Reproductive traits, relative growth and maturity of blue crabs Callinectes danae and Callinectes ornatus in South Atlantic waters

The reproductive strategies of species play a fundamental role in formulating effective management plans and maintaining local community structure and ecological balance. This study investigated the reproductive characteristics of two sympatric species, Callinectes danae and Callinectes ornatus, in Atlantic waters. Monthly sampling was conducted from July/12 to June/14 in the coastal (sites: S1, S2, S3 and S4) and estuarine-lagoon (sites: S5, S6 and S7) areas of Cananéia-Iguape, Brazil. Significant differences in allometric coefficients were observed, particularly in the relationships chelipod length vs. carapace width (CW) for males and abdominal width vs. carapace width (CW) for females. Morphological sexual maturity was estimated at 58.8 mm CW for C. danae males, 54.5 mm CW for females, 45.0 mm CW for C. ornatus males, and 41.2 mm CW for females. Gonadal sexual maturity sizes were identified at 69.4 mm CW for C. danae males, 61.4 mm CW for females, and 58.4 mm CW for C. ornatus males, 46.9 mm CW for females. Both species spawn predominantly during the austral summer, with higher prevalence in site S5 for C. danae and S1 for C. ornatus. Recruitment occurred in austral spring and summer, with C. danae concentrated in estuarine-lagoon regions and C. ornatus along the coast. Reproductive patterns of C. danae were associated with temperature and salinity, while C. ornatus exhibited correlations with temperature and organic matter. This study highlights the influence of environmental factors on species' life cycles. Furthermore, it contributes to the evaluation of management and monitoring strategies, recognizing the economic and ecological significance of these species for sustaining these ecosystems.