Fisheries Discard Mortality: Data Gaps and Solutions

Recreational and commercial fisheries experience continued restrictions due to high levels of fishing mortality and slow stock rebuilding.  Moreover, discard of bycaught fish occurs in almost all fisheries, and stakeholders have sought solutions to barotrauma and discard mortality problems.  Managers and scientists face data gaps in determining how discard mortality rates affect stock status and fishing levels.  In 2013, NMFS began to develop a paper to review discard mortality initiatives, identify and prioritize data gaps, and identify components of a national discard mortality science strategy.  In 2012 and 2013, NMFS’ Bycatch Reduction Engineering Program (BREP) funded over $1.2 million in research designed to reduce discard mortality.  A 2012 BREP project conducted a field validation study to evaluate the Reflex Action Mortality Predictor (RAMP) approach for determining discard mortality rates of Dungeness crab (Metacarcinus magister) in Oregon fisheries. This project evaluated the accuracy of RAMP, which relates reflex impairment to probability of mortality, given that the methodology typically involves short-term holding of animals in unnatural conditions (ex-situ tanks). Through this study and a discussion of NMFS’ BREP and Bycatch Program, we present information on data gaps and progress made in mitigating fisheries discard mortality.