Reproductive Biology of the Invasive Blue Crab Callinectes Sapidus (Rathbun, 1896) on the African Atlantic Coast

The invasive blue crab Callinectes sapidus was monitored in the Moulay Bousselham Lagoon on the Moroccan Atlantic coast, from January to December 2023. This pioneering study on the African Atlantic coast aimed to evaluate the species' biometric characteristics, reproductive patterns, and spatiotemporal dynamics. Overall, 1932 crabs were collected from which 1806 were investigated. The average carapace width was 83.68 +/- 37.88 mm, carapace length was 38.38 +/- 15.25 mm, and average weight was 64.43 +/- 57.93 g. Significant sexual dimorphism was noted, with females larger than males, having an average carapace width of 89.82 +/- 36.72 mm and total weight of 66.82 +/- 50.87 g compared to males' 75.84 +/- 37.15 mm and 36.65 +/- 16.26 g, respectively. The carapace width at 50% maturity was 90.7 mm overall, with females maturing at a larger size (93.7 mm) compared to males (86.9 mm). The global sex ratio was skewed towards females (0.64:1), deviating significantly from the expected 1:1 ratio. Spatiotemporal variations revealed low abundance in winter, moderate in spring, and high in summer. Reproductive activity showed two peaks: spring (April) and summer (August), with increased gonadosomatic index and higher percentage of ovigerous females during these periods. These results confirm the typical reproductive dynamics of the species and highlight the characteristics of the invasive blue crab population in the Moulay Bousselham Lagoon, including smaller biometric traits and earlier maturity compared to other areas. Moreover, they emphasize the need for management strategies tailored to the local biological cycle and continuous monitoring to adapt to the crab's reproductive dynamics.