ASSESSING BERING SEA SNOW CRAB POPULATIONS
This research develops a spatially structured method for assessing Bering Sea snow crab population and tests the ability of current methods to assess this spatially dynamic species.
Cody Szuwalski, University of Washington, School of Aquatic and Fishery Sciences
André Punt, University of Washington, School of Aquatic and Fishery Sciences
Anne Hollowed, NOAA, Northwest Fisheries Science Center
The Eastern Bering Sea snow crab is a commercially important stock that was declared overfished in 1991; reasons for the decline are still unclear. Its population is spatially structured by migration over its lifetime, but current stock assessments ignore this structure and lack key pieces of information required for effective management. An assessment model that takes account of the crabs’ movement patterns could better capture their population dynamics and improve management capacity. A Washington Sea Grant-supported fellow developed a spatially explicit assessment method that tracks the movements of male crabs among four quadrants of the Bering Sea.
There was insufficient data to verify the accuracy of the new assessment method’s estimates of movement, recruitment, fishing mortality, and other quantities used to manage the fishery. However, the method did support developing an operating model that could be used to test the ability of current methods to estimate trends in abundance and fishing pressure in a spatially structured population. This model test showed that it was necessary to know the share of a target sample the survey technique actually caught and counted in order to reliably capture the dynamics of the population.