Spatial and temporal patterns in pelagic fish egg assemblages in spring and late autumn-winter in eastern Beibu Gulf

Semi-enclosed gulfs play important roles in global marine ecosystems, but they are vulnerable to anthropogenic disturbance and the effects of climate change. Beibu Gulf, the largest semi-enclosed gulf in China, is characterized by complex oceanographical conditions and high fish diversity, and it is an important fishing and spawning ground for many fish species. However, little is known about where these fishes spawn. We examine spatial and temporal distributions of fish eggs and their assemblages in the eastern Beibu Gulf in spring and late autumn-winter of 2020. A total of 75 taxa of fish eggs were identified, belonging to 9 orders, 33 families and 52 genera. In spring, the taxa are dominated by species in the families Clupeidae, Leiognathidae, and Carangidae (43.62%, 19.84%, and 12.51% of the total catch, respectively); from late autumn-winter, dominant families are the Engraulidae (27.52%), Sparidae (15.08%), and Clupeidae (13.32%). Five egg assemblages are recognized in spring, and four in late autumn-winter. Of available environmental variables, the sea surface temperature anomaly, water depth, and chlorophyll-a concentrations most affect fish egg assemblages. These results provide information to inform protection of fish spawning grounds and to aid fisheries management in Beibu Gulf.