What Are the Odds? Reframing Fitness in a Changing Environment

Abstract

Fitness – the propensity to survive and reproduce in a particular environment – is a function of different environments and genotypes. Fitness incorporates the notion of probability, but in fisheries management questions about hatcheries, these probabilities are rarely presented or discussed. This contributes to lack of transparency and confusion between the potential biological effects of artificial propagation and policy positions about the level of acceptable risk. Here we present a knowledge-based, Bayesian assessment tool that describes overall and disaggregated probabilities of loss of fitness from three different mechanisms associated with different salmon hatchery scenarios: antagonistic selection in hatchery and wild environments, relaxation of selection from the wild, and effects of small population size. Hatchery scenarios were based on an extensive review of anadromous hatchery programs in the Pacific Northwest and range from highly intensive intervention in salmonid life-cycles, such as captive breeding programs, to those where there is little intervention. We compare these results with examples of habitat change on fitness driven by society’s needs for development and transportation. We conclude by describing a framework for integrating management decisions about the potential effects of habitat change and hatchery production on fitness that is necessary for salmon recovery