A Spatio-Temporal Stock Assessment Model for Snow Crab in Eastern Canadian Waters

Fish stock sizes decline throughout the fishing season as fishery catches increase and this pattern can sometimes be used to estimate stock size based on the rate of decline in a catch per unit effort (CPUE) time-series. However, a key assumption of such approaches is uniform distribution of fishing effort, as apparent declines can also be affected by changes in the spatial distribution of the fishing fleet. We propose a spatio-temporal depletion model that adjusts for bias caused by changes in the fleet’s spatial distribution. This model is applied to geo-referenced catch and effort data from the economically important snow crab fisheries in eastern Canadian waters to improve parameter estimation.  Various model configurations are compared to assess the robust of the approach.