifts can occur, and Kraus et al. (1983) may have overestimated the offshore component beyond the 50 fathom contour. It would be wiser, from the manage- ment and conservation point of view, to accept the lower numbers as conservative population estimates. There are no published population estimates for the waters of Labrador, Newfoundland, or the Gulf of St. Lawrence (Gaskin 1984).
It is possible, however, based upon the well- known relationship of three fisheries population statistics, C (catch size), P (population size) and F (fishing mortality), to attempt some crude estimates of Harbour Porpoise population sizes in the Gulf of St. Lawrence and in the coastal waters of Newfound- land, as suggested to the author by J. Brazil (Newfoundland Department of Environment and Lands, Wildlife Division, St. John’s, Newfoundland, personal communication). The necessary, and proba- bly unrealistic, assumptions for this exercise include: 1) that Harbour Porpoise densities in the Fundy region (where the best data are available), are more or less equivalent to those in the St. Lawrence and around eastern Newfoundland, 2) that the relative catching power of gill nets is also more or less
42 THE CANADIAN FIELD-NATURALIST
equivalent per unit set in each region, 3) that gill net distribution densities are equivalent, and 4) that all segments of the porpoise populations have equal catchability.
For Fundy we have several surveyed estimates of population size for a range of sizes of areas, a rea- sonably well-defined value for the annual incidental catch and from this we can derive a rough estimate for F. In the other regions we have some preliminary estimates for C, and by using the Fundy approxima- tion for F, can derive crude values of P.
As indicated above, Gaskin et al. (1985) estimated the August population of Harbour Porpoises in the western Bay of Fundy to be about 3.0 + 1.6 thou- sands, and Read and Gaskin (1988) reported that the annual catch was of the order of 105 + 10 animals. This yields a range of incidental mortalities from 2.01 to 4.79%. If, as is believed, this population is contiguous with that in the Gulf of Maine, then the population size estimates given by Kraus et al. (1983) for the whole region, and the catch levels estimated by Polacheck (1989) or Kraus et al. (1990) for the whole region, can be used also. These yield mortality values ranging from 280 in a maximum population of 17 852 (1.57%) to 800 or 1000 in a minimum population of 6629 (12.07 to 15.08%), with an approximate average of about 640 out of 12 240 (5.23%). If the population estimates given by Watts and Gaskin (1985) for just the Inner Quoddy region are used in conjunction with the gill net catches from southwestern Fundy only, then we have catches of 95 to 115 in 1022 to 1270 (7.4 to 11.3%). Given the accumulated evidence of changes in char- acteristics of this population (see later sections on Reproductive Biology and Limiting Factors), it seems reasonable to reject values of less than about 4% which would probably not lead to any significant changes (Woodley and Read 1991), as well as the highest which, given the duration of the gill net fish- eries in many areas, should have already led to popu- lation collapse. For purposes of extrapolation to the other two regions, I therefore select a value for F of 5.23%, derived from the averages in the data collect- ed from the Gulf of Maine and the Bay of Fundy by Kraus et al. (1983) and Polacheck (1989). The mini- mum value for C in the Gulf of St. Lawrence is 623, and the maximum perhaps 1500 (Fontaine et al. 1990); these yield crude values for population size within a range of 11 900 to 28 800 animals.
For these coasts of Newfoundland and Labrador, Lien (1989) had an approximate maximum catch estimate of about 3000 porpoises per annum;. using his estimated average of 1800 yields values for P from 34 415 to 57 360, if such catch levels were being sustained. J. Lien (Memorial University of Newfoundland, St. John’s Newfoundland, personal communication) noted, however, that incidental catches and sightings were low in the spring and
Vol. 106
summer of 1990, leading him to believe that a popu- lation crash had already started to occur in New- foundland waters. There are so many imponderables in the data from these regions at present that such population estimates for Harbour Porpoises must be used with the greatest caution.
