Research Document - 2013/084
Recovery Potential Modelling of Western Silvery Minnow (Hybognathus argyritis) in Canada
By J.A.M. Young and M.A. Koops
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) had assessed the Western Silvery Minnow (Hybognathus argyritis) as Endangered in Canada (2008). Here we present population modelling to assess allowable harm, determine population-based recovery targets, and conduct long-term projections of population recovery in support of a recovery potential assessment (RPA). Our analyses demonstrated that the dynamics of Western Silvery Minnow populations are particularly sensitive to perturbations that affect survival of immature individuals (from hatch to age 2), or the fecundity of first time spawners. Harm to these portions of the life cycle should be minimized to avoid jeopardizing the survival and future recovery of Canadian populations. Based on an objective of demographic sustainability (i.e., a self-sustaining population over the long term), we propose a population abundance recovery target of 12 000–236 000 adult Western Silvery Minnow, requiring 25–497 ha of suitable habitat. In the absence of mitigating efforts, additional harm or habitat limitations, we estimate that a growing Western Silvery Minnow population will take approximately 9 years to reach this recovery target if starting from a population of 1200 adults. Recovery strategies which incorporate improvements in the most sensitive vital rates of the Western Silvery Minnow will have the greatest effect on population growth.
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