|Photo: © Tim Haxton|
Features: The Lake Sturgeon, Acipenser fulvescens, is unlike any other fish found in Ontario. This unusual fish exhibits several notable features: it has five rows of bony plates arranged along the back and sides; the skin is covered with tiny toothlike projections that give it the feel of fine sandpaper; and the dorsal fin is fairly large and located just forward of the tail, which is unequally lobed like that of a shark. In typical appearance, the belly of the Lake Sturgeon is white or light-coloured and contrasts with the darker back and sides; overall, colour is uniform in adults whereas younger fish may appear blotchy.
Like catfish, the Lake Sturgeon is a specialized bottom feeder: its triangular snout has four long, hairlike appendages on the underside called barbels, which are used for sensing its surrounding environment and detecting food. During feeding the visibly toothless mouth, located behind the food-sensing barbels, forms a tube that is thrust forward along the bottom and sucks up food. A wide variety of organisms are consumed including insect larvae, crayfish, molluscs and small fish.
The Lake Sturgeon is Canada’s largest freshwater fish species: past records exist of specimens exceeding 2 m in length and 136.5 kg in weight, although most mature specimens seen today are much smaller. It usually inhabits the bottoms of shallow areas of large freshwater lakes and rivers, but migrates each year from early May to late June to swift-flowing water to spawn. Individuals usually return to the same spawning rivers year after year. Quebec data suggest the maximum age to be 55 years for males and 80 years for females, although the oldest recorded Lake Sturgeon in Ontario, caught in 1953 in Lake of the Woods, had lived for an astonishing 154 years.
Status: Special Concern Provincially
Range: Historically, the Lake Sturgeon was found across an expansive range in North America. Today, Canadian populations occur west to the North Saskatchewan River in Alberta, and east to Cap Brűlé, Quebec in the St. Lawrence River, a location that represents the approximate termination of freshwater in the St. Lawrence River. To the north, it is found as far as Fort George River in Quebec on the eastern side of James Bay, and the Seal River on the western side of Hudson Bay just north of Churchill, Manitoba. In Ontario, the Lake Sturgeon is found in all the Great Lakes, and in all drainages of the Great Lakes and of Hudson Bay. In the United States, this fish has disappeared from a large portion of its former range, although it can still be found south to the states of Mississippi, Alabama and Arkansas.
Threats: Five of eight populations of Lake Sturgeon recently identified for Canada are listed as Endangered, and one is listed as threatened. The decline in numbers witnessed today partially reflects human over-exploitation in the latter half of the nineteenth century. At present, it is likely that over-harvesting for meat and caviar forms a significant threat to the Lake Sturgeon. Additional threats include the construction of dams, which may disrupt habitat and interrupt spawning movements and timing; habitat degradation resulting from human activities; habitat contamination caused by chemicals, toxins, and fertilizers; and the introduction of non-native species that include competing and predatory fishes, and plants that may modify habitat.
Protection: Internationally, the Lake Sturgeon is listed on Appendix II of the Convention for International Trade in Endangered Species of Wild Fauna and Flora (CITES). In Canada, the Lake Sturgeon and its habitat are managed by each province under regulations of the federal Fisheries Act. In addition, all Canadian Lake Sturgeon commercial fisheries have been subject to special regulation, which has resulted in closed fisheries, quota reductions, and negotiated agreements to limit fishing of this species.
Text Sources: Harkness and Dymond 1961; Scott and Crossman 1998
Last Modified Date: June 2008
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