Resource status and distribution characteristics of Portunus trituberculatus before the end of summer fishing moratorium in Laizhou Bay

Based on samples collected from bottom trawl surveys before the end of summer fishing moratorium in Laizhou Bay from 2010 to 2017, the temporal and spatial distributions of Portunus trituberculatus were studied by silhouette width of clustering, with the released and recaptured data. Some suggestions were made on the resource status of P. trituberculatus in Laizhou bay. The results show that resources of P. trituberculatus in the south are obviously superior to those in the north from the spatial distribution, which can be clustered into near-shore group, far-shore group and deep-sea group by Rousseeuw index. Group assessment is reasonable. The average silhouette width of station clustering was 0.34, the similarity of the stations in the group was higher, and the clustering effect was better; the resources of P. trituberculatus have obvious interannual fluctuation from the temporal distribution, which can be clustered into good group, general group and poor group by Rousseeuw index. Group assessment is reasonable. The average silhouette width of year clustering was 0.15, the year similarity within the group was low, and the clustering effect was poor. In addition, according to Pearson correlation analysis of spatial grouping, we found that the resource status is closely related to the near-shore group, and according to SIMPER analysis of temporal grouping, we found that the resource status mainly depends on the near-shore resources. Therefore, the management and protection of the near-shore group is very important to the resource of P. trituberculatus before the end of summer fishing moratorium in Laizhou Bay. During enhancement and releasing of P. trituberculatus, it is suggested that we should not only maintain the releasing scale, but also focus on the protection and management of resources in the early days, and then effectively increase the near-shore resources and further realize the significance of the enhancement of P. trituberculatus.