Are fisheries regulations influencing the biology and reproduction of the surmullet Mullus surmuletus Linnaeus, 1758 on the south-eastern coasts of France (NW Mediterranean)?

The surmullet Mullus surmuletus Linnaeus, 1758 is one of the main target and high value species for small coastal fisheries in the North-Western Mediterranean. Morphometric and reproduction indices of surmullet were determined in fisheries regulated and non-regulated zones neighbouring the Port-Cros National Park (South-Eastern France) in autumn 2019 and spring 2020. Total length of individuals ranged between 12 and 32 cm, with a mode between 17 and 23 cm. Significantly larger individuals were measured in the regulated fishing zones than in non-regulated ones, and in autumn rather than in spring. Females dominated in all zones and seasons, particularly in size classes > 24 cm in spring. Higher gonadosomatic index and more advanced gonadal development stages were observed in both sexes in spring than in autumn. Higher percentages of individuals with mature gonads and high gonadosomatic index were found in the fisheries regulated zone, engendering a higher reproductive potential. These results highlighted the importance of fisheries management with regard to the life-history traits of targeted fish species.