莱州湾“伏休”结束前三疣梭子蟹的资源状况及其分布特征

根据2010—2017年莱州湾"伏休"结束前底拖网调查资料,通过轮廓系数法对莱州湾三疣梭子蟹资源的时空分布特征进行了研究,并结合放流回捕资料对莱州湾三疣梭子蟹资源状况提出了建议。结果显示,在空间分布上,三疣梭子蟹南部资源明显优于北部;依据Rousseeuw质量指数分为3组,分别为近岸组、远岸组和深海组,分组评估合理,平均轮廓系数为0.34,组内相似度较高,聚类效果较好;从时间变化上,三疣梭子蟹资源具有明显的年际波动性,依据Rousseeuw质量指数分为3组,分别为较好组、一般组和较差组,分组评估合理,平均轮廓系数为0.15,组内相似度较低,聚类效果较差。另外,空间分组的Pearson相关性分析结果表明,三疣梭子蟹资源状况与"伏休"结束前近岸组资源密切相关;时间分组的SIMPER分析结果同样显示,三疣梭子蟹资源状况主要取决于"伏休"结束前的近岸资源。因此,"伏休"结束前三疣梭子蟹近岸资源的管理与保护对于三疣梭子蟹资源的影响至关重要,建议在实施三疣梭子蟹增殖放流时,不仅要保持增殖的规模,还应重点关注前期资源的保护与管理,从而有效增加近岸资源,进一步实现三疣梭子蟹增殖放流修复的意义。

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.