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Category Archives: Extirpated Species


COSEWIC – Assessment and Status Report on the Atlantic Salmon, Salmo salar, Lake Ontario population in Canada, Extirpated 2006

Recent hydro proposals would represent a widespread privatization of Ontario’s rivers. One striking result of an earlier era of privatization of Ontario’s rivers was the construction of dams that degraded water quality, disrupted flows, and led to the extirpation of the Atlantic Salmon from Lake Ontario.

The COSEWIC report on this population concludes that

“Approximately 40 tributaries of Lake Ontario were known to support runs of Atlantic salmon. Scales obtained from two adult museum specimens indicate an exclusively freshwater growth history, suggesting that the salmon that originally inhabited Lake Ontario was most likely a [completely] freshwater form.

 “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. …prior to its extirpation, the Atlantic salmon abounded in the tributaries of Lake Ontario. …The last native salmon was thought to have been caught in 1898.

“Many conditions contributed to the decline and ultimate disappearance of the salmon in Lake Ontario; however, most are attributable to the settlement of the basin and the alteration of habitat by timbering, agriculture, dams for mills, and the fishing industries.

“Perhaps of greatest consequence to Atlantic salmon populations over their global range has been the construction of mill and driving dams for the timber trade, as well as dams for tanneries, carding mills and gristmills. These dams were typically built with no provision for fish passage so salmon were prevented from reaching their native spawning grounds. The fish congregating at the base of the dams were vulnerable and more easily captured by fishermen. In many instances, this resulted in complete elimination of runs of Lake Ontario Atlantic salmon.”

Download the entire COSEWIC report.


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