Life History Parameters and Stock Status of the Kawakawa, Euthynnus affinis (Cantor, 1849) from the Gulf of Aqaba, Red Sea, Egypt

The  kawakawa Euthynnus affinis, is a highly commercial tuna species in the Red Sea. To assess the  species’ fishery status, the life history and population dynamic parameters have to be identified. A total of 615 length measurement data were randomly collected during the period from February 2021 to May 2023 from the Gulf of Aqaba, Red Sea, Egypt. Life history  characteristics comprising age and growth, mortality, and utilization rate were evaluated based on the length frequency analysis. The average total length was 55.32±6.53 cm for males and 54.95±6.50 cm for females. The "b" values in length-weight relationship were estimated at 2.981 and 2.962 for males and females respectively which designated that E. affinis grows isometrically. The  combined sexes’ growth parameters were computed for as  L∞= 83.64 cm,  K= 0.47 year^-1 and  t₀₌ -0.22 year. Total mortality, natural mortality and fishing mortality were valued at 1.413, 0.77 and 0.643 year^-1 respectively, with an exploitation rate of 0.455. The  biological reference points F_opt and F_limit were calculated at 0.39 and 0.51 year^-1 respectively. The results revealed a good situation for E. affinis stock in the Gulf of Aqaba, since the majority of captured kawakawa had achieved its maturation as indicated by Lc > Lm. The results demonstrating that E. affinis fishery in the Gulf of Aqaba, Egypt has a potential for development nevertheless any recommendations should be consider the  tuna species’ migratory behavior and the multi-species nature of Gulf of Aqaba fisheries in Egypt. Furthermore, for  the species’ sustainable management, there is a need for continuous monitoring of fishing effort and improve fishery data gathering.