Challenges in Determining Release Mortality Rates for Use in Pacific Salmon Management

Fisheries managers use release mortality rates for planning the impacts of fisheries on target and non-target species. Researchers also use release mortality rates to evaluate the efficacy of mitigation strategies designed to improve survival and fitness. The proliferation of capture and release research using tagging, holding, or physiological tools offers an opportunity to provide better context specific advice (e.g. water temperature, gear, spatial location, fish condition) that can drive species-specific differences in release mortality rates for Pacific salmon. The challenges in applying this research include dealing with the additional stress that the experimenter has imposed (e.g. handling, confinement stress, transportation effects, tagging impacts, recovery methods), estimating natural mortality, and coping with increasing amounts of research, especially conflicting evidence. In order to provide science advice on release mortality rates to fisheries managers, an evaluation process that focuses on understanding the role of multiple factors in explaining the relative differences among disparate studies is required. In addition, a method for assimilating current and future research into species-specific release mortality estimates for each fishery (i.e. by gear and location) is desired in management planning.