Relationship between the Spatial and Temporal Distribution of Squid-Jigging Vessels Operations and Marine Environment in the North Pacific Ocean

Abstract

Information and understanding of fishing activities at sea is important to fisheries science, public authorities and policy-makers. To understand the spatial–temporal distribution characteristics of squid-jigging vessels and how the marine environment affects the distribution of squid-jigging vessels in the North Pacific Ocean, operation behavior of the squid-jigging vessels was analysed by using spatial–temporal factors and marine environmental factors. The fishing effort (FE) information was calculated based on automatic identification system (AIS) data of squid-jigging fishing vessels in the North Pacific Ocean from July to November in 2017 to 2020, and the overlay maps of the spatial distribution of environmental factors and fishing effort were plotted together with four environmental variables (sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), and concentration of chlorophyll-a (Chla)). A generalized additive model (GAM) was used to investigate the nonlinear influence of the marine environment on squid-jigging fishing vessel activity in the North Pacific Ocean. The results show that fishing effort increased from July to August and then decreased from September to November. The fishing effort was highest in August. The intensity of the fishing effort suggests squid-jigging vessel operations had significant seasonal variations. The overlay maps suggest that the fishing effort of squid-jigging vessels was mainly located in areas where SST was between 10∘C and 20∘C, SSH was between −0.3m and 0.2m, SSS was between 32×10−3 and 34×10−3, and Chla was between 0.1mg·m−3 and 0.4mg·m−3. The generalized additive model indicated evidence of nonlinear relationships between fishing effort and the three environmental factors. The favorable ranges of SST, SSH, SSS and Chla for fishing effort were 15∘C∼18∘C, 0∼0.2m, 33×10−3∼34×10−3 and 0.2mg·m−3∼0.4mg·m−3, respectively. Moreover, the area beneficial to fishing effort was in 41∘N∼44∘N, 152∘E∼165∘E.