Primary Study on the Distribution of Yellowfin Tuna ( Thunnus albacares) Longline Fishery Catch and the Fishing-ground Environment of the Pacific Ocean

The yellowfin tuna longline fishery is one of the important fisheries in the Pacific Ocean. According to the collected catch data of the yellowfin tuna, sea surface temperature derived from satellite 3-level production and literatures ,the yellowfin tuna longline fishery was analysed quantitatively or qualitatively by using GIS technology. The results showed that the distribution of yellowfin tuna longline fishing-grounds are mainly located in the tropical areas, which are between 20 ° N and 20 °S. The analysis on the relationship between the catch statistics by month and the average SST indicated that the favorite monthly SST of the yellowfin tuna longline fishing-grounds is 28 ℃～ 29 ℃. The frequency distribution style of fishing-grounds is skew frequency distribution. At last, the relationship of the distribution and formation mechanism of fishing-grounds with SST, dissolved oxygen ( DO ), sea current and other environmental factors were discussed synthetically.