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標題: | 耳石輸紋分析在日本鰻(Anguilla japonica Temminck Schlegel)初期生活史研究上的應用 Application study of otolith microstructure analysis on the early life history of Anguilla japonica Temminck Schlegel |
作者: | 鄭普文 |
關鍵字: | 日本鰻,鰻線,耳石,日周輪,變態記號,產卵期,洄游。, Anguilla japonica,elver,otolith,daily growth increment,metamorphosis check,,birth date,migration., |
出版年 : | 1994 |
學位: | 碩士 |
摘要: | 日本鰻(Anguilla japonica Temminck & Schlegel)的初期生活史,至目前為止尚未完全明瞭。因鰻魚仔稚魚的海上採樣及人工繁殖困難,以及不同學者以耳石的微細構造研究其初期生活史,所得之結果差異頗大。因而導致對於鰻魚的初期生活史各有不同的看法。 本論文以台灣、大陸及日本等國家沿岸所捕獲的鰻線的耳石為材料,利用電子顯微鏡分析其微細構造,並嘗試去尋找柳葉魚在變態時是否在耳石上留下記號,進而計數輸數,比較不同地區鰻魚初期生活史的柳葉魚期及沿岸洄游期階段所耗費的時間,並回推其產卵期及分佈洄游概況。結果發現,日本鰻產卵期大約在6?10月間。部分學者在日輪計數上有低估的情形,以致推估的產卵期有延後的現象。在經處理後的耳石上可發現與變態有關的記號,其位置大約在耳石最大半徑的2/3處,即距原點(primordium)155.23±12.9μm附近。由耳石輸紋的計數,推測柳葉魚完成變態的時間,大約是孵化後130?160天。中國大陸閩江以南地區鰻線的變態時間較閩江以北者早。變態之後向岸洄游所須的時間,大約30?40天,有北高南低的趨勢。而臺灣西南部的鰻線向岸洄游的時間比北部者長,顯示其補給源可能是來自北部。從產卵期的一致性及柳葉魚漂遊的地理傾斜現象來看,台灣、中國大陸及日本地區的日本鰻應屬同一族群且為單一產卵場。 Due to field sampling and aquaculture of the eel larvae is difficult, the knowledge on early life history of Anguilla japonica is limited. There are many researches on the early life history have been conducted by otolith microstructure analysis, however the results obtained is not consistent. This essay was conducted with SEM examination on the microstructure of the otoliths of elvers collected from Taiwan, Mainland China and Japan, try to find out whether there are significant check in otolith during leptocephalus metamorphosis, and to estimate daily age by counting otolith growth increment. Then, the duration of both leptocephalus and coastal life stages of the elver and the spawning season was estimated and migration pathway of the fish was analyzed. Anguilla japonica spawns during June through October. A metamorphosis check in otolith was found at approximately 155.23 ± 12.9 μm from primordium along maximun otolith radius. This check could be discriminated from the abrupt change of increment width as well as phase contrast of the otolith. The leptocephalus metamorphose to glass eel at about 130?160 days after hatching, and the age at metamorphosis increased with latitude. It takes about 30?40 days in the coastal area before upstream migration. The difference of coastal rings in otolith of elvers between south and north Taiwan, indicated that the elver collected in the coasts of South western Taiwan may supply from North. The elvers collected from Taiwan, Mainland China and Japan were considered to be the same population and their migration and recruitment dynamics was described. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76022 |
全文授權: | 未授權 |
顯示於系所單位: | 漁業科學研究所 |
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