Lake Sturgeon, Acipenser Fulvescens, in a Large Canadian River
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COSEWIC Assessment and Status Report on the Lake Sturgeon Acipenser fulvescens Western Hudson Bay populations Saskatchewan-Nelson River populations Southern Hudson Bay-James Bay populations Great Lakes-Upper St. Lawrence populations in Canada Western Hudson Bay populations - ENDANGERED Saskatchewan-Nelson River populations - ENDANGERED Southern Hudson Bay-James Bay populations - SPECIAL CONCERN Great Lakes-Upper St. Lawrence populations - THREATENED 2017 COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows: COSEWIC. 2017. COSEWIC assessment and status report on the Lake Sturgeon Acipenser fulvescens, Western Hudson Bay populations, Saskatchewan-Nelson River populations, Southern Hudson Bay- James Bay populations and Great Lakes-Upper St. Lawrence populations in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xxx + 153 pp. (http://www.registrelep- sararegistry.gc.ca/default.asp?lang=en&n=24F7211B-1). Previous report(s): COSEWIC 2006. COSEWIC assessment and update status report on the lake sturgeon Acipenser fulvescens in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 107 pp. (www.sararegistry.gc.ca/status/status_e.cfm). Houston, J.J.P. 1986. COSEWIC status report on the lake sturgeon Acipenser fulvescens in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-32 pp. Production note: COSEWIC would like to acknowledge Cam Barth, Patrick Nelson and Craig McDougall of North/South Consultants Inc. for writing the status report on the Lake Sturgeon (Acipenser fulvescens), in Canada, prepared under contract with Environment and Climate Change Canada. This report was overseen and edited by Nicholas Mandrak, Co-chair of the COSEWIC Freshwater Fishes Specialist Subcommittee. For additional copies contact: COSEWIC Secretariat c/o Canadian Wildlife Service Environment and Climate Change Canada Ottawa, ON K1A 0H3 Tel.: 819-938-4125 Fax: 819-938-3984 E-mail: ec.cosepac-cosewic.ec@canada.ca http://www.cosewic.gc.ca Également disponible en français sous le titre Ếvaluation et Rapport de situation du COSEPAC sur sur L’esturgeon jaune (Acipenser fulvescens), populations de l’ouest et de la baie d’Hudson, populations de la rivière Saskatchewan et du fleuve Nelson, populations du sud de la baie d’Hudson et de la baie James et populations des Grands Lacs et du haut Saint-Laurent au Canada. Cover illustration/photo: Lake Sturgeon — Provided by authors. Her Majesty the Queen in Right of Canada, 2017. Catalogue No. CW69-14/484-2017E-PDF ISBN 978-0-660-09191-4 COSEWIC Assessment Summary Assessment Summary – April 2017 Common name Lake Sturgeon - Western Hudson Bay populations Scientific name Acipenser fulvescens Status Endangered Reason for designation This is one of the largest, longest-lived, freshwater fish species in Canada and has special significance to Indigenous Peoples. Over three generations, the distribution and abundance of mature individuals has declined dramatically, largely as the result of harvesting and dams, which have not ceased. Occurrence Saskatchewan, Manitoba Status history The species was considered a single unit and designated Not at Risk in April 1986. When the species was split into separate units in May 2005, the "Western populations" unit was designated Endangered. In November 2006, when the Western populations unit was split into five separate populations, the "Western Hudson Bay populations" unit was designated Endangered. Status re-examined and confirmed in April 2017. Assessment Summary – April 2017 Common name Lake Sturgeon - Saskatchewan-Nelson River populations Scientific name Acipenser fulvescens Status Endangered Reason for designation This is one of the largest, longest-lived, freshwater fish species in Canada and has special significance to Indigenous Peoples. Formerly assessed as five separate designatable units, recent genetic evidence indicates that those populations should be treated as a single unit. Harvesting and dams were the main reasons for historical declines. Although some populations appear to be recovering, this species is not yet clearly secure. Occurrence Alberta, Saskatchewan, Manitoba, Ontario Status history The species was considered a single unit and designated Not at Risk in April 1986. When the species was split into separate units in May 2005, the "Western populations" unit was designated Endangered. In November 2006, the Western populations unit was split into five separate populations. In April 2017, the Winnipeg - English River, Red-Assiniboine Rivers - Lake Winnipeg, Saskatchewan River, Nelson River, and Lake of the Woods - Rainy River populations were considered a single unit and this 'Saskatchewan - Nelson River