Lake Superior commercial fishing operators are interested in a deep water-dwelling subspecies of lake trout called siscowet, which is rich in Omega-3 fatty acid.
Fisheries technician holding a siscowet, a deep-water subspecies of the lake trout. Photo: Stephen Chong/MNR
Fisheries managers want to know: How much can be harvested without causing long-term harm to Lake Superior siscowet populations? The answer to this question will determine if harvesting siscowet for their Omega-3 fatty acid content is economically feasible.
In anticipation of this new fishery, Canadian and U.S. agencies are studying the ecological role of the siscowet in Lake Superior, including the species’ age ranges, size structure, growth rate, reproductive capacity and abundance. The study uses data collected from standardized netting surveys carried out by agencies around the Lake Superior basin. Over the course of this three-year project, Ministry biologists sampled 66 sites across Lake Superior’s Ontario waters. They caught over 3,700 fish, nearly 2,000 of which were siscowet or their leaner cousins, the lake trout.
Click here to view a map of the project area
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The Siscowet Rules Offshore in Lake Superior
• The siscowet is the most abundant predator fish in Lake Superior. It dominates Superior’s offshore waters where depths exceed 80 metres (262.5 feet). Because the siscowet was not as susceptible to lamprey, its numbers remained relatively high during the decline of lean lake trout in the late 1940s.
• The siscowet is physically different from its sleeker and more colourful cousin the lean lake trout. It is more gray-looking, with a deep, robust body high in fatty tissue. As with other species, siscowet fatty tissue absorbs and retains contaminants, such as mercury, dioxin, PCBs and chlordane. The high fat levels and contaminants make them less desirable for eating. But siscowet could become a commercially desirable species if their oils can be purified.
Project Partners:
- Department of Fisheries and Oceans Canada
- Great Lakes Fishery Commission
For more information, contact:
- Steve Chong, Assessment Biologist, Upper Great Lakes Management Unit, Ministry of Natural Resources, Sault Ste. Marie (705) 253-8288, Ext. 273
- Marilee Chase, COA Lake Superior Basin Coordinator, Upper Great Lakes Management Unit – Lake Superior, Ministry of Natural Resources, Thunder Bay (807) 475-1371