Some Fisheries and Biological Aspects of the Crayfish Procambarus clarkii (Girard, 1852) in the River Nile, Egypt

Procambarus clarkii, as an invasive species, has proved to have an adverse impact on the Egyptian freshwater system, nevertheless, its fisheries could be one of many ecosystem services it can provide to society. This study aims to document the main fisheries characteristics of this species during 2014. Many fishing methods were found to capture P. clarkii including trammel nets (Estaquaza and extended nets), gill nets, and traps. About 70% of the individuals had carapace lengths between 39 and 52 mm and 95 % the individuals had a mean carapace length that exceeds the harvestable limit (35 mm). The length-weight relationship data of P. clarkii showed an allometric growth for weight more than for length (b > 3). The variations in male and female sex ratio with length classes showed that males of P. clarkii predominated all length classes except length classes 8 and 12 cm total length. The results of this study indicate that the crayfish grows considerably longer in the River Nile than it usually does in its original environment and that there is an assisted population, and high yields are expected when crayfish from the River Nile are to be utilized for commercial purposes.