populations' unit was designated Endangered. iii Assessment Summary – April 2017 Common name Lake Sturgeon - Southern Hudson Bay – James Bay populations Scientific name Acipenser fulvescens Status Special Concern Reason for designation This is one of the largest, longest-lived, freshwater fish species in Canada and has special significance to Indigenous Peoples. Some populations are impacted by harvesting and dams, some populations exist in pristine environments, and there are likely many populations yet to be discovered in this remote area. If not mitigated, future development may negatively impact the species. Occurrence Manitoba, Ontario, Quebec Status history The species was considered a single unit and designated Not at Risk in April 1986. When the species was split into separate units in May 2005, the "Southern Hudson Bay - James Bay populations" unit was designated Special Concern. Status re-examined and confirmed in November 2006. Status re-examined and confirmed in April 2017. Assessment Summary – April 2017 Common name Lake Sturgeon - Great Lakes – Upper St. Lawrence populations Scientific name Acipenser fulvescens Status Threatened Reason for designation This is one of the largest, longest-lived, freshwater fish species in Canada and has special significance to Indigenous Peoples. The main reasons for historical declines in most populations, harvesting and dams, are clearly reversible and understood, but have not ceased in all populations. Some populations appear not to have been severely impacted and some populations appear to be recovering but are not yet secure. Occurrence Ontario, Quebec Status history The species was considered a single unit and designated Not at Risk in April 1986. When the species was split into separate units in May 2005, the "Great Lakes - Upper St. Lawrence populations" unit was designated Special Concern. Status re-examined and designated Threatened in November 2006. Status re-examined and confirmed in April 2017. iv COSEWIC Executive Summary Lake Sturgeon Acipenser fulvescens Western Hudson Bay populations Saskatchewan-Nelson River populations Southern Hudson Bay-James Bay populations Great Lakes-Upper St. Lawrence populations Wildlife Species Description The Lake Sturgeon is one of five sturgeon species found in Canada. It is one of Canada’s largest freshwater fishes. Lake Sturgeon has a pointed snout, ventral protrusible mouth, four barbels in front of the mouth, five rows of bony scutes, and a heterocercal tail. Special Significance The Lake Sturgeon has a rich historical significance to First Nations peoples and was also commercially harvested across much of the species’ range between the late-1800s and mid-1900s. The St. Lawrence River in Quebec supports the only remaining commercial fishery. Aboriginal fisheries are ongoing. Caviar, made from Lake Sturgeon eggs, is still highly prized. Lake Sturgeon is also sought by trophy anglers (where permitted; predominantly catch-and-release) in many locations. Distribution The Canadian range stretches from the North and South Saskatchewan rivers in Alberta in the west, to the St. Lawrence River estuary in the east, and from various rivers that empty into Hudson Bay in the north to several boundary waters (e.g., Rainy River, Great Lakes) in the south. Designatable Units Based on the national freshwater biogeographic zones used by COSEWIC and supplemental genetic information, four designatable units were identified: DU1 - Western Hudson Bay; DU2 - Saskatchewan-Nelson River; DU3 - Southern Hudson Bay-James Bay; DU4 - Great Lakes-Upper St. Lawrence. v Habitat The range of the Lake Sturgeon spans four freshwater biogeographic zones and six terrestrial ecozones. The species occupies a wide variety of aquatic ecosystem types (e.g., stepped-gradient Boreal Shield rivers, low-gradient meandering Prairie rivers, low gradient Hudson lowland rivers, Great Lakes and associated tributaries). Habitat Requirements Lake Sturgeon requires a variety of habitats to complete its lifecycle, and the species has evolved to exploit typical upstream to downstream hydraulic and substrate gradients. Spawning habitat is typically characterized by fast-moving water found at the base of falls, rapids, or dams. Hatch is contingent on aeration by flowing water, after which larvae apparently require gravel substrate in which to bury and remain while development continues. Once the yolk sac is absorbed, larvae drift downstream via water currents. Habitat requirements at the age-0 stage are not well understood, but may not be as strict as previously assumed. Aside from the requirement of adequate benthic prey items, the habitat requirements for middle to later life stages (juveniles and adults) are not particularly narrow. Habitat Trends