Sexual Maturity Scale of the Swimming Crab Callinectes pallidus (Rochebrune, 1883) from Lake Nokoué in South Benin, West Africa

Aims: Reproductive parameters are important tools for the sustainable management of halieutic species in the water bodies of its exploitation. This study intends to characterize the sexual maturity scale of swimming crab Callinectes pallidus, perform testicular and ovarian structures in order to develop a specific maturity scale.

Study Design: This study was carried out with macroscopic and microscopic observations of 394 specimens of crabs including 206 females and 188 males.

Place and Duration of Study: The specimens used in this study were collected monthly from March to July 2018 from small scale fisheries of Lake Nokoué (Benin).

Methodology: At the laboratory, each crab specimen is identified and its sex determined. Grids for describing each sexual maturity stage of the crab C. pallidus were developed based on the Zairon et al. (2015) scale. Histological sections of female and male gonads were analyzed in order to certify the different stages of sexual development noted from the macroscopic study.

Results: Macroscopic analysis of external and internal anatomy and histological study of male and female gonads of C. pallidus allowed to establish a sexual maturity scale with 5 stages in females and 4 stages in males respectively. Macroscopic observations made with a binocular magnifying glass allowed to describe the characteristic features of the sexual development cycle of the species. The histological study confirmed the results of the macroscopic analysis. Significant difference was recorded between the mean oocytes diameters of the different oocyte development stages (p<0.05).

Conclusion: The outcomes of this constitute an important database for the assessment of the reproductive parameters of the species in the water bodies of its exploitation. The stages IV and V are the mature steps in the female development whereas the stages III and IV are that of the male. It is recommended to allow C. pallidus reach the sexual maturity size (5,95 cm for female and 6,38 cm for male) before their exploitation to ensure the sustainable management of the species.