Abstract
Effects of oceanic-climate changes on the abundance of Pacific saury (Cololabis saira) in the northwestern Pacific during the last half century were investigated. The abundance of both large and medium size groups of saury exhibits decadal-scale variation pattern, suggesting strong effects of decadal-scale changes or regime shifts in the oceanic environment. The abundance index of large size group saury is significantly correlated with the winter sea surface temperature (SST) in the Kuroshio region, the main spawning grounds in winter. The spatial and temporal response of large size group saury to SSTs demonstrated that winter SSTs in the Kuroshio region have marked impacts on the year-class success of the winter-spawning cohorts. The large size group saury also showed significant correlations with the Southern Oscillation Index (SOI) and Asian Monsoon Index (MOI), indicating effects of the El Nino Southern Oscillation (ENSO) and winter Asian Monsoon. Linkages between SST and SOI, and between SST and MOI demonstrated that the abundance of large size group saury were directly affected by the SST fields of the spawning grounds in the Kuroshio region in winter through large-scale atmosphere-ocean interactions such as ENSO events and the winter Asian monsoon.
