A Practical Comparison of Viability Models Used for Management of Endangered and Threatened Anadromous Pacific Salmonids

Abstract

AbstractThis study considered whether different population viability analyses give similar estimates of extinction risk across management contexts. We compared the performance of population viability analyses developed by numerous scientific teams to estimate extinction risk of anadromous Pacific salmonids listed under the U.S. Endangered Species Act and challenged each analysis with data from 34 populations. We found variation in estimated extinction risk among analytical techniques, which was driven by varying model assumptions and the inherent uncertainty of risk forecasts. This result indicates that the scientific teams developed techniques that perform differently. We recommend that managers minimize uncertainty in risk estimates by using multiple models tailored to the local ecology. Assessment of relative extinction risk was less sensitive to model assumptions than was assessment of absolute extinction risk. Thus, the former method is better for comparing population status and raises caution about conclusions regarding absolute extinction risk.Received October 18, 2012; accepted July 3, 2013