Deepwater sculpin
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| Myoxocephalus thompsoni Girard, 1851 |
The deepwater sculpin (Myoxocephalus thompsoni) is a freshwater sculpin that inhabits the bottoms of cold, deep freshwater lakes of northern North America. Its distribution ranges from the Great Bear Lake of Canada to the Great Lakes. It is a designated at-risk fish species in Canada, protected as a species of Special Concern under Canada's Species at Risk Act.
The deepwater sculpin is generally gray-brown with mottling on its head, back, and sides with a whitish underside. When full-grown, they are usually between 4 and 6 inches (10–15 cm) and weigh less than an ounce (<25 g). They are a bottom-feeding species, which makes them vulnerable to a build-up in contaminants in polluted lakes. They were considered extinct in Lake Erie and Lake Ontario, but have recently been rediscovered there. They mostly eat tiny crustaceans and aquatic insects and are eaten by lake trout and other predatory fish.
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[edit] Distribution
The distribution of the Deepwater Sculpin is almost entirely limited to Canada with the exception of the American Great Lakes and a few inland lakes in Michigan and Minnesota. In Canada, its distribution is patchy and limited to cold, deep lakes in areas that were formerly glaciated or with proglacial lake connections. This includes the Gatineau region through the Laurentian Great Lakes, Manitoba and Saskatchewan and northward to Great Bear and Great Slave lakes in the Northwest Territories. An isolated population also exists in Waterton Lake, Alberta. Designated at risk (Special Concern) are the Great Lakes-Western St. Lawrence populations, which are found in only 10 lakes in eastern Canada. In Ontario, this fish occurs in lakes Nipigon, Ontario, Superior, Fairbank, Huron and Erie. In Lake Erie, only larvae (young-of-the-year) have been observed. In Quebec, it occurs in Lac des Iles and in Roddick, Thirty-one-Mile and Heney lakes. Populations in Heney Lake and Lac des Iles are in decline or may even no longer exist.
[edit] Habitat and Life History
The Deepwater Sculpin is a bottom-dwelling fish that is found in cold (<5ºC), well oxygenated, deep lakes. In the Great Lakes, adults usually live between 60 and 150 m in depth. For this reason, not much is known about the biology of this fish. The reproductive cycle is not well understood and the time of spawning is not known. Age of maturity has been estimated at three years for females and two for males. It appears that individuals from the Great Lakes, especially Lake Ontario, are generally larger compared to other populations. The Deepwater Sculpin is also likely preyed upon by deepwater Lake Trout (Salvelinus namaycush).
[edit] Diet
The diet of Deepwater Sculpin consists largely of Mysis relicta, Diporeia spp. and chironomid larvae. Zooplankton likely comprise the diet of the larval stage, which is pelagic (open water).
[edit] Threats
The Deepwater Sculpin is likely impacted by changes in zooplankton species composition and abundance. For example, a decline in Diporeia spp. in the lower Great Lakes may pose a threat to this fish since it is an important food source. In addition, the enrichment of lakes with nutrients (eutrophication) and the resulting low oxygen levels in bottom waters likely contributed to the decline of the Deepwater Sculpin in Heney Lake and Lac des Iles.
[edit] Similar Species
The freshwater and marine forms of the Fourhorn Sculpin (M. quadricornus) are two closely related taxa that resemble the Deepwater Sculpin. However, they have four horn-like spines on top of the head, which are lacking in the Deepwater Sculpin.
[edit] References
- "Myoxocephalus thompsoni". FishBase. Ed. Ranier Froese and Daniel Pauly. 10 2005 version. N.p.: FishBase, 2005.
- Myoxocephalus thompsoni (TSN 167323). Integrated Taxonomic Information System. Retrieved on 12 June 2006.
- COSEWIC Status Report 2006
[edit] External links
- Deepwater Sculpin Fact Sheet from New York State Department of Environmental Conservation
- Royal Ontario Museum fact sheet
- Department of Fisheries and Oceans fact sheet
