| 英文摘要 |
After hatching, glass eels of the Japanese eel (Anguilla japonica) migrate along with the Kuroshio Current to coastal waters of Taiwan and make the final anadromous journey to grow in the upstream.? We therefore collected sea surface temperature anomaly (SSTA) at the time when the Kuroshio Current first contacted Taiwan and catch data of glass eels when the Kuroshio Current and Kuroshio Branch Current, respectively, passed the northeastern and southwestern estuaries of Taiwan to investigate the change in marine environment of these two estuaries under different climate changes and examine the variation in glass eel production.? We found that when the change in sea surface temperature of the sea of Nino3.4 was in the opposite direction of the change in sea surface temperature of the sea of southern Taiwan, and if the SSTA of the latter exceeded 0.5￠XC was continuously for 5 months, the production of glass eels became higher.? This clearly indicated that when Taiwan Nino event occurred, the flow of Kuroshio Current was stronger and, therefore, brought more glass eels to the coastal waters of Taiwan, resulting in higher catch of glass eels by local fishermen.? Through spectral analysis, we found that Taiwan Nino index and production of glass eels in the coastal waters of Taiwan appeared to have a 5+year periodic variation synchronous in time and moving in same direction.? This phenomenon clearly demonstrates that sea temperature of the coastal waters of southern Taiwan is one of the major factors to influence the recruitment of glass eels.? In the short-term analysis, we found that the periodic variation in air temperature and air pressure, in relation with glass eel production at Gongliao, respectively, were synchronous in time and moving in same direction and synchronous in time and moving in opposite direction.? It was possible that the Siberian high pressure when moved southward to Taiwan caused the drop in air temperature and rise in air pressure and hence strengthened the cold China Coastal Current, consequently, interfered the flowing of Kuroshio Current passing offshore waters of Gongliao.? The production of glass eels, which were brought to these waters by the Kuroshio, was then reduced |
