Sex ratio, oocyte development and spawning season of Mediterranean moray eel (Muraena helena) from the northern coast of Tunisia
A total of 228 individuals (120 males and 108 females) of Muraena helena was sampled from September 2018 to August 2019, in the coastal waters of Bizerte by longline. The total length of males ranged from 330 mm to 970 mm while females ranged from 310 mm to 925 mm. The eviscerated weight ranged from 55 g to 1950 g and from 38 g to 1051 g, for males and females, respectively. Our results reported a balanced sex ratio. For males, the gonadosomatic index (GSI) and the hepatosomatic index (HSI) have similar seasonal variations. However, the relative condition factor (CF) varies differently among seasons. For females, the GSI increases from autumn to summer, and the HSI reaches the maximum value in winter and decreases during other seasons. The relative condition factor values decrease slightly from autumn to summer. Histological examination of the gonads revealed that both sexes reached maturation in summer. Our histological studies confirm that the spawning period extends from late summer to early autumn.