Temporal Changes in Spatial Distribution of Bristol Bay Red King Crab in the Eastern Bering Sea and Their Implications for Fisheries Management

Annual summer trawl survey data show that spatial distributions of Bristol Bay red king crab, Paralithodes camtschaticus, changed greatly over time. Large mature female red king crab (≥105 mm carapace length) primarily occurred in southwestern Bristol Bay before 1977, and their distributions shifted to central and northeastern Bristol Bay in the late 1970s and early 1980s. Mature female red king crab have been found primarily in central Bristol Bay since the early 1980s. The distribution centers of large mature females moved south slightly during 1988–1990, 1999-2000, 2009 and 2012-2013, but did not reach the southernmost locations previously occupied in the 1970s. Northward shifts in spatial distribution of mature females appear to be associated with warmer bottom water temperatures and may partly explain recruitment variability. Northward shifts in larval hatching locations make it difficult to supply larvae to the southern portions of their range, as an increased proportion of larvae hatched in central Bristol Bay are likely carried beyond the northern limits of juvenile nursery areas. These northward spatial shifts are associated with declines in productivity resulting in lower recruitment, subsequent low spawning biomasses, and reduced total allowable catches.