First Results of the Study on Reproductive Biology of the Frigate Tuna (Auxis thazard) in the North Atlantic of Morocco.

To investigate the reproductive behavior of the frigate tuna (Auxis thazard) along the North Atlantic coast of Morocco, a comprehensive study was conducted between February and October 2020. A total of 215 frigate tuna specimens, obtained from both artisanal fishery and commercial purseseiners, were meticulously examined on a monthly basis. The study focused on evaluating various reproductive parameters including sex ratio, condition factor (K), gonadosomatic index (GSI), and sexual maturity progression. The findings of this study revealed that the straight fork lengths of the frigate tuna ranged from 30 to 43cm. Analysis of the sex ratio indicated a slight dominance of females, with a ratio of 1.06 females to every male (observed sex ratio: 1:0.06; X² observed = 1.21, which was below the theoretical X² = 3.84 threshold at P< 0.05). The size at which individuals reached sexual maturity (FL 50) was estimated to be 36cm for females and 38cm for males. Through monthly assessments, it was observed that the variation in maturity stages, GSI, and K values suggested a spawning period predominantly occurring between June and August, with a peak in July. This temporal pattern underscores the importance of understanding the reproductive dynamics of the frigate tuna populations in this region. [ABSTRACT FROM AUTHOR]