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.