Characteristic analysis of fishing condition of saury in Northwest Pacific under different climate regimes

We studied the sea current characteristics and the difference of resource abundance in spawning and feeding ground under the effects of two climate regimes of Pacific Decadal Oscillation (PDO) based on the catch data of Pacific saury (Cololabis saira) in Japan from 1985 to 2013, and the environmental data including sea surface temperature (SST), sea surface temperature anomaly (SSTA), Oyashio and Kuroshio data. The results show that the catch per unit effect (CPUE) in warm period was slightly higher than that in cold period, and the maximum correlation coefficient was – 0.318 between CPUE and PDO index when the former lagged the latter three years. The effect of change of PDO index on SST in feeding ground was higher than that in spawning ground (P<0.05) and SSTA was negatively correlated with PDO index in spawning and feeding grounds, and the maximum correlation coefficient was obtained when the lag time was –1 and 0 year. The interannual variability of longitude flow of Kuroshio was lower in warm regime of PDO, while the average occupied area in spring of Oyashio had significant difference under two climate regimes (P<0.01), and the impact degree caused by the change of cold and warm regimes on Oyashio was greater than that on Kuroshio. The results show that two different climate regimes have annual fluctuation influence on saury resource in the Northwest Pacific by affecting SST and sea state condition of spawning and feeding grounds.