Population structure of Sardinella gibbosa (Bleeker, 1849) with special reference to spawning ground in the Gulf of Suez, Egypt

Identifying the population and reproductive structure of Sardinella gibbosa in the Suez Gulf is the main objective of the current study. About786 specimens of S. gibbosa were collected from purse seine catch in the Suez Bay with a range of 4.6 to 18.1cm for total length; where the highest frequency was observed for length group 12 cm. The length-weight relationship showed an isometric growth pattern (b=3.01). Three life spans were confirmed from otolith reading with a rapid length increasement during the first one. Sex ratio was 1.0:1.75 for males and females respectively (X², P < 0.05). Gonadosomatic index revealed that S. gibbosa spawns once during winter. Length at first sexual maturity was 13.0 and 13.2 cm for male and female respectively, in addition to 11.3 cm for length at first capture (Lc₅₀)_, revealed the occurrence of overfishing. Total mortality (Z) was 2.75; natural (M) and fishing (F) mortality were 1.06 and 1.69 respectively. Comparing the value of fishing mortality with biological reference points (F _Optimum = 0.53 year⁻¹ and F _Limit = 0.69 year⁻¹) in addition to 0.62 for exploitation rate; confirmed the occurrence of overexploitation. The Gulf of Suez was found to be a confirmed spawning and rearing ground for S. gibbosa. As a result of overexploitation, some modifications in size selectivity of fishing gear are required and reduction of fishing effort is a goal to be achieved.