Kate Richerson1
1NOAA
October 17th, 2017 9:00 (PST): FSH 203
Reconstructing the historical abundance of West Coast Dungeness crab (Cancer magister) using catch data
US Dungeness crab (Cancer magister) landings are valued at >$200 million annually, making it one of the most economically-important West Coast fisheries. The fishery has been managed by the states under a simple “3-S rule” (referring to size, sex, and season) since the 1940s. No stock assessment is performed, but the conventional wisdom suggests that the vast majority of legal-sized crabs are taken every season. We use catch data in the form of fish tickets and some limited logbook data in combination with depletion estimators to estimate the pre-season abundance of legal-sized crabs from 1982-2015. This work is still in progress, but results so far indicate that most legal crabs are indeed taken each season, but that populations are stable or increasing. We find evidence for density-dependent catchability, and suggest that failing to account for this can bias abundance estimates downward.