Red king crab larval advection in Bristol Bay: Implications for recruitment variability

Abstract

Recruitment variability is poorly understood for Bering Sea crab stocks. The nearshore area in southwest Bristol Bay (Alaska, USA) is hypothesized as having historically (i.e., prior to ~ 1980) been the most important spawning ground for Bristol Bay red king crab (Paralithodes camtschaticus) because post-larvae are thought to have been most likely to reach optimal settlement habitat along the Alaska Peninsula when hatched from this area as part of an endless-belt reproductive strategy. We coupled a biophysical and oceanographic circulation model to test this hypothesis, investigate larval connectivity of more recent female spatial distributions, and evaluate the importance of climate variability on larval advection trajectories. Predicted settlement success varied through changes in larval pelagic duration and oceanographic circulation patterns: Shorter advective distance was associated with warmer conditions, causing higher rates of local retention relative to cold conditions. Contrary to earlier models, most larvae hatched in southwest Bristol Bay were advected offshore away from good habitat, whereas larvae hatched in central and nearshore Bristol Bay were retained in or advected to good habitat along the Alaska Peninsula. Our results suggest contemporary spatial distributions can supply settlement-competent larvae to nurseries along the Alaska Peninsula and that under certain conditions, larvae may reach the Pribilof Islands when hatched from southwest Bristol Bay. Our study informs the role of environmental variability on larval transport and provides context within which to structure future investigations of recruitment mechanisms.