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The Demise of American Eel in the Upper St. Lawrence River, Lake Ontario, Ottawa River and Associated Watersheds: Implications of Regional Cumulative Effects in Ontario
Abstract.—American Eel mortality has increased substantially over the past century due largely to significant cumulative effects of fishing and fish passage through hydro-electric turbines across their range. Nowhere has this been more pronounced than in waters of the St. Lawrence River, Lake Ontario, Ottawa River and associated watersheds. We illustrate this by examining the cumulative effects of hydroelectric facilities on eels migrating downstream through the Mississippi River and Ottawa River, and outline further impacts eels encounter en route to spawn in the Sargasso Sea. The probability of a mature female eel surviving its emigration through the Mississippi and Ottawa River to the upper St. Lawrence River is estimated to be as low as 2.8% due to turbine mortalities alone (2.8–40%). Mortality risk increases as the eel attempts to run the gauntlet of fisheries in the lower St. Lawrence River and the probability of out-migration survival is estimated to be as low as 1.4%. Some mortalities could be mitigated through improved application of existing laws, development of policy requiring consideration of cumulative effects and improved integration among program areas responsible for sustainable management of fisheries, biodiversity, dams and hydro-electric facilities. We recommend changes to policy, procedures and internal organizational structures provided with clear directions, and call for increased accommodation of Aboriginal perspectives.
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MacGregor, R., T. Haxton, L. Greig, J. M. Casselman, J. M. Dettmers, W. A. Allen, D. G. Oliver, and L. McDermott. 2015. The demise of American Eel in the upper St. Lawrence River, Lake Ontario, Ottawa River and associated watersheds: implications of regional cumulative effects in Ontario. Pages 149–188 in N. Fisher, P. LeBlanc, C. A. Rose, and B. Sadler, editors. Managing the impacts of human activities on fish habitat: the governance, practices, and science. American Fisheries Society, Symposium 78, Bethesda, Maryland.
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