Characteristics of fish community structure and its relationship with environmental factors in Dachenyang spawning ground reserve

To understand the protection effect of Dachenyang spawning ground reserve, based on the survey data of fishery resources in the Dachenyang Spawning Ground Reserve in April (spring) and November (autumn) 2018, relative importance index (IRI), diversity analysis, cluster analysis, canonical correspondence analysis (CCA) and other methods were used to analyze the characteristics of fish community structure in this sea area and its relationship with environmental factors. The results showed that: a total of 83 species of fish were caught, belonging to 9 orders and 51 families, including 2 dominant species of fish, 18 important species of fish, belonging to 5 orders and 11 families, and the dominant species were Amblychaeturichthys hexanema and Harpodon nehereus. Hierarchical clustering (CLUSTER) and non-metric multidimensional measures (NMDS) analysis showed that the spring and autumn fish communities can be divided into 3 groups spatially, and there are significant differences between the community groups (P<0.05). H. nehereus, Benthosema pterotum and Thryssa kammalensis were the main divergent species that affect the seasonal changes of community structure. ABC curve analysis showed that the fish community in spring was moderately disturbed (W=0.027); the fish community in autumn was in a state of severe disturbance (W=–0.185). Canonical Correspondence (CCA) analysis shows that water depth, temperature and salinity are important marine physical and chemical factors that affect the composition of fish species and the temporal and spatial changes of community structure in this sea area.Compared with the resources in the same period in 2015 and 2017, both biomass and abundance increased significantly in November 2018. This study found that the establishment of protected areas played a protective role in the recovery of fishery resources, but long-term resource protection was needed to restore marine resources to an ideal state.