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COSEWIC assessment and status report on the American Eel in Canada

Assessment Summary


Assessment Summary – April 2006

Common name: American Eel

Scientific name: Anguilla Rostrata

Status: Special Concern

Reason for designation: Indicators of the status of the total Canadian component of this species are not available. Indices of abundance in the Upper St. Lawrence River and Lake Ontario have declined by approximately 99% since the 1970s.  The only other data series of comparable length (no long-term indices are available for Scotia/Fundy, Newfoundland, and Labrador) are from the lower St. Lawrence River and Gulf of St. Lawrence, where four out of five time series declined.  Because the eel is panmictic, i.e. all spawners form a single breeding unit, recruitment of eels to Canadian waters would be affected by the status of the species in the United States as well as in Canada.  Prior to these declines, eels reared in Canada comprised a substantial portion of the breeding population of the species.  The collapse of the Lake Ontario-Upper St. Lawrence component may have significantly affected total reproductive output, but time series of elver abundance, although relatively short, do not show evidence of an ongoing decline.  Recent data suggest that declines may have ceased in some areas; however, numbers in Lake Ontario and the Upper St. Lawrence remain drastically lower than former levels, and the positive trends in some indicators for the Gulf of St. Lawrence are too short to provide strong evidence that this component is increasing.  Possible causes of the observed decline, including habitat alteration, dams, fishery harvest, oscillations in ocean conditions, acid rain, and contaminants, may continue to impede recovery.

Occurrence: Ontario, Quebec, New Brunswick, Price Edward Island, Nova Scotia, Newfoundland-Labrador, Atlantic Ocean

Status history: Designated Special Concern in April 2006.  Assessment based on a new status report.