The Spatio-Temporal Changes in the Long-Line Fishing Grounds of Albacore (Thunnus alalunga) in Western and Central Pacific Ocean

Abstract:

Albacore (Thunnus alalunga) is an important economic fish species in the long-line tuna fisheries in western and central Pacific Ocean, and it is also one of the major species that the Chinese long-line fleets target in this area. To explore the spatio–temporal changes in the fishing grounds of albacore and provide guidance to the long-line fishery practice, we studied the relationship between the catch per unit effort (CPUE), the monthly catch and the sea surface temperature (SST), and analyzed the geographical changes in the fishing grounds using the frequentness accumulation method. The statistical analysis was based on the data collected from 10 albacore long-line fishing vessels of China National Fisheries Corporation (CNFC) from Feb. 2011 to Jan. 2012, combined with the environmental factors such as the SST. The results showed that in western and central Pacific Ocean, the temperature at the depth of 200 m and 150 m remained stable in a year but SST fluctuated dramatically and thus had great effects on the distribution of fishing grounds and CPUE. In a year (Feb. 2011 to Jan. 2012) the fishing ground moved periodically from 14S to 26S then back to 14S. To the north of 20S the fishing ground existed all year long, and the high catch and high CPUE were present in the area where SST was 28–29℃. To the south of 23S the fishing ground only existed from May to August because the adverse weather conditions in other months imperiled the fishing vessels, and the high catch and high CPUE were present in the area where SST was 22–24℃. In this time window the catch accounted for 27.6% of the yearly total catch while the fishing vessels worked for only 14.4% of the yearly total fishing days. Given the enhanced anti-wind and anti-wave features of fishing vessels and gears, a new sustainable fishing ground of albacore could be explored and exploited to the south of 25S.