Habitat
There is no doubt that the Harbour Porpoise is closely tied, in distributional terms, to the major pelagic schooling fish which comprise the bulk of their diet. The Harbour Porpoise is found in the northern hemisphere only, for practical purposes within waters of about 5 to 16°C. Only a relatively small percentage of the total population seems to penetrate Arctic waters of 0 to 4°C. Even in the Black Sea—Sea of Azov, winter temperatures in the southern part are probably 4° to 8°C in most years, and although summer temperatures of up to 25°C are common near the Turkish coast, these are not typical of the upwelling areas near the Crimea where the species probably concentrates during much of the summer. While normally considered an open sea and ocean channel animal the Harbour Porpoise com- monly penetrates rivers and must experience salini- ties down to about 15%o in the Black Sea, and much less in the rivers. It rarely occurs with any frequency in waters less than about 7 to 10 m in depth, unless the bottom is sandy and the current weak; however, it is not common in such conditions because suitable food is usually not abundant. It is generally not often recorded in waters deeper than about 125 m (Barlow 1987, 1988). It is often seen feeding on pelagic schooling fish such as herring and mackerel, but also takes a proportion of hake, squid and octopus in deeper waters of the Bay of Fundy, where it has been frequently caught in groundfish gill nets as deep as 100 m (Read and Gaskin 1988).
The Harbour Porpoise has been recorded in south- ern New Brunswick waters during all months of the year; surface temperatures range from 1 to 3°C in winter to 14 to 15°C in late summer-early fall. Only a few animals appear to winter in the region, but the temperature range encountered may be close to the tolerable lower limit for the species, even if they can increase their feeding rate (Yasui and Gaskin 1986). While the Harbour Porpoise migrates up to latitude 70°N in the eastern waters of Baffin Bay in August, the sea surface temperatures there can range as high as 4°C in that month, and close to 8°C in the south- em part of Davis Strait at 61 to 65°N (U.S. Hydro- graphic Office 1958). The bulk of the Harbour Porpoise population which uses the outer Bay of Fundy during the summer and fall begins to enter the region when surface temperatures are between 8 to 10°C, and abundance usually continues to increase as temperatures rise from 10 to 15°C, depending on local oceanographic conditions, with salinities from
1992)
32 to 34%o. This probably does not imply some kind of physiological limitation, because a Harbour Porpoise in the Otaru Aquarium in Hokkaido, Japan, lives in a tank with several Finless Porpoises (Neophocoena phocoenoides) at 22°C with no sign of difficulties. Rather, the sea temperatures correlate quite closely with the preferred temperature range of the Harbour Porpoise’s main prey in this region, the Atlantic Herring (Clupea harengus).
Watts and Gaskin (1985) were surprised to find that relative abundance of porpoises in the Bay of Fundy during August was inversely correlated with surface temperature distributions, probably as a result of association of Atlantic Herring with verti- cally mixed waters. Because such zones are generat- ed in this region by tidal upwelling processes, they are usually significantly cooler at the surface than the adjacent stratified waters. In general, the Harbour Porpoise tends to be associated with certain oceano- graphic phenomena, such as the zones indicated above, or isolated upwellings, rather than with any particular segment of a parametric range. Zooplankton such as Calanus finmarchicus which are a major prey item for Atlantic Herring (Brawn 1960; Iles 1979; Jovellanos and Gaskin 1983), are concentrated along coastal frontal interfaces. In such areas zooplankton can be 752 more abundant than outside the frontal zone (Pingree et al. 1974). In the interface zones of the Bay of Fundy Calanus fin- marchicus makes up 85 to 96% of the total 2 to 4 mm plankton (Murison and Gaskin 1989). It is not surprising therefore, that Smith and Gaskin (1983) found a strong correlation between copepod density and relative porpoise abundance during their habitat index analyses.
Harbour Porpoises are usually scarce in areas without significant coastal fronts or topographically generated upwellings. On the eastern coasts of Nova Scotia and Prince Edward Island, University of Guelph surveys found them to be far less abundant than in the Bay of Fundy. Yet, even in these areas, a few Harbour Porpoises could usually be found in the lee of an island or archipelagic intrusion where eddies and turbulence provide a zone for passive concentration of zooplankton and usually a feeding and resting place for planktivorous fish. Over rela- tively featureless, shallow sandy bottoms, or over wide channels with mud bottoms and uniform depth such as the Grand Manan Channel, the species is again usually scarce.
