| 英文摘要 |
This study mainly estimates variability between climate and target tuna species of longline in the Pacific Ocean. Base on Lee and Nishida (2002)’s study, we separate the longliner into two types. One is deep longliner (DLL) and the other is regular longliner (RLL). And next, we also separate the fishing ground into four areas according to clustering analysis. Use these separators and generalized linear model (GLM) to discuss tuna’s variations separately.
Climate change cause environmental change clearly in the equatorial Pacific Ocean. That is the reason that our study focus on BET and YFT. These two species is major target species in the equatorial Pacific Ocean. To estimate the gravity variation of CPUE, DLL and RLL have different pattern. Due to the BET has clear separation on DLL and RLL, we analyze BET’s spatial variability in more detail. The results indicate that in the short-term climate change BET RLL CPUE gravity has similar variation with SOI. During El Nino events, the gravity moved to the east and during La Nina events, it moved to the west. However, the phenomenon were not observed in DLL CPUE gravity. Then, use GLM to discuss the interaction factors and the results summarized as follows: (1) TP*YR: DLLCPUE decease, but in 1996-1998 has higher CPUE; (2)TP*MN and AR*MN: besides AR3, BET has higher CPUE in DLL type; (3) TP*SST and TP*AR*SST: BET DLL has higher catches in 13 ℃, BET RLL in AR1has higher catches in 22 ℃.
In long-term climate change (climate regime shift), no matter what kinds of operation types, the CPUE gravity of BET and YFT in AR1 and AR4 have some variations. In PDO warm phase, the gravity in AR1 moves to the east. In cold phase, AR4 gravity moves to the west. ALB in AR1 and AR4 also affected by climate change, in El Nino year has higher CPUE. |