~ 195 ~ International Journal of Fisheries and Aquatic Studies 2018; 6(1): 195-201 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 (GIF) Impact Factor: 0.549 IJFAS 2018; 6(1): 195-201 © 2018 IJFAS www.fisheriesjournal.com Received: 16-11-2017 Accepted: 18-12-2017 Appolinaire Goussanou University of Abomey–Calavi, Polytechnic School of Abomey- Calavi, Department of Animal Production and Health, Laboratory of Animal Biotechnology and Meat Technology, 01 BP 2009, Benin Gabriel Assouan Bonou University of Abomey–Calavi, Polytechnic School of Abomey- Calavi, Department of Animal Production and Health, Laboratory of Animal Biotechnology and Meat Technology, 01 BP 2009, Benin Antoine Chikou University of Abomey–Calavi, Faculty of Agronomic Sciences, Laboratory of Hydrobiology and Aquaculture, 01 BP 526 Cotonou, Benin Guy Apollinaire Mensah Agricultural Research Center of Agonkamey, National Institute of Agricultural Research of Benin, 01 BP 884, Cotonou, Benin Issaka Youssao Abdou Karim University of Abomey–Calavi, Polytechnic School of Abomey- Calavi, Department of Animal Production and Health, Laboratory of Animal Biotechnology and Meat Technology, 01 BP 2009, Benin Correspondence Appolinaire Goussanou University of Abomey–Calavi, Polytechnic School of Abomey- Calavi, Department of Animal Production and Health, Laboratory of Animal Biotechnology and Meat Technology, 01 BP 2009, Benin Sizes at first sexual maturity and capture and demographic parameters of crabs Callinectes amnicola and Cardisoma armatum in the complex Nokoué Lake Porto-Novo lagoon in South Benin Appolinaire Goussanou, Gabriel Assouan Bonou, Antoine Chikou, Guy Apollinaire Mensah and Issaka Youssao Abdou Karim Abstract Crabs Callinectes amnicola and Cardisoma armatum are intensively exploited in the complex Nokoué lake Porto-lagoon in South Benin. This study aims to evaluate the current exploitation level of these species based on the sizes at first sexual maturity and capture as well as on certain demographic parameters. For this, 1287 Callinectes amnicola crabs and 322 Cardisoma armatum crabs were collected, sexed and measured between May 2016 and April 2017. The study revealed that in both crab species, the calculated sex ratios were not different from the theoretical sex ratio (p> 0.05). In crab Callinectes amnicola, the size at first sexual maturity of females was lower than that of males whereas in Cardisoma armatum, males had a size at first sexual maturity inferior to females. The size at the first capture of Callinectes amnicola crab (4.60 cm) was greater than that of the Cardisoma armatum crab (4.41 cm). In both crab species, first-catch sizes were all smaller than first maturity sizes. The growth coefficient and the growth performance index in the crab Cardisoma armatum were superior to those of the crab Callinectes amnicola. The total mortality, natural mortality, and fishing mortality were higher in crab Cardisoma armatum than in crab Callinectes amnicola. In the complex Nokoué lake Porto-Novo lagoon in South Benin, crabs Callinectes amnicola and Cardisoma armatum are overexploited. Keywords: sexual maturity, growth, mortality, exploitation, Benin 1. Introduction In Benin, fishing is the main source of animal protein. This activity supplies nearly 86% of the country's fish production [1, 2] . In recent years, as a result of rapid population growth, the demand for fish and fish products has considerably increased. This situation has led to an overexploitation of aquatic resources, placing fish and crustacean stocks under high fishing pressure [3, 4] . In Benin’s aquatic environments, as fishes and shrimps, crabs are an important source of protein and a fundamental component of culinary recipes in Benin [5] . In the fisheries of South Benin, particularly the Ahémé lake and the complex Nokoué lake Porto-Novo lagoon, which represent the two main fishing sectors [6, 7, 8] , the exploitation of these species is intensifying from day to day and significant quantities are daily landed [5] . In order to conserve and rationally manage the stock of this resource, biological and demographic studies of the population of these species are needed. Among the important main features to the implementation of fisheries management programs, the knowledge of the onset sexual maturity and captures sizes occupies a choice place [4] . This approach is of a particular interest in order to evaluate the exploitation level and to determine the minimum sizes of catch and to regulate the meshes of fishing nets. Contrary to the fish species which have been the subject of many bioecological studies in aquatic environments [4, 9, 10, 11, 12] , work on the onset sexual maturity and capture sizes of the crab population is fragmentary. Indeed, studies and knowledge of crab species in aquatic environments in Benin are at their beginning. However, some works have been done on these species and mainly concerned their diversity [6] , their exploitation and the different marketing channels [7, 8] and finally their domestication [5, 13] . The main objective of this work is to improve the scientific knowledge of the ecology and exploitation of crabs Callinectes