Kraus and Prescott (1981: Figure 17), illustrated survey data for Harbour Porpoises in the lower Bay of Fundy and upper Gulf of Maine from mid-June to late October 1980. Their figures clearly show a large area to the east and southeast of Grand Manan, encompassing much of the central region of the lower Bay, in which Harbour Porpoises were almost completely absent, except for the first half of July. R. G. B. Brown, S. Barker, and the author carried out
GASKIN: STATUS OF THE HARBOUR PORPOISE 43
extensive seabird and marine mammal surveys in the same region in 1974 and 1975, with the same results. Only one animal was recorded in the offshore zone, despite the fact that porpoises were locally abundant in Digby Gut and the passages that cut through Digby Neck in western Nova Scotia. In each case, porpoises were concentrated in what might be called “bottlenecks” for pelagic fish movement; zones where the probability of contact with prey was great- ly enhanced. Gaskin and Watson (1985) observed porpoises move directly from one such point to another when foraging off the eastern side of Deer Island in southern New Brunswick. In general, the three main concentration areas in the Fundy region are associated with either major passages, or a large discrete bank with turbulent upwellings (Figure 4).
Variation in abundance can still be quite striking even when one examines two areas where similar topographic and oceanographic conditions prevail. There is little doubt that Harbour Porpoises have the ability to adjust their local distribution patterns by continuously monitoring their environment visually and acoustically and on the basis of previous experi- ence. Watts and Gaskin (1985), observed that por- poises were nearly three times as abundant over ex- tended periods in the mouth of Head Harbour Passage, New Brunswick, as in that of the superfic- ially similar entrance to Letite Passage about 10 km further north. They noted that there appeared to be no difference in abundance of herring of the right size range in the two areas. This difference in por- poise distribution was attributed to topographic dif- ferences in Head Harbour Passage and the Letite approaches. In the former channel, the incoming tidal flow encounters resistance from several large islands and shoals, resulting in stronger and more widespread upwelling than is generated by the gen- tler slopes of Letite Passage (Graham 1933). The mixing in Head Harbour Passage brings into the sur- face layers significant quantities of deep-water plankton which are fed on by herring (Battle et al. 1936). Herring are also carried into near-surface waters by topographic upwelling, since peak tidal currents in the area move faster (Forrester 1958) than juvenile herring are able to swim for prolonged peri- ods (Boyar 1961; Jovellanos and Gaskin 1983), mak- ing herring in Head Harbour Passage much more accessible to feeding porpoises than those within Letite Passage.
Biology Growth and Age
The Harbour Porpoise at physical maturity attains an average body weight of about 54 kg at a standard length of about 155 cm. Females are slightly larger than males at all ages. Both sexes reach maturity ear- lier in the western North Atlantic than in the North Sea. In the former it is attained between three and
44 THE CANADIAN FIELD-NATURALIST
four years of age (Gaskin and Blair 1977); and between five and six respectively for males and females in the North Sea (van Utrecht 1978). For further information, refer to Gaskin et al. (1984) and Read (1990b). The life span of the species is at least 13 years (Gaskin and Blair 1977) in eastern Canadian waters, and 11 years or more in Japanese (and presumably other North Pacific) waters (Gaskin, Yamamoto and Kawamura, 1991). In prac- tice, it is unusual to find many animals, even in rela- tively large samples, more than eight years of age. This led Nielsen (1972) to suggest that formation of osteodentine prevented dentinal layers from being deposited normally after this period, and de Buffrenil (1982) to conclude, from studies of layering in mandibular bone, that the life span was probably in excess of twenty years, as might be expected from the total body weight. Recent studies however, using much larger sample sizes, indicate that de Buffrenil’s technique over-estimates age by a factor of two (Watts and Gaskin 1989), and that animals over eight years of age are simply rather rare in modern- day Harbour Porpoise popuiations.
Yurick and Gaskin (1987) found that sexual dimorphism is present from birth in the Harbour Por- poise, with neonatal skull length greater in the female; this dimorphism persists throughout life. Growth curves and maximum body lengths for both sexes were presented by Gaskin et al. (1984). For further information consult Noldus and de Klerk (1984).
