GROWTH, MATURITY AND MORTALITY OF THE BLUE CRAB CALLINECTES ARCUATUS ORDWAY, 1863 (DECAPODA, PORTUNIDAE) IN A MEXICAN COASTAL LAGOON

In Mexico, swimming crabs are considered a strategic resource because it supports artisanal fishing when the main fish resource (shrimp) is in closed season. In "Marismas Nacionales" the blue crab fishery is relatively new, and the catches have been maintained due to the national demand and the availability of the resource. Individual growth, sexual maturity, sexual ratio and mortality were estimated for Callinectes arcuatus for providing information about its population dynamics. Samplings were carried out every 10 days from October 2002 to November 2003. A total of 6022 specimens of C. arcuatus were collected (70.05% were males and 29.95% females) with a maximum carapace width (CW) of 138.5 mm in males and 118.7 mm for females. For males, case 5 of the Schnute model was the best model for describing the individual growth (k = 0.97 year(-1) and s = 196 mm), while case 2 (k = 3.11 year(-1) and s = 121.6 mm) was a better fit for females. The size at sexual maturity was 88.9 mm CW in males (CI = 88-90 mm) and 82.2 mm CW in females (CI = 81.7-82.9 mm). The estimated age at sexual maturity was 0.79 and 0.91 years for males and females, respectively. The male/female sex ratio was 1 : 0.43, significantly different (p <0.001, X-2 = 969) from the theoretical sexual ratio (1 : 1). Mortality rates in males were M = 1.63, Z = 2.43 and F = 0.80, and in females they were M = 1.46, Z = 2.56 and F = 1.10. The exploitation rate indicated the resource is below the optimum level of exploitation and the maximum yield per recruit.