Distribution of juvenile crabs of genus Callinectes in the estuary-lagoon system of Laguna, Santa Catarina State, Brazil

Abstract

Crabs of genus Callinectes represent one of the most exploited resources by the artisanal fisheries in the Laguna estuary, Santa Catarina, Brazil. Juveniles of three species coexist simpactrically in shallow waters of the estuarine-lagoon system. This paper studies the distributions in space and time of the relative abundance and size (carapace width - CW) of juvenile Callinectes spp. over 12 months. From April, 1994 to March, 1995, 4,450 individuals were caught, and C. danae represented 64.3% of the catch, whereas C. sapidus, the second most abundant species accounted for 35.6% of the abundance. Only four specimens of C. bocourti were identified in the samples. Two-way ANOVA indicated that the factors season and area of collection influenced in the variation of species abundance individually, and interactions were non significant. C. danae was most abundant during summer and fall, and C. sapidus during spring and summer. Both species were least abundant in the winter. Peak abundance occurring at different times of the year for each species suggests a life history strategy to minimize competition for nearly the same resources (habitat, food). The arrival of recruits of C. danae occurs in the summer, and growth through spring is evidenced by shifts in the size frequency distribution. For C. sapidus this pattern is not evident since smaller size individuals were caught throughout the year. Both species showed a high frequency in the size range 27.5 - 37.5 mm CW individuals in areas B and C where average salinity ranges between 10 and 15%o, suggesting that their eurihaline environment shows preferential characteristics for the development of the juveniles and where potentially niche overlap between species would occur.