Reproductive Cycle
The exact timing of the reproductive cycle varies slightly from region to region (Gaskin et al. 1984). Mating in most regions occurs between July and August following the majority of births between May and July. In the Fundy region the peak of partu- rition occurs in May. The peak of conception is in June (Read 1990a). Six or seven weeks of pre-im- plantation pregnancy follows conception and foetus- es are first macroscopically detectable in early August (Read 1990a). Growth in early pregnancy is linear and synchronous and the gestation period is about 10.6 months (Read (1990a), although periods as short as nine months have been suggested by ear- lier workers. Neonate growth is rapid and the total duration of lactation is probably about nine months (Read 1990a), but may begin to decrease after about five months (Gaskin et al. 1984; Yasui and Gaskin 1986) despite a bonding between mother and young that may persist for about 18 months before com- plete independence is achieved. There is no evidence to support the existence of the kind of extended lac- tation that occurs in other larger odontocetes such as the Pilot Whale (Sergeant 1962). Calves of Phocoena phocoena show independent behaviour by early autumn, and the first solid food is found in the stomachs when the animals attain a body length of
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about 104 cm (Smith and Gaskin 1974). Moghl- Hansen (1954) recorded finding food in the stom- achs of juvenile animals which he estimated were young of the year of about five months of age.
The presence in the Harbour Porpoise of propor- tionately large testes, a long penis, females larger than males, and little apparent social structure (Gaskin 1982), suggests that sperm competition is part of the basic reproductive strategy in this species, as in some other cetaceans and other orders of mam- mals (Ralls 1976; Brownell and Ralls 1986).
Studies of seasonal testis volume, diameter of seminiferous tubules and the presence or absence of
‘spermatogenesis provides strong evidence of a sea-
sonal male sexual cycle (Gaskin et al. 1984), some- thing not found in larger odontocetes (Best 1969). This may be related to sperm competition, but also to selection for efficiency and economy of tissue weight and function in what is, after all, the smallest cold water cetacean. The active testes are exception- ally large in this species; in the average sexually active adult male they may together weigh more than 2 to 3 kg, compared with a total body weight of about 50 kg (Gaskin et al. 1984).
Mohl-Hansen (1954) found a very high (84%) pregnancy rate in adult females taken in the Danish winter drive fisheries (n = 111); a sharp contrast to the much lower rate reported by Gaskin et al. (1984) from the Bay of Fundy. Recent information (Read 1990b) shows that in September to October the per- centage of pregnancies rises dramatically in the Fundy females, suggesting that the previous data obtained was biased by the early sampling period (May to August). Read (1990b) concluded that in the early and mid-August samples from Fundy, the event was not advanced enough to be detected by the rou- tine gross necropsy then used. Alternatively, a frac- tion of the pregnant females may move into the region only in early autumn. Most female porpoises probably give birth every year (Read 1990b). Post- partum pregnancies in the Fundy region exceed 62% in most years, according to a preliminary assessment of the new data, paralleling the findings of Mghl- Hansen for the Baltic population.
Species Movements
A pattern of migration is apparent in most popula- tions of the Harbour Porpoise, but it generally has to be derived from data on relative presence and absence in different seasons in specific adjacent areas. Radio-telemetry (Gaskin et al. 1975; Read and Gaskin 1985) has to-date only provided information on short-term movements but enough to indicate that although some animals may demonstrate seasonal home-range behaviour, others may wander for tens of kilometers within a day or so, and may or may not return to the area of release.
Apparent movements of Harbour Porpoises in Newfoundland-Labrador were summarized by
1992
Gaskin (1984). The species is common in the Trinity Bay region only from May to July. The rela- tive timing of occurrence in the Gulf of St. Lawrence and the Bay of Fundy suggests that the Newfoundland population is distinct, and the sup- position is that it goes further north in summer. Given the spring concentrations off eastern New- foundland and Labrador, the late summer concentra- tions that occur off West Greenland in August- September, and the absence of summer sightings off eastern Newfoundland or on the northern Labrador- Baffin Island coasts, there seems a strong circum- stantial case for considering Newfoundland- Labrador and West Greenland to be different sea- sonal zones of occupation of a single migratory pop- ulation. This conclusion has been reinforced by Stenson and Reddin’s (1990) discovery of animals out in the Labrador Sea. Summer ice distribution is probably a major limiting factor in occurrence on the western side of the Strait (M. C. Mercer, Department of Fisheries and Oceans, St. John’s, Newfoundland, personal communication).
An eastward and offshore movement into the mid- stream and eastern region of the St. Lawrence during the late autumn and early winter months has not been fully documented, but must occur as the range in the western region becomes restricted by falling water temperatures and ice formation in some areas. There are no data on possible seasonal movements of Harbour Porpoises on the Atlantic coast of Nova Scotia, other than an unpublished report by G. A. Mertens that they can be seen off St. Ann’s Bay region in May, moving towards the Gulf.
