The relationship between ENSO and spatiotemporal distribution of CPUE of yellowfin tuna(Thunnus albacares) by purse seine in the Eastern Pacific Ocean

Abstract:

Yellowfin tuna(Thunnus albacares) is a major target species of the tuna purse seine fishery in the Eastern Pacific Ocean. Based on yellowfin tuna purseseine fisheries data in the Eastern Pacific Ocean(30°N-25°S,75°W-145°W)from 1975 to 2004 and the corresponding Nino3 index(sea surface temperature anomaly), the relationship between ENSO and yellowfin tuna stock abundance and its spatiotemporal distribution are analyzed by using grey relationship analysis method in this study. Preliminary results indicate that ENSO episodes affect the stock abundance and spatiotemporal distribution of yellowfin tuna significantly. During El Nino periods, the fishing gravity center moves to the east and the north, whereas to the west during La Nina periods. There is a negative relationship between Nino3 index and CPUE. Furthermore, there is a siginifcantly regular annual change for the location of fishing gravity center. In the spring and summer, the fishing gravity center turns to the west and to the north, but it moves to the east and the south in the autumn and winter. The CPUE of the spring and summer is higher than that of the autumn and winter.