POPULATION DYNAMICS AND EXPLOITATION PARAMETERS OF CALLINECTES AMNICOLA (ROCHEBRUNE, 1883) IN THE LAGOON COMPLEXES OF SOUTH BENIN, WEST AFRICA

Abstract

To ensure the sustainable management of fisheries resources in Benin, the population dynamics of Callinectes amnicola are being studied in two locations: the lake Nokoué-Porto-Novo lagoon complex and the lake Ahémé-Coastal lagoon complex. Monthly recordings of carapace length were conducted on 5,850 crabs from lake Nokoué-Porto-Novo lagoon complex between February 2017 and January 2018, while 2,252 crabs from lake Ahémé-Coastal lagoon complex were analyzed using FiSAT II software to determine population dynamics parameters. The estimated asymptotic carapace lengths (L∞) were found to be 14.70 cm and 17.85 cm for lake Nokoué-Porto-Novo lagoon complex and lake Ahémé-Coastal lagoon complex, respectively. The growth rate (K) was calculated as 3.1 for lake Nokoué-Porto-Novo lagoon complex and 0.63 for lake Ahémé-Coastal lagoon complex. Estimates of fishing mortality (F) were determined as 6.97 year−1 for lake Nokoué-PortoNovo lagoon complex and 0.66 year−1 for lake Ahémé-Coastal lagoon complex. The size at first capture was estimated to be 11.87 cm for lake Nokoué-Porto-Novo lagoon complex and 11.20 cm for lake Ahémé-Coastal lagoon complex. The current exploitation rates were found to be 0.60 for lake Nokoué-Porto-Novo lagoon complex and 0.3 for lake Ahémé-Coastal lagoon complex. These findings indicate that the stock of Callinectes amnicola is overexploited in lake Nokoué-Porto-Novo lagoon complex, while in contrast, it is not overexploited in lake Ahémé-Coastal lagoon complex. The stocks in lake Nokoué-PortoNovo lagoon complex have reached a critical level of overexploitation. Therefore, it is necessary to reduce the level of species exploitation in this complex while respecting the optimal carapace length.