ENHANCING Oreochromis niloticus STOCK ASSESSMENT IN THE NILE RIVER IN ASWAN, EGYPT, BY USING OF TropFishR FOR SUSTAINABLE FISHERIES MANAGEMEN.

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 Ф = 2.85. Total mortality (Z) was calculated as 4.03 year⁻¹, with natural mortality (M) at 0.586 year⁻¹ and fishing mortality (F) at 3.44 year⁻¹, 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.