Search for: All records

In southern New England, rapid ocean warming over the past two decades has caused substantial redistributions of fishes, invertebrates, and the fisheries they support. The rapid emergence of the warm water-tolerant Jonah crab (Cancer borealis) fishery, once discarded as bycatch from the now declining lobster fishery, illustrates a prime example of climate-adaptive shifts in southern New England fisheries. However, limited data exist on the basic life history of Jonah crabs, despite their growing economic and societal value. This hinders ocean management capacity to meet multiple ecological, economic, and socio-cultural goals of sustainable harvest. Off the southern coast of Rhode Island, Jonah crabs are currently harvested in two fishery zones (inshore and offshore) delineated as holdovers from the lobster management zones. Jonah crabs landed in the offshore fishing zone are significantly larger, on average, than those landed in the inshore fishing zone. This presentation gives an overview of a study developed to test the hypothesis that these size differences reflect ontogenetic migration of Jonah crabs from the inshore to offshore fishing zones. To do this, we developed seasonally resolved isoscapes (isotope maps) of the region, which revealed distinct geospatial gradients in environmental stable isotope values between inshore and offshore necessary to track potential movement of Jonah crabs between fishing zones. We then used stable isotope analysis of three Jonah crab tissues with differential metabolic turnover times: the carapace (reflecting residence one year ago), muscle (reflecting residence averaged over the last ~4 months), and hepatopancreas (reflecting residence averaged over the last ~4 weeks) to construct an “isotopic clock” of residence throughout the regional isoscapes. This work provides key data on critical life history characteristics of the Jonah crab through a collaborative effort by scientists at the University of Rhode Island and the Rhode Island Department of Environmental Management to inform management decisions on this emerging climate-adaptive fishery.