Relationship between Cololabis saira fishery distribution patterns and sea surface temperature front in the Northwestern Pacific Ocean

Pacific saury (Cololabis saira) fishery in North Pacific Ocean (NPO) is one of the most important components for Chinese fishery industry. The distribution of fishery is significantly related to the sea surface temperature (SST) and its variations. In this study, the sea surface temperature gradient (SSTG) and temperature fronts are derived from SST remote sensing data. In addition, data from Chinese saury fishery in the NPO during 2013 to 2015 (not including the fishery data of Chinese Taipei) are used to analyze the spatial and temporal relationship between the temperature front and the saury abundance. The results show that the main Saury fishing grounds are mainly located in 37°–49°N, 145°–165°E. The catch per unit effort (CPUE) is negatively related to the SST in the range of 10–14 °C. In contrast, CPUE increases with the sea surface temperature in the range 14–17 °C. The most suitable temperature is between 12.5–14.5 °C. The CPUE is significantly linear positively correlated with SSTG in the range of 0.01–0.06 °C/km, then the best range of SSTG is 0.01–0.05 °C/km. Furthermore, the locations of fronts of the study area are also positively correlated with CPUE with the high correlation coefficient of 0.81. The distance (DIST) between CPUE and front shows seasonal variations. During Jun–Aug, when DIST less than 100 km, CPUE displays a positive relationship to DIST with R² of 0.85. CPUE negatively correlates with DIST and the R² is 0.9 during Sep–Nov, when the 90% fishing grounds are concentrated within the area, the DIST is less than 50 km. Results show that the SST significantly affects the migratory distributions of saury fishery. Cold water wedges and temperature fronts are concentrated near the intersection of Kuroshio and Oyashio, where the group of saury is clustered to form a high-yield fishing ground.