The Bay of Fundy-northern Gulf of Maine popula- tion, as indicated earlier, attains peak numbers in July-September. No large concentrations have been recorded further south along the coast of Maine in late fall or early winter. The CeTAP surveys (Winn 1982) revealed a dispersed population in this period, spread out from the northern Gulf of Maine, past Cape Cod to the vicinity of Long Island. Kraus (New England Aquarium, Boston, Massachusetts, personal communication) reported some moderate concentra- tions sighted during aerial surveys of Georges Bank in May. Banks such as this, with surface tempera- tures of 8 to 10°C along their southern and offshore margins, and possessing ample stocks of fish during all months of the year, may provide important win- tering grounds for Harbour Porpoises. Almost all stranding records for the coastline from New York to North Carolina are from winter months. There are also a few stranding records from eastern Florida (A. J. Read, Department of Zoology, University of Guelph, Guelph, Ontario, personal communication). Similarly, the Harbour Porpoise can be regarded as primarily a late autumn-early spring component of the marine mammal fauna of the New Hampshire coast (S. Mercer, personal communication). It is
GASKIN: STATUS OF THE HARBOUR PORPOISE 45
rarely recorded there between June and early September. In the absence of results from tag returns, it cannot be shown conclusively that these are the seasonal movements of a single population, but the indirect and circumstantial evidence is rea- sonably compelling.
Limiting Factors
Cetaceans, with their single calf, and post-partum oestrus occurring in a significant number of individ- uals in some species, including the Harbour Porpoise, have little flexibility in their reproductive cycle to compensate effectively for additional mor- tality. The only density-dependent responses which seem feasible for this species in the presence of suf- ficient food are increases in juvenile growth rate and slight reduction in the age in sexual maturity. The number of young cannot feasibly increase (twins occur with a frequency of about 0.028 in some whale populations, but there is little direct evidence to sug- gest that both survive), and the length of the individ- ual reproductive cycle cannot be shortened.
The Harbour Porpoise’s general reliance on schooling fish of commercial importance as major prey items puts it in a position of direct competition with fishing industries in the regions where the dens- est concentrations of such species occur. Given the above constraints, over-exploitation of several prey species simultaneously could indirectly lead to a rapid decline in Harbour Porpoise reproductive and recruitment success.
Fortunately, directed hunts by coastal fishermen taking this species for meat and oil are now very lim- ited, and many of the animals caught in eastern North American and European herring weirs and pound nets and Japanese coastal salmon traps are released alive. Mortalities from these sources are small.
It is evident that the Harbour Porpoise populations are in trouble in several parts of the northern hemi- sphere; it has virtually disappeared from much of the Baltic Sea (Andersen 1972; Kinze 1985a), the Black Sea (IWC 1982, 1983), and is very likely declining rapidly in the southern North Sea and the English Channel (Evans 1987; van Kreveld 1987). The pri- mary factor in the case of the Black Sea decline was directed hunting by fishermen from the USSR and Turkey, in other areas the major culprit is almost cer- tainly incidental catches by groundfish gill nets, although there was a large directed catch in Danish waters in the 1940s (Mghl-Hansen 1954). Entrapments in United Kingdom waters were reviewed by Northridge (1990), in Swedish waters by Lindsted (1990), and in Portugal by Sequeira (1990).
The salmon drift net fishery killed at least 1500 per annum in the early 1970s off West Greenland (Lear and Christensen 1975). Stenson and Reddin
46 THE CANADIAN FIELD-NATURALIST
(1990) reported catches in drift nets during experi- mental salmon tagging that ranged from 0.01 per nautical mile of net per hour off West Greenland in summer to 0.14 in the Newfoundland Basin in spring.
There are now data for the coast of Labrador; Lien (1983) initially recorded a few animals in fish- ing gear in the vicinity of Red Bay, and concluded that catches were likely to be significantly greater than the records indicate, largely because of a reluc- tance by fishermen to report incidental entrapments. After analyzing data from a survey made in 1982 using log books and interviews, it was evident that catches were indeed much larger; the known kill from 28 harbours (out of a total of 80) was 111 ani- mals in 1982, but the annual average, excluding very large catches in the Square Islands area, was at least 160, and the total could in practice be much higher (Lien 1989). Lien (1983), and Pratt and Nettleship (1987) reported large catches in the southeastern part of Newfoundland, mostly from gill nets in the inshore cod fishery. In this region the catches are made almost entirely in June and July. Lien et al. (1987) tabulated 24 specimens taken in those months in 1987, all but one from groundfish gill nets; his survey results (Lien 1989) indicated that catches in this region are large, at least in the hundreds per year, and possibly in the low thou- sands.
