Seasonal movement patterns of Jonah and Atlantic rock crabs along the U.S. Atlantic coast during 1992–2007

ABSTRACT Objective The Jonah crab Cancer borealis and Atlantic rock crab C. irroratus were traditionally bycatch species in the American lobster Homarus americanus fishery, but their economic importance has increased greatly in the United States since the 1980s. However, these species are data limited, and seasonal movements are poorly understood. Our objectives were to determine the seasonal distributions for both crab species and whether distributions differed by sex and maturity to improve understanding of habitat use and movement patterns. Methods Data were obtained from offshore bottom trawl surveys conducted in spring, fall, and winter by the Northeast Fisheries Science Center during 1992–2007. We conducted ANOVAs to estimate differences in average depth (m) and distance from shore (km) among sex and maturity categories by species for Jonah and Atlantic rock crabs within the Georges Bank and Mid-Atlantic Bight regions. Results Jonah crabs were typically closer to shore and at shallower depths in the fall and spring and were farther from shore and in deeper depths during the winter. Atlantic rock crabs across all sex and maturity categories were observed farther offshore at deeper depths in the fall and closer to shore at shallower depths in the winter and spring. Sex and maturity also influenced seasonal distributions for both species. Conclusions This work provides a better understanding of potential migration patterns of Jonah and Atlantic rock crabs seasonally that could help in determining appropriate spatial scales for management and interpretation of survey indices.