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COSEWIC assessment and status report on the Atlantic Salmon (Lake Ontario population) in Canada
- Assessment Summary
- Executive Summary
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status Designations
- Summary of Status Report
- Technical Summary
- Information Sources
- Biographical Summary of Report Writer
- Appendix A.
- Appendix B
Population Sizes and Trends
Observations of the historical population levels of Atlantic salmon in Lake Ontario have been largely based on anecdotal information rather than discrete population estimates. However, the large numbers of Atlantic salmon in Lake Ontario began to show marked decline in number in the mid-1800s and were no longer present before 1900 (Parsons 1973, Scott & Crossman 1973). The colonization of Upper Canada in the late 1700s led to the demise of the Atlantic salmon in Lake Ontario. As recounted by Lady Simcoe, prior to 1800, the rivers and creeks abounded with salmon; however, during the ensuing years settlers fished heavily with nets and spears and erected dams at the mouths of rivers to support growing industry, all to the detriment of the salmon (Dunfield 1985). Although there are no early population estimates, anecdotal accounts suggest that, prior to its extirpation, the Atlantic salmon abounded in the tributaries of Lake Ontario. One resident of the Credit River area stated that around 1810 “salmon…swarmed the rivers so thickly that they were thrown out with a shovel and even with the hand" (Simcoe, Diary). There seems, however, to be no evidence that when salmon were abundant in streams discharging into Lake Ontario, they were also abundant in the upper part of the St. Lawrence River (Huntsman 1944).
Samuel Wilmot reported in 1879 that for some years previous to 1868, scarcely any Atlantic salmon could be found in the streams tributary to Lake Ontario (Wilmot 1879). The last native salmon was thought to have been caught in 1898 (Dymond 1965, Carcao 1986, Scott & Crossman 1973).
There have been several attempts to strengthen, and now to re-establish, a population of Atlantic salmon in Lake Ontario since the 1866 when Samuel Wilmot established his hatchery in Newcastle, Ontario (Dunfield 1985, Dymond 1965). At first, the stocking effort had a distinct effect on the salmon population, as population increases were recorded in many Lake Ontario tributaries. By 1879, however, the number of salmon observed in the streams was falling to the point that, in1881, Wilmot is reported as stating that "only a half dozen adult fish and a few dirty discoloured grilse" were seen (Dymond 1965).
In the 1940s, the Ontario Department of Lands and Forests attempted to re-establish Atlantic salmon in Duffin Creek using eggs from Miramichi River stock (Bisset et al. 1993). However, mortalities due to high summer stream temperatures and predation shortly after stocking dampened the effect of this stocking attempt as juveniles were only observed in the stream for two years (McCrimmon 1950).
In 1987, the Ontario Ministry of Natural Resources (OMNR) initiated an experimental stocking program. The objective of the program was to re-establish Atlantic salmon in one or more tributaries of Lake Ontario and to provide a sport fishery based on naturally reproducing populations and supplemented by stockings of hatchery-reared fish (Bisset et al. 1993). Returns of stocked fish were much lower than expected. In 1995, OMNR established a formal plan to investigate the feasibility of restoring self-sustaining populations of Atlantic salmon to the Lake Ontario basin (Bisset et al. 1995). The plan was designed to systematically explore the factors considered to be most important to the successful restoration of self-sustaining populations. Benchmarks for each life stage were set in order to measure progress towards meeting the goals and objectives of the plan. Current stocking by OMNR (see Appendix A) is in support of scientific studies to evaluate stream habitat suitability and species interactions.
In 1983, the New York State Department of Environmental Conservation (NYSDEC) launched an Atlantic salmon restoration program with the objective to restore a self-sustaining spawning stock in New York tributaries yielding at least 2 smolts/100 yd2 of suitable rearing habitat by 1990 (Abraham 1983). During the late 1980s, Atlantic salmon became a small but consistent component of the lake fishery. Although growth of the adult salmon returning to the study streams was excellent, natural reproduction was non-existent (Eckert 2003). In 1990 the Atlantic salmon program changed from a small-scale experimental project with a stocking target of 50,000 yearlings/year to a larger put-grow-take program (target of 200,000 yearlings/year) that would support a trophy sport fishery (Eckert 2003). Returns of Atlantic salmon failed to meet the expectations of the expanded stocking program. Due to continuing poor returns of stocked fish, NYSDEC has further reduced its Atlantic salmon stocking program (Eckert 2003).
Although the stocking efforts in Lake Ontario to date have been successful in securing a limited number of Atlantic salmon in Lake Ontario and its tributaries, self-sustaining populations have not been established, and there is no discernable evidence of natural reproduction.
Although Atlantic salmon are not native to the other Great Lakes, stocking programs have been initiated by both the U.S. government and non-governmental agencies in Lakes Huron, Michigan and Superior (Appendix B). There has been no evidence of natural reproduction in any of these lakes (pers. comm., OMNR Lake Biologists: J. Bowlby, D. Reid). Although spawning activity has been observed in the St. Marys River population, no definitive evidence of natural reproduction or subsequent recruitment has been documented (Roger Greil, Aquatic Research Laboratory, Lake Superior State University, Sault Ste. Marie, MI).
There is a non-anadromous population in Trout Lake, near North Bay, Ontario that is naturally reproducing (Maraldo et al. 1997). Atlantic salmon were first introduced to this lake in 1935 through stocking of fish from the Lac St-Jean area of Quebec (Maraldo et al. 1997). Following a significant spill of zinc into Four Mile Creek in 1967, the principal spawning creek of the system, Atlantic salmon were extirpated from Trout Lake. Salmon fingerlings from the Ontario Ministry of Natural Resources, North Bay hatchery were re-introduced to the lake in 1989, and by 1995, low but viable numbers of naturally reproduced Atlantic salmon were captured during electro-fishing surveys (Maraldo et al. 1997).
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