Determining the effect of multiscale climate indices on the global yellowfin tuna (Thunnus albacares) population using a time series analysis

Abstract

The yellowfin tuna (Thunnus albacares; YFT) is a crucial species because it is the second most fished tuna globally. In this study, we analyzed the standardized catch per unit effort (CPUE) to determine the influence of climate indices on YFT distribution and fishing vessel dynamics. The standardized CPUE in the western Pacific Ocean was significantly correlated to the Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (NPGO) with a 1-5 year lag. These CPUE-climate index relationships were also observed in other ocean basins but with lower significant correlations. The Atlantic Multidecadal Oscillation (AMO) and standardized CPUE were significantly negatively correlated in the Atlantic, eastern Pacific, and western Pacific Oceans and positively correlated in the eastern Indian Ocean with a 1-5 year lag. The wavelet analysis revealed approximately 8-16-year periodicity across 1971 to 2010 between the standardized YFT CPUE and multidecadal climate indices (AMO, PDO, and NPGO). This finding suggests that decadal climate indices affect both YFT regional distributions and the long-term availability to fisheries, which may affect overall abundance. Two interannual climate indices, the Indian Ocean Dipole (IOD) and Oceanic Nino Index (ONI), were significantly correlated with the center of gravity of fishing grounds in the adjacent ocean basin. Furthermore, the influence of climate indices on the longitudinal centers of gravity was mostly limited to adjacent basins, which suggests that climate phenomena have wide-reaching teleconnections that affect large areas across and between basins.