Laurin (1976) reported that gill netters along the south shore of the St. Lawrence took an unspecified number each year. Recently an assessment of the magnitude of the problem in this region has been ini- tiated by the Department of Fisheries and Oceans (Fontaine et al. 1990). In 1988 the minimum number reported was 623 Harbour Porpoises taken in fishing gear on the north and south shores of the St. Lawrence; Fontaine and his co-workers estimated that the real catch was probably at least twice this.
The history of gill net entrapments of Harbour Porpoises on the west coast from Alaska to Washington was summarized by Gaskin (1984). The serious threat posed by high levels of gill net catches from a demonstrably rather small population off the coast of central California has been provided by Hanan et al. (1986), Heyning et al. (1990) and Jefferson et al. (1990). Gearin et al. (1990) studied the impact of a Chinook Salmon (Onchorhynchus tshawytscha) set net fishery in the western Strait of Juan de Fuca and on the north coast of Washington State in 1988 and 1989; 102 kills were recorded in 1988 and 27 (with much less fishing effort) in 1989.
The gill net catches of Harbour Porpoises in New England coastal waters were summarized by Gaskin (1984); the extent and size of the catches in recent years has been discussed by Hoyt (1989). Read and Gaskin (1988) presented data on the catches from the Bay of Fundy gill net industry during the mid-1980s,
Vol. 106
while Kraus et al. (1990) and Payne et al. (1990) reported on those from the nearshore waters of the northeastern United States. The Bay of Fundy—Gulf of Maine area is the only region where sustained studies have been made. The conclusions drawn by Read and Gaskin (1988) and Read et al. (1990) are not reassuring. A whole series of symptoms of popu- lation numerical decline and changes in juvenile growth and the age at sexual maturity is evident (Read 1990b; Read and Gaskin 1990). The gill net catch of porpoises per boat declined from 5.5 in 1986 to 4.6 in 1987 to 3.8 by 1988. The catch per boat in the inshore (Campobello Island) region dropped even more drastically, from about 5.0 to 1.3 in 1988. The catch and total effort in each of these seasons has fluctuated, but the implication is strong that the inshore harbour porpoise population is being significantly reduced by the incidental catches. While surveyed densities in the offshore area north of Grand Manan have not changed, probably because of the contagious distribution always found on pre- ferred feeding grounds, a decline in the coastal waters of Deer Island and in adjacent areas such as Back Bay and Letite, was documented by Gaskin and Watson (1985) as starting about 1974. Identification of a primary cause was confounded by a coincident drop in surface temperatures which sug- gested oceanographic changes might be involved. Mean summer temperatures have risen again since 1978, but without a concurrent return of porpoises to the area. Survey effort off Deer Island has been much reduced in the last few years until 1990, but qualitatively replaced by local whale watching oper- ations. T. Beatty (Sunbury Shores Nature Centre, St. Andrews, New Brunswick, personal communica- tions) reported sighting only about eight animals during the whole 1988 season, and perhaps a dozen in 1986 and 1987. This decline was confirmed by R. Bosein (Captain, University of New Brunswick
_ Research Vessel, Cummings Cove, Deer Island,
West Isles, New Brunswick, personal communica- tion). This inshore region was previously document- ed as being particularly frequented by mothers with new calves (Smith and Gaskin 1983). In the 1970s from 20 to 100 animals might be expected to be seen in a single day. Watson and Gaskin (1985) noted a number of recognizable individuals returning to the Fish Harbour region of Deer Island each year. The former habit of mainland gill netters of setting nets in a line across about a third of the approaches to Deer Island, with the nets across Head Harbour Passage covering perhaps another third, may well have been killing animals of this inshore “deme” faster than others were learning to utilize the area. Further indications of changes in population struc- ture are: (1) an increase in the mean length of calves at specific weeks in the season in comparison to ear- lier years, (2) a measurable decrease in the age at
1992
sexual maturity, (3) the virtual disappearance of large (155 cm+) animals in the samples of the 1980s, and (4) the similar virtual absence of animals more than eight years of age (Read and Gaskin 1990). A greater proportion of the females now appear to be maturing at three years of age than in the study made by Gaskin and Blair (1977), although these data are still equivocal and require larger sample sizes. This may not be a classic density-dependent response, as might generally be supposed, but rather a reflection of a shrinking reproductive component of the popu- lation being composed of a high proportion of primi- parous females.
