The effect of temperature on release mortality of declawed <I>Menippe mercenaria</I> in the Florida stone crab fishery

Abstract

The stone crab, Menippe mercenaria (Say, 1818), fishery off Florida removes claws and releases the crabs to regenerate new claws and potentially re-enter the fishery. An in situ catch-and-release study was conducted during the 2011–2012 fishing season to refine estimates of release mortality. In this study, mortality estimates accounted only for mortality the crab incurred while in a holding pen, which excluded possible predation. The mortality estimates can be considered the minimum mortality that may occur from declawing. Across all samples, 12.8% of crabs died when no claws were removed, 40.8% when one claw was removed, and 62.9% when both claws were removed. Break type, temperature, and number of claws removed were significant variables in a generalized linear mixed model with random effects for region and station. The odds of dying increased by a factor of 1.33 for each degree increase in temperature, of 2.29 when both claws were removed compared with one claw removed, and 6.10 when a break was proximal of the basiischium (BI) compared with a break along the BI. Temperature ranged from 12.2 to 28.1 °C during the study, however, the predicted mortality across all treatments suggests release mortality may increase with climate induced warming of sea temperatures. The temperature effect observed suggests that release mortality rates are high throughout the fishing season in the southern region (>60% of landings) and early and late in the season in the central and northern regions when waters were warm (>20 °C).