The Consequences of Claw Removal on Stone Crabs Menippe spp. and the Ecological and Fishery Implications

Abstract

The practice of claw removal in the fishery for stone crab Menippe spp. can affect fished populations in an atypical way because harvested individuals are not necessarily killed. In all stone crab fisheries, crabs are returned to the water after their claws are harvested with the expectation that claws may be regenerated, thus “renewing” the fishery. The number of legal-sized claws that can be removed from an individual differs (with local regulations) throughout the stone crabs' range. We examined the direct and indirect consequences of removing one and two claws by monitoring mortality and prey consumption in the short term (14 d) and mortality and growth over the long term (11 months). Claw removal induced mortality within days when wound widths were greater than 7 mm, regardless of the number of claws removed. Wound widths created by autotomy were similar to those created by a clean, forced break along the natural fracture plane. These results suggest that direct mortality following claw removal may be low in a two-claw fishery for stone crabs that do not incur large wounds; however, indirect effects that result from altered feeding abilities may be substantial. Stone crabs with one claw removed (the crusher) consumed fewer bivalves than control (intact) crabs, whereas stone crabs with two claws removed did not consume any bivalves but ate fish flesh. Consequently, bivalves, an important prey resource throughout the stone crabs' geographical range, are eliminated from a clawless crab's diet until its claws are regenerated. No stone crabs regenerated a legal-sized claw on the first molt after claw removal, and no stone crabs larger than 104 mm carapace width molted within 11 months. Thus, the long intermolt duration of legal-sized stone crabs and the reduced prey consumption for stone crabs that lost claws indicate that the return to the fishery of previously harvested stone crabs is probably an uncommon occurrence.

Received December 17, 2014; accepted June 15, 2015

ACKNOWLEDGMENTS

We would like to thank F. Dockery, J. Heinsohn, B. McCord, N. Moskos, M. Moreau, K. Brenkert, K. Anweiler, M. Perkinson, J. Yost, M. McAskill, L. Haselden, A. Spyropoulos, D. Spyropoulos, and volunteers for their support with field and laboratory work. Special thanks to M. Hughes, D. Whitaker, and J. Leffler for their assistance with experimental design, analyses, and manuscript review and to S. Brew, P. Meier, and C. Plante for logistic support. The comments of three reviewers improved this manuscript. Funding for this project was provided by the South Carolina Department of Natural Resources Commercial Saltwater License Revenue Fund and the Lerner-Grey Memorial Fund of the American Museum of Natural History. This publication represents the South Carolina Department of Natural Resources Marine Resources Research Institute contribution 739 and the College of Charleston Grice Marine Laboratory contribution 444.