Research Document - 2013/135
Recovery Potential Assessment for the American Eel (Anguilla rostrata) for eastern Canada : description and quantification of threats
By G. Chaput, T.C. Pratt, D.K. Cairns, K.D. Clarke, R.G. Bradford, A. Mathers, and G. Verreault
Abstract
This document addresses the Terms of Reference for the Recovery Potential Assessment associated with the identification and assessment of threats to American Eel for eastern Canada. The first section describes the general threat categories with a focus on relating the activities, factors and the stress which can act on American Eel mortality or productivity. Where possible, the causal mechanism linking the stress factor and the population vital rate are described. This serves as the basis for describing the causal certainty that links a threat and its associated activities to the population dynamics of the American Eel. The second section of the document describes how the level of concern of the threats is qualified, by determining the magnitude (severity), extent (spatial), frequency (temporal) and causal certainty of each threat to American Eel. In the third section, the level of concern of threats is assessed for five jurisdictions in eastern Canada (province of Ontario, province of Quebec, Newfoundland and Labrador, southern Gulf of St. Lawrence, Atlantic coast of Nova Scotia/ Bay of Fundy). Common threats which score as medium or high level of concern across the regions include directed commercial fisheries for American Eel, and physical obstructions. Region specific threats, not shared across all regions, include turbine mortality (within physical obstruction category), habitat alterations, introduction of the swim bladder parasite, and changes in ecosystems mostly associated with non-native species introductions and spread. Climate factors primarily acting in the ocean environment are considered to be important in determining the abundance of American Eel and are treated as a limitation to population recovery rather than a threat.
- Date modified: