Pribs Blues Muse: Pribilof Islands blue king crab (Paralithodes platypus) recruitment limitation as a potential bottleneck to rebuilding from overfished status
The Pribilof Islands blue king crab stock was closed to directed harvest in 1999 and declared overfished in 2002, and is the only overfished stock in the North Pacific. This fishery closure combined with habitat protection and bycatch reduction measures have failed to rebuild the stock. The 2015 Stock Assessment and Fishery Evaluation index of stock biomass was 8% of maximum sustainable yield (BMSY), with no indication of recruitment. We propose to investigate if larval supply, habitat availability, or predation on juveniles are limiting recruitment to inform potential future rebuilding efforts. Our field study in the Pribilof Islands will examine these three potential causes of recruitment limitation. Larval collectors and dive surveys will quantify abundance and distribution of newly settled and juvenile king crabs in nearshore habitats to test the role of larval supply. Dive surveys and drop cameras will characterize habitat in nearshore areas, which will be compared to historical data to identify any changes over time in habitat availability. Dive surveys, fish stomach contents and in situ tethering experiments will quantify predation pressure. This multifaceted approach will address the mechanisms controlling the abundance of early benthic phase Pribilof Islands blue king crabs and evaluate whether lack of juvenile recruitment is occurring and limiting recovery in the fishery. While we plan to focus on blue king crab, we will collect information on any red king crab encountered in the study as well. The results of this study will thus be applicable for management of Bering Sea blue and red king crab stocks by providing baseline data regarding crab recruitment, habitat and predation. Our proposed empirical studies specifically address NPRB research priorities on data poor and depressed stocks and will be a significant contribution to understanding the processes controlling crab recruitment dynamics.
Start Date: 2016-08-31
End Date: 2019-02-27
NOAA–AFSC Shellfish Lab