The most parsimonious explanation for this evi- dent decline is the impact of Fundy gil! net kills (c. 100 per year on average), coupled with weir deaths (c. 15/year), on a population which is almost cer- tainly the same as that which winters off southern New England (Gaskin 1984) where it is subjected to gill net kills estimated at 280 to 800 per annum (Polacheck 1989). Kraus et al. (1990) believed that the real value is nearer 1000 per year.
The dynamics of population growth in phocoenid porpoises was investigated by Barlow (1986), based largely on the reproductive parameters summarized by Gaskin et al. (1984) and re-evaluated by Woodley and Read (1991) using additional data from the Fundy region in the late 1980s. Based on the most realistic of three models of Harbour Porpoise popu- lation growth presented by Woodley and Read (1991), and given the restrictions of one young per year, a probable neonate natural mortality of about 0.41, and the relatively late maturity and short life span, the maximum rate of annual production could not possibly exceed 10%. Given that natural mortali- ty will continue, it is doubtful if the real rate of replacement could exceed 4%. Woodley and Read (1991) contended that this species was unlikely to sustain even an annual incidental mortality of 5%. Natural mortality might even be increased by contin- ued periodic massing of predators such as sharks [as was documented by Brodie and Beck (1983) in the case of Sable Island Grey Seals] to prey on specific seasonal aggregations of a population shrinking in absolute size. Given also that the best conservative estimate for the Fundy-northern Gulf of Maine popu- lation by Kraus et al. (1983) was 7956 + 1327 and that the annual incidental kill is probably in excess of 600 animals per year, then the population is almost certainly in decline even if we accept the upper range limit for population size. At the lower range limit, which is closer to the 4000 estimated by Gaskin (1977), the decline will be much steeper.
The impact of organochlorine hydrocarbons on reproduction in cetaceans remains largely unknown, although Otterlind (1976) and Wolff (1981) have in part attributed reproductive disorders in these ani- mals to high PCB concentrations in tissues. No gross
GASKIN: STATUS OF THE HARBOUR PORPOISE 47
disorders have been noted by the University of Guelph group during some 350 necropsies between 1969 to 1988, but the levels of organochlorine residues in the Fundy-Gulf of Maine population are documented as being some of the highest in the world (Gaskin 1985) and in 1976 these were on the rise again after declining in blubber of Harbour Porpoises between 1969 and 1973 (Gaskin et al. 1982). If organochlorines are responsible for repro- ductive disorders in small cetaceans, the Fundy-Gulf of Maine Harbour Porpoise population would be a prime candidate.
Trade and Exploitation
There is little evidence of past or present trade in Phocoena phocoena or its products, although Tressler (1923, not seen: referred to by Mitchell 1975) described the export of salted porpoise meat from northern Norway at that time. The species has not been found to be a suitable animal for seaquaria, although a few animals have been displayed in their countries of origin, e.g., Denmark and Japan. Possibly some meat has been traded at times between coastal Indian communities in Canada and the United States. Gilpin (1875) described a thriving Mic-Mac fishery for the Harbour Porpoise off the Fundy coast of Nova Scotia in the last century. This fishery is believed to have started in the late 18th century (Mitchell 1975). The Passamaquoddy Indians of northern Maine took a few animals each summer by shooting, at least into the 1980s. Animals taken fresh from gill nets may be eaten in some coastal communities in New Brunswick, Quebec, Newfoundland, and Labrador (Lien 1983; Gaskin 1984). It is also taken for food in Greenland (Kapel 1975) and in Iceland (Saemundsson 1939). Major drive fisheries used to exist in Denmark (M@ghl- Hansen 1954) and it was also taken in directed fish- eries in Poland (Ropelewski 1957). There are no data for past Bulgarian exploitation of Harbour Porpoise in the Black Sea, but Jelescu (1960) documented activities in coastal waters of Romania, and the impact of catches by the USSR and Turkey (IWC 1983, 1984) were referred to earlier in this review. Scheffer and Slipp (1948) and Mitchell (1975) reported catches of Harbour Porpoises by coastal Indian communities in the Pacific Northwest states.
