Exploring uncertainty in population viability analysis and its implications for the conservation of a freshwater fish

Abstract

Abstract A spatially explicit metapopulation viability model was created within RAMAS‐GIS to address questions related to the conservation and management of a freshwater species at risk (Notropis anogenus). Population viability analysis was conducted to evaluate extinction risk and sensitivity analyses were undertaken to identify the most important spatial and non‐spatial parameters influencing extinction and decline. As biodiversity offsets are increasingly used to compensate for habitat loss, the population model was also used to explore the effectiveness of four potential offsetting mechanisms. In particular, this study addressed whether the impact of habitat loss on a species at risk could be compensated by: (i) increasing habitat elsewhere; (ii) increasing vital rates; (iii) increasing abundance; and (iv) increasing connectivity. Results suggest that extinction risk is low for this metapopulation and that the risk of extinction was most sensitive to vital rates. Compensating habitat loss with habitat gain, the most straightforward approach explored, was by far the most effective type of compensation. Increasing vital rates was the second most promising approach. Although increasing abundance and increasing connectivity could not be categorically ruled out, their effectiveness was much more limited. Overall, this study provided insight into the influence of spatial and non‐spatial parameters on abundance, patch occupancy, and extinction risk of an aquatic species. This approach can be applied to a wide variety of species to evaluate the effect of ecosystem perturbations and inform management options.