The ecological effects of claw removal on stone crab (Menippe mercenaria) and habitat-related phenotypic variation
Duermit, Elizabeth A.
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The stone crab (<i>Menippe</i> spp.) fishery practice of claw removal can affect fished populations in an atypical way because harvested individuals are not necessarily killed. 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. Laboratory and mark-recapture studies were conducted to examine the ecological effects of one- and two-claw removal. In the laboratory, direct mortality resulted from claw removal when wounds were large and prey accessibility decreased for crabs that survived claw removal. Two claw removal crabs were motivated to feed but unable to consume bivalves, an important prey resource. In the field, claw removal affected probability of recapture, time at large, direction moved (particularly for males), and dispersal distances. Decreased mobility following claw removal could further limit prey availability and clawless crabs may be more susceptible to predation. These negative indirect impacts may underlie the low incidence of fishery-related regenerated claws in the population (2.5–13.5%). Stone crabs in two adjacent rivers collected in a year-round trapping study exhibited habitat partitioning, with significantly more brown (compared to spotted) crabs, a higher proportion of males, and larger crabs collected adjacent to expansive intertidal oyster reef habitat. Brown coloration for stone crabs on oyster reefs may confer a fitness advantage if these crabs are more cryptic than spotted crabs. These results greatly improve our knowledge related to the stone crab fishery as well as stone crab demographics in an area within the South Atlantic Bight.