| 英文摘要 |
The catch rate of the spotted mackerel is more than 70% in mackerel purse seine fishery in the northeastern Taiwan. The satellite-derived sea surface temperature (SST), fishery activity, and CTD data were used to examine the relationship of the spotted mackerel’s CPUE with oceanic features, as well as with the influence of climate changes in the upwelling and frontal fishing grounds. In La Nina, SST in the northeastern Taiwan becomes warmer. This change in temperature coincided with the change of catch amount of the spotted mackerel. Our result indicated that CPUE during La Nina was higher than during El Nino. As the vertical temperature profiles in the upwelling fishing grounds indicated, the layer of water with temperature that is 3C° lower than the monthly mean SST was uplifted to surface during La Nina. In contrast, during El Nino, this layer of water with temperature that is 3C° lower than the monthly mean SST sank to 20 m under the surface. The CPUE of spotted mackerel was also affected by the cold eddy formed by the upwelling of the fishing ground. The area of cold eddy was larger in La Nina than in El Nino. In other words, during La Nina upwelling was stronger, and therefore spotted mackerel CPUE was higher than during El Nino. The CPUE of spotted mackerel was again affected by SST gradient of the fishing ground. SST gradient was higher in La Nina than in El Nino. During La Nina years, the area affected by the reversed Kuroshio Current increased, resulting in the increase of area where the reversed current and Mainland China coaster water met. Thus, the fishing ground of spotted mackerel shifted northwestward as indicated by increasing CPUE. |