Special Significance of the Species
The Harbour Porpoise is a well-known pelagic predator in the upper trophic level of the coastal food web in northern temperate latitudes. It has special significance because it is the smallest of the cold- water marine cetaceans, and therefore of particular scientific interest for studies on marginal bioenergetic economics and natural selection pressures. Beyond this, it has potential value as an indicator species; it is still generally regarded as a common animal, but is
48 THE CANADIAN FIELD-NATURALIST
actually one which is manifestly becoming much less common in several major portions of its range (IWC 1983; van Kreveld 1987). Such a clear warning signal cannot easily be ignored by government agencies responsible for coastal shelf management; it becomes obvious that some serious dysfunction is present in the system. In this case the decline is in large part the result of the virtually uncontrolled use of groundfish gillnets in many countries.
Because the Harbour Porpoise is near the top of the coastal food web and has a large fat store to function as a reserve and for thermo-regulatory pur- poses, it becomes a mobile storage vat for just about every kind of lipophilic organic chemical contami- nant that finds its way into coastal waters. While there are many problems inherent in the accurate interpretation of such residues (Aguilar 1985), the general patterns of the stored compounds provide a reasonable toxicological overview of which com- pounds might merit particular attention. Further- more, because the species has such a wide range in the northern hemisphere, it can be used for compara- tive studies across continental ranges, not just from one relatively local region to another. For example, while it is evident that organochlorine levels are lower in Newfoundland waters than in the Fundy region (Gaskin et al. 1982), they are also much lower in northern Japanese waters than in western North American or western European coastal regions.
Evaluation
The true population status of the Harbour Porpoise is unknown throughout most of the coastal waters of Canada. In all areas it has been subjected to inciden- tal catches of unknown magnitude by gill nets. In the one area where the problem has been systematically examined over several years, Bay of Fundy-New England, the impact would seem to be serious. There is evidence of a change in population structure and some population decline in the inshore waters over about 15 years, which became much more evident in 1986 to 1988. Given the known limited reproductive flexibility of the species and the similarity of this developing pattern to that already recognized in European waters, it is strongly recommended that the status of the Harbour Porpoise along the Northwest Atlantic coast of Canada remain as threatened; there
is however, insufficient scientific evidence to desig-
nate a status for the Canadian population in the Northeast Pacific, although I would suspect it is vul- nerable.
Acknowledgments
A review of this kind cannot be made successfully without the assistance and cooperation of many. I would like to extend sincere thanks to those who gave advice, comments and in some cases, unpub- lished data: R. W. Baird of Victoria, British
Vol. 106
Columbia; P. Béland, Institute National d’ecotoxi- cologie du Saint Laurent, Rimouski, Québec; the late M. Bigg, Department of Fisheries and Oceans, Nanaimo, B.C.; D. Goodman, Fisheries Research Branch, Department of Fisheries and Oceans, Ottawa, Ontario; W. Hoek, Department of Fisheries and Oceans, Mont Joli, Québec; R. Reeves, of the Arctic Biological Station, Ste-Anne-de-Bellevue, Québec; Dr. J. Lien, Department of Psychology, Memorial University, St. John’s, Newfoundland; D. Nagorsen, Royal British Columbia Museum, Victoria, B.C.; Ms. A. Morton, Echo Bay, Simmom Sound, B.C.; A. J. Read, Department of Zoology, University of Guelph, Guelph, Ontario; R. Sears, Mingan Islands Research Station, Sept-Iles, Québec; R. Bosein, Cummings Cove, Deer Island, New Brunswick; T. Beatty, Sunbury Shores, St. Andrews, N.B.; H. D. Fisher, formerly of the Department of Zoology, University of British Columbia, B.C.; I. McTaggart-Cowan, Victoria, B.C.; and G. A. Mertens, Lunenburg, Nova Scotia. Thanks are also extended to R. R. Campbell, Department of Fisheries and Oceans, Ottawa, Ontario; W. Hoek, J. Brazil of the Newfoundland Wildlife Division, St. John’s, Newfoundland, J. Lien and two anonymous review- ers, whose constructive advice was most useful and appreciated during the development of the final ver- sion of the manuscript.
Funding in support of the production of the report was made possible through contributions from The Department of Fisheries and Oceans and World Wildlife Fund (Canada).
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