Spatial-temporal changes in western and central Pacific warm pool and their impact on distribution of Katsuwonus pelamis

The western and central Pacific tropical waters are largest fishing ground for the skipjack tuna (Katsuwonus pelamis) in the world. To rationalize the development and utilization of the fishery resources of K. pelamis free-swimming school fishery in the Western and Central Pacific Ocean, we derived the gravity center by calculating the resource abundance index based on the data of for skipjack tuna from 1995 to 2019 from the Western and Central Pacific Fisheries Commission. Besides, we conducted a Pearson correlation analysis by combining sea surface temperature (SST) and Oceanic Niño Index (ONI). The results show that the catch per unit effort (CPUE), which can be used to characterize the resource abundance of the gravity center of free swimming school of skipjack, was significantly correlated with the longitude of the gravity center of the warm pool and the longitude of the right edge. The relative positions and trends of the CPUE and warm pool indicators (Longitude of the gravity center of the warm pool and longitude of the right edge) were different under different climate modes but were the same under the same climate mode. The results show that the changes in the gravity center of the fishing grounds can be predicted by the warm pool's changes in the gravity center. By constructing the spatial-temporal distribution relationship between the warm pool field and the resource abundance, we found that the right edge of the warm pool could be associated with the spatial distribution of the free swimming school of skipjack, which provides an indication of the fishing ground boundary of free-swimming school stock in commercial fishing purse-seine skipjack tuna, and provides a scientific basis for its resource exploitation and conservation.