Abstract

Little is known about the growth of male stone crabs Menippe mercenaria in Florida waters. For the most part, information from laboratory and tagging data has not been analyzed thoroughly to obtain a growth curve for the species. In this paper, I synthesized existing and new methods to construct a growth curve from available data. Two components of growth were estimated in detail: the relationship between postmolt and premolt size and the relationship between intermolt period and premolt size. The first relationship was estimated from data from captive crabs by relating the sizes before and after ecdysis with a segmented regression model. The relationship between intermolt period and premolt size was estimated from data from laboratory studies in which crabs were allowed to molt once and the subsequent intermolt periods were recorded exactly. Because long exposure to laboratory conditions may affect growth rates, the molt–frequency relationship also was estimated with methods that require one of two types of information that can be gathered in a shorter period of time: the time to first molt in captivity or the proportion of crabs that molt after an observation time of arbitrary duration. The intermolt period–size relationship also was estimated from mark–recapture data from wild crabs that comprised individual records of initial size, time from release to recapture, and a binary variable that indicated whether or not each animal had molted. I then used simulation analysis to develop a growth curve for a hypothetical stone crab cohort; individual (stochastic) variability in the two components of growth was considered in the analysis. The simulation used growth increments predicted by the estimates from the laboratory data and molt frequencies predicted by the estimates from the tagging data. The results suggested that, on the average, male stone crabs are recruited into the fishery at age 2.25 years and can live to be at least 8 years old.

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