ENHANCING OREOCHROMIS NILOTICUS STOCK ASSESSMENT IN THE NILE RIVER IN ASWAN, EGYPT, BY USING TROPFISHR FOR SUSTAINABLE FISHERIES MANAGEMENT

This study investigated that length-based stock assessment parameters and reproductive biology of Oreochromis niloticus in the River Nile (Aswan, Egypt) aimed to identify strategies for sustainable yield. The TropFishR package in R is used to visualize and assess the stock status of O. niloticus in this work. A total of 739 fish were analyzed, with males representing 75.2% and a male-to-female ratio of 1:0.33. The gonadosomatic index revealed two distinct spawning seasons : March-April and September. Growth parameters for the stock were L = 33.61 cm, K = 0.339/year, and = 2.85. Total mortality (Z) was calculated as 4.03 year, with natural mortality (M) at 0.586 year and fishing mortality (F) at 3.44 year, resulting in an exploitation rate (E) of 0.85. These results indicate that the stock is severely overfished, with an Fcurr/Fmax ratio of 1.9. It is recommended that fishing pressure be decreased and that strong, evidence-based management techniques be put forward that will support in the maintenance and restoration of spawning biomass.