Are lake trout that hatch on Lake Ontario’s rocky shoals the offspring
of wild, or hatchery-reared parents?
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| Fisheries biologist holding a lake trout. Photo: Matt Garvin |
This is one of the questions in the minds of Canadian and U.S. biologists as they trawl 11 Lake Ontario locations, collecting fish from four different lake depths using deep and mid-water survey techniques. Tissue samples from the wild fish caught will reveal their genetic origins — whether the parents were hatchery-reared fish or naturally-occurring lake trout. When all survey data is combined, the international team will know if naturally-occurring lake trout are on the rise.
Lake trout were once the top predator fish species in Lake Ontario, but by the 1950s they seemed to vanish, victims of over-fishing, especially in the 1920s and 1930s. They had also suffered from the harmful effects of shoreline and industrial development and invasive species, such as the parasitic sea lamprey.
Beginning in the 1970s, international partners worked hard to control aquatic invaders, to improve water quality by controlling industrial pollution and agricultural runoff, and to restore the lake trout fishery through stocking. Then, in the 1990s, survey crews began observing small numbers of wild lake trout. The hope has grown that, as more wild lake trout reach maturity, their populations will increase. Perhaps one day we will see naturally-reproducing populations of lake-spawned fish establish themselves in a significant way from Hamilton Harbour east to Cape Vincent.
The challenge then will be to continue protecting lake trout by controlling new invasive species, such as the round goby and spiny water flea.
Click here to view a map of the project area
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Lake Trout – An Indicator Species
Lake trout are long-serving indicators of ecosystem health. They live for about 20 years and are slow-growing and late-maturing. And, like the coal miners’ canaries, their well-being reflects a healthy environment:
• If lake trout have been present for some time, chances are their habitat is clean and unpolluted. The species requires clean substrate for spawning and, to thrive, must have deep, cold, well-oxygenated waters.
• Lake trout are a top-level predator. Their presence indicates that the food chain below them is probably well-ordered, varied and healthy.
Basin-wide, lake trout are especially useful indicators because they’re the only salmonids native to every one of the Great Lakes.
Project Partners and Sponsors
- Great Lakes Fishery Commission
- Ontario Ministry of Natural Resources
- New York State Department of Environmental Conservation
- United States Geological Survey
- United States Fish and Wildlife Service
For more information, contact:
- Alastair Mathers, Lake Ontario Basin Canada-Ontario Agreement Coordinator, Lake Ontario Management Unit, Ministry of Natural Resources, Picton (613) 476-8733
- Ted Schaner, Fisheries Assessment Biologist, Lake Ontario Management Unit, Ministry of Natural Resources, Picton (613) 476-2746