Size at Maturity, Shell Conditions, and Morphometric Relationships of Male and Female Jonah Crabs in the Middle Atlantic Bight

Abstract

The Jonah crab Cancer borealis is a data-poor species with an unknown stock status. They were historically caught as bycatch in American lobster Homarus americanus traps. The decline of the southern New England lobster stock since 1990 helped stimulate a targeted fishery and a sixfold increase in both the landings and ex-vessel value of Jonah crab. Current knowledge on Jonah crab growth and reproduction is scarce and dated. Therefore, this research focused on updating fundamental biological information for Jonah crabs in the Middle Atlantic Bight. Morphometric analyses determined that male crabs reach size at 50% sexual maturity (SM50) at 98.3 ± 1.4 mm carapace width (CW; ±95% CI), and female crabs reach SM50 at 88.2 mm CW. These values are below the current minimum legal size. An increase in the proportion of female crabs in a new-shell condition during the spring and summer months suggests a seasonal mating period. Expanding available information will substantiate accurate appointment of minimum legal sizes, minimize discard mortality, and increase understanding of stock dynamics, thus improving management and long-term sustainability for the Jonah crab fishery.