Crabs are an important biological component of the West African lagoon fauna and are exploited by fishing communities. This paper presents a synthesis of the current understanding pertaining to the diversity, biology and exploitation of these crabs in order to identify promising research paths for this zoological group. A literature review was done. Thirty-two species belonging to thirteen families and twenty-three genera have been indexed by previous investigators and we plan on making use of this information in defining future research direction. The biology of crabs has been the subject of much research focused on Callinectes amnicola (Rochebrune, 1883) species. C. amnicola is an omnivorous species whose males are known to mature between 63 and 105 mm shell width, while females mature between 83.5 and 116.2 mm shell width. Fertility varies from 0.47 to 4.8 million eggs per female. However, exploitation parameters for this species in various lagoons are not available. A research direction geared towards establishing a new and thorough inventory along with currently nonexistent but relevant exploitation parameters will go a long way in defining sustainable management measures for these crab species.

The Indo-Pacific portunid, Charybdis hellerii (A. Milne-Edwards, 1867), is a crab species native to the Indian and Western Pacific Oceans and has previously colonized the Eastern Mediterranean and the Western Atlantic. It is now recorded in the Eastern Atlantic, on the coast of Benin, where a thriving population has established. This invasive and widely distributed species exhibits morphological variations within and between populations, which are discussed in detail. Its current distribution is presented, and its future expansion along the West African coast and future impact on coastal ecosystems and local fisheries are the object of tentative forecasts. Illustrations of sexually mature specimens from different sizes and regions are presented, and their allometric, individual and geographical variations are discussed. A new synonymy and a new account on the taxonomy and the biology of the species are presented. Illustrations of the lectotype and the paralectotype of C. hellerii are also provided for the first time. Charybdis spinifera (Miers, 1884), C. merguiensis (De Man, 1887) and C. vannamei Ward, 1941 are here treated as subjective junior synonyms of C. hellerii. The holotype of C. spinifera and two syntypes of C. merguiensis are illustrated.

Aquaculture development in Benin depends heavily on small-scale and subsistence aquaculture producers (SSAPs), who are sustaining production activities. The aquaculture sector is vulnerable to market shocks because of its dependence on inputs and equipment, which are mainly imported from overseas. The recent outbreaks of global aquaculture diseases have also proven the sensitivity of the sector. The vulnerability of SSAPs is expected to increase as a subsequent result of the coronavirus disease 2019 (COVID-19) pandemic. This is the reason why COVID-19-related difficulties affecting aquaculture production deserve to be evaluated in the country's aquaculture sector.We conducted an online survey to assess the impact of COVID-19 and the resulting restrictive measures on the functioning of SSAPs farms. Data were collected from 98 SSAPs informants spread over the geographic area with high aquaculture production potential in the country. The rate of increase in input prices, linear discriminant and factorial correspondence analyses projected severe constraints in almost all the value chain. The rates of increase in the unit price of inputs increased from 14% to 188%, thus weakening aqua-farmers' purchasing capacity. COVID-19 has led to a drop in the sales turnover of aqua-farms, resulting in staff reductions and unemployment. Difficulties in accessing quality inputs have led to the disruption of fish growth and thus the production cycle. The sale of aquaculture products saw a 20%-30% drop in turnover in many farms. The critical challenges mentioned by both men and women SSAPs are mainly the high cost of fish feed, the rising input and transport costs, and the lack of financial resources. Therefore, short-, medium-, and long-term mitigation measures are suggested and could help to alleviate these difficulties while sustaining the blue revolution already under way. This community of men and women SSAPs should adoptThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

This study aimed to compare the growth performance and economic profitability of rearing Oreochromis niloticus in floating cages using three feeding strategies (5 days a week, 6 days a week, and 7 days a week) coupled with three stocking densities (20, 40, and 60 fish·m−3). Male monosex fish measuring 6.44 ± 0.18 cm and weighing 3.42 ± 0.7 g were used. The controls were weighed every 15 days from the 35th day of rearing until 185 days to assess zootechnical parameters. BioMar feed (Efico Cromis 832F) was used during the study, and the feed ration was adjusted for each treatment every 2 weeks. At the end of the study, the average weights varied from 293.09 g to 468.41 g for the conditions of 40 fish·m−3 with a 5/7-day diet and 20 fish·m−3 with a 7/7-day diet, respectively. The yield per m2 values were between 7.11 kg and 23.17 kg, respectively. On the other hand, the economic profitability was better with the condition of 40 fish.m−3 with daily feeding. These results suggest that in the Toho-Todougba lagoon complex, a stocking density between 40 and 60 fish·m−3 coupled with daily feeding (three times a day) promotes the optimization of fish production and profitability of fish farming.

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.