山东半岛东南部海域星康吉鳗资源密度时空分布及其与环境因子之间关系

为了解山东半岛东南部海域星康吉鳗资源密度时空变化及其与环境因子之间的关系,实验根据2016年10月和2017年1月、5月、8月山东半岛东南部海域4个航次底拖网调查数据,利用广义可加模型(GAM)分析了星康吉鳗资源密度时空分布特征及其与环境因子之间的关系。结果发现,星康吉鳗资源密度及分布具有明显的季节变化。春季,山东近海星康吉鳗资源密度为66.38 kg/h,夏季资源密度达到一年中最大值,为87.31 kg/h,秋季资源密度为79.01 kg/h,冬季资源密度大幅度降低,仅为10.44 kg/h。GAM模型结果显示,水深和海水底层温度对星康吉鳗资源分布影响最大。春季,星康吉鳗资源密度与水深、底温呈正相关关系,其分布范围较广,主要分布在海州湾中部海域(35°N沿线分布最多);夏季,其空间分布受水深影响,主要集中分布在水深20～30 m的山东半岛南部近岸海域;秋季,水深、底温、饵料生物量与星康吉鳗资源密度呈正相关,此时星康吉鳗分布较分散。冬季,星康吉鳗资源密度与水深呈正相关,此时主要分布在受黄海暖流影响的海州湾北部海域以及123.5°E～124°E海域。研究表明,星康吉鳗资源分布与其洄游习性和海域水温等水文特征的季节性变动有关,其分布特征在春季、冬季分别受青岛冷水团与黄海暖流影响显著。本研究有助于了解山东近海星康吉鳗群体的生活习性,为其资源的养护和管理提供依据。

Relationship between spatio-temporal distribution of Conger myriaster and the environment factors in the southeast waters of Shandong Peninsula

Environmental changes have caused shifts in the population abundance, size structure, and habitat distribution of many marine fish species, and the impacts tend to aggravate with the future global climate changes. A better understanding of the relationship between the fish distribution and environment is helpful in coping with the further changes of climate and fisheries. Based on survey data of fishery resources and the habits collected from 99 stations in January, May, and August, 2017 and October, 2016 in Shandong offshore, we analyzed spatiotemporal distribution of Conger myriaster, and examined its relationship with environmental variables, including water depth, bottom salinity, bottom water temperature, bottom sediment types and prey density, using generalized additive model (GAM). The result showed significant seasonal variations in the distribution of C. myriaster. The stock density was 66.38 kg/h in spring, 87.31 kg/h in summer, 79.01 kg/h in autumn and 10.44 kg/h in winter. GAM identified depth and bottom water temperature as the major influencing environmental factors. In spring, both depth and sea bottom temperature had positive correlations with resource density of C. myriaster which was primarily distributed in the central part of Haizhou Bay, especially at latitudes 35°N. In summer, stock density of C. myriaster was influenced by water depth, and mainly distributed in the south coastal waters of Shandong Peninsula. Water depth, water temperature and prey density had positive relationships with resource density of C. myriaster in autumn. In winter, resource density of C. myriaster had a positive relationship with water depth, and north of Haizhou Bay and longitude 123.5°E-124.0°E were its main distribution area. The distribution of C. myriaster might be attributed to its migratory habits and the variation of the environment conditions caused by seasonal changes, such as water temperature, Qingdao cold water mass and Yellow Sea warm current.