| Summary: | 碩士 === 國立臺灣大學 === 漁業科學研究所 === 100 === Eel is an important aquaculture species in Taiwan, Japan, Korea and China of East Asia, and the eel fry of aquaculture demand must completely rely on capture in the estuaries from fishermen. However, the glass eel resource has been declining rapidly from 1970-1980. In the Western North Pacific, Taiwan and northern Luzon Island of the Philippines are important producing regions for larvae of several Anguilla species. To maintain and manage eel aquaculture industry, the research on geographic distribution and seasonal species composition of glass eel is needed. According to the DNA molecular technique, four species of freshwater eel were identified in Taiwan and Luzon Island, namely Anguilla japonica, A. marmorata, A. luzonensis (syn. of A. huangi), and A. bicolor pacifica. Several studies have revealed the life history of A. japonica and A. marmorata, but the research about life history for A. luzonensis and A. bicolor pacifica are still rare. The study investigates geographical distribution and seasonal species composition of these four species of glass eel in Taiwan and northern Luzon Island of the Philippines. The results revealed that A. marmorata was the dominant species, occurring year round in Taiwan and northern Luzon Island. While sub-dominant species in northern Luzon Island was A. luzonensis, and presented in the second half of the year, with peak from July to September. Comparing with northern Luzon Island, the amount of A. luzonensis was fewer in Taiwan. Furthermore, the relative abundance (%) of A. bicolor pacifica was rare in Taiwan and northern Luzon Island, and appeared mainly between September and March. However, A. japonica was occurred in Taiwan in winter only, and the distinct geographic tilt was observed. The results revealed that the geographic distribution and seasonal composition of glass eels of four eel species were different, and this difference may be related to reproduction seasons and recruiting temperature preferences of the glass eel.
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