- 學位論文
以耳石日周輪研究菲律賓太平洋雙色鰻之早期生活史
Study on the early life history of Anguilla bicolor pacifica in the Philippines by using otolith microstructure
摘要
因日本鰻的鰻苗資源短缺，導致鰻魚養殖產業式微。東南亞各國以屬於熱帶鰻的太平洋雙色鰻 (Anguilla bicolor pacifica)作為新興替代物種。到目前為止，太平洋雙色鰻的研究相當有限，其早期生活特徵仍鮮為人知。因此，本篇研究的目的為探討太平洋雙色鰻的早期生活史，進一步提供其在生態上的了解。 前人研究顯示，沿著洋流漂送路徑，鰻苗距離產卵場越遠，其平均柳葉期就越長。本研究收集台灣宜蘭、民答那峨洋流與西里伯斯海交界的Genreal Santos與西里伯斯海環流周遭的Cotabato地區之太平洋雙色鰻鰻苗樣本，並整合分析前人在呂宋島Cagayan 、Baler以及民答那峨島Mati、印尼Dumoga地區之耳石資料，探討體長、柳葉期及成長速率的時空差異，描繪菲律賓地區太平洋雙色鰻之早期生活史。 研究結果發現，平均體長在六個河口間沒有顯著的統計差異；線性迴歸分析發現，體長和柳葉期之間無顯著關係，顯示太平洋雙色鰻屬於體長依賴型的變態模式，而柳葉期和抵達河口捕捉到之日齡呈現高度正相關，表示越早變態的樣本會越早抵達淡水棲地。沿著NEC採集的夏季樣本中 (除了Cotabato以外) 的樣本都呈現了:距離產卵場越遠，柳葉期越長的關係；然而冬季在General Santos、Cotabato、Dumoga的樣本之柳葉期都明顯小於其他地區。搭配成長速率與洋流流速判定，推測來游至General Santos之玻璃鰻來自兩個產卵場，其夏季族群來自NCE，而冬季族群可能來游自西里伯斯海的產卵場，且支配著Cotabato與Dumoga 地區玻璃鰻的來游。
並列摘要
Regarding the collapsing aquaculture industry of eel resulted from the shortage of Japanese eel (Anguilla japonica), tropical eel (Anguilla bicolor pacifica) becomes an alternative species for aquaculture. However, few studies have been investigated in the early life history of A. bicolor pacifica. Therefore, the aim of this study is to further expand the knowledge about the early life trait of A. bicolor pacifica. In literature, if the glass eels are captured along the route of ocean currents, the farther from the spawning site, the longer the larval duration (LD) will be. In this study, the otolith microstructure of A. bicolor pacifica glass eels collected in Yilan (Taiwan), General Santos and Cotabato (Mindanao Island) was investigated to elucidate the early life history of A. bicolor pacifica in the Philippines by analyzing their total length (TL), LD, age at capture and growth rate. To contribute integral information and in-depth research in the analysis of otolith, previous data collected by other researchers in Yilan (Taiwan), Mati (Mindanao Island), Cagayan and Baler (Luzon Island) and Dumoga (Sulaweisi) are included. Here, we found that the TL of the glass eels did not significantly differ among 6 estuaries, and that the relationship between the TL and the LD of glass eels was not significantly related, suggesting that larvae undergo metamorphosis when reaching a certain body length. Meanwhile, the age at capture and the LD presented significant positive relationship, indicating that the larvae with earlier metamorphosis recruit to their freshwater habitats faster than those which enter the metamorphosis afterwards. The captured glass eels along the routes of ocean currents exhibited a geographical cline in summer, with a longer LD farther from the spawning site, except for samples collected in Cotabato, while samples collected in Cotabato, Dumoga and General Santos in winter had a significant shorter LD and a faster growth rate. Considering the current speed, the distance and the growth rate, glass eels recruiting to General Santos are more likely to originate from two spawning sites: the NEC in summer and the Celebes Sea in winter, wherein the Celebes Sea may also be the spawning sites of glass eels collected in Cotabato and Dumoga.
參考文獻
延伸閱讀
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