Abundance and catchability estimates of the Atlantic blue crab Callinectes sapidus based on mark-recapture data from the northern Yucatan Peninsula

A short-term Jolly-Seber mark-recapture model experiment is described. This experiment was aimed at estimating the rate of catch per unit effort (CPUE) and the catchability coefficient (q) of the Atlantic blue crab (Callinectes sapidus) in the fishing port of Sisal, Yucatan, Mexico. To estimate the local population size, 52 traps were deployed along four transects located in a coastal capture area of 3600 m(-2). The CPUE and q were compared between the daily mark-recapture Jolly-Seber experiment and the bi-monthly (carried out every 2 months) samplings. The average abundance was estimated at 3475 individuals. All three suggested scenarios, applied to estimate densities, gave similar estimates, i.e. 0.0386, 0.0350, 0.0365 crabs m(-2) for the first (Previously Cited Attraction Radius), second (CPUE per transect) and third (Catchability-Density Relationship), respectively. Based on the latter scenario, densities ranged from 27,900 (annual average) to 36,500 (Spring) crabs km(-2). The average CPUE of the daily mark-recapture experiment was estimated at 1.96 crabs trap(-1), whereas the average bi-monthly CPUE was estimated at 1.13 crabs trap(-1). The q (per trap) was estimated at 0.0186 for the daily mark-recapture experiment and at 0.0247 for the bi-monthly sampling. Both catchability and CPUE increased in individuals whose size ranged between 110 and 170 mm CW. However, no significant difference (ANCOVAs) was found between the daily and bi-monthly samplings neither in CPUE nor in catchability. The use of both mark-recapture data and the Jolly-Seber model proved to be a fast and reliable method for estimating the abundance and catchability of Atlantic blue crab.