Reduction of bycatch mortality for non-target crab species in the commercial snow crab (Chionoecetes opilio) fishery

Crab fisheries in Alaska use baited pots to capture crab and bring them to the surface. Only males of
a minimum size can be retained while females, smaller males, and crab from non-targeted species must be returned
to the sea. The process of sorting and discarding non-retained crab results in bycatch mortality of unknown magnitude,
under some conditions estimated to be up to 100%. Recent regulations recognize the importance of considering all sources
of fishing mortality, mandating that bycatch mortality must be considered when setting catch limits. Currently a rate
of 50% mortality is applied to the crab discarded from pot fisheries in Alaska, but it is widely acknowledged further
work is needed on both refining this estimate and reducing discarded crab losses. We used an index of crab reflexes
recorded during the commercial snow crab fishery to investigate the predicted discard mortality rate. The method known
as Reflex Action Mortality Predictor (RAMP) has been developed for both fish and invertebrates. Rates from 22 commercial
vessels were found to be generally low, averaging 5.9% although rates climbed significantly when windchill temperatures
at the sorting table were below -10 degrees C. Low numbers of observations at the lowest temperatures and lack of
observations during comparable windchill exposures confounded the analysis. These datasets were archived as part of the North Pacific Research Board legacy project recovery effort undertaken by Axiom Data Science and NPRB in 2025. The goal of the recovery effort was to assess the NPRB-funded data projects from 2002 to 2014 and archive final data packages that were ready for publication to increase long-term accessibility and discoverability. Data packages were archived as is given limited funding and resources.