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農委會農業菁英培訓計畫-鰻魚洄游產卵之生態資源研究

  • 日期:111-10-25
  • 計畫編號:110農科-1.3.1-科-a6
  • 年度:2021
  • 主持人:周爰瑱

歐洲鰻(Anguilla anguilla)是降海洄游型魚類, 從位於馬尾藻海西南部的海藻床開始,仔稚魚穿過大西洋,隨著墨西哥灣流向歐洲海岸漂流,到達歐洲和北非大陸坡後,鰻魚幼蟲變態成透明的玻璃鰻,進入河口。在過去的40年裡,該族群數量急劇下降,在歐洲的一些河流中,鰻魚的資源量已經不到1980年代的1%,因而在2007年被列入《瀕危物種國際貿易公約》附錄 II。目前造成這種急遽下降的原因尚不清楚,但棲息地的減少、遷徙障礙和漁業活動可能在這其中扮演了重要的腳色。然而,鰻魚在海洋洄游的生活史階段難以進行追蹤,導致了有關鰻魚幼蟲生活史的數據相當缺乏。仔稚魚遷徙的持續時間和路徑是資源管理相當重要的基礎數據,但目前仍然存在爭議,進一步了解這階段的生活史有助於提高我們管理和保護。
在這裡,該研究嘗試個體的遷移模型的應用於了解鰻魚初期生活史之洄游路徑,並發現當使用日朗格模型進行模擬時設定模型的深度為表層和增加分辨率至1度時,遷移時間較為符合目前觀察值。仔稚魚無主動游泳的下穿越大西洋抵達河口預估時間可長達2年,建議明年度研究可將主動運動之行為納入可量。在正NAO指數之年分鰻魚仔稚魚能抵達目的地機率相比於負NAO指數的年份更低,表明鰻魚仔稚於洄游受到氣候明顯之影響。

研究報告摘要(英)


Anguilla anguilla is a catadromous fish, that go through one of the longest drift from the spawning area recognized in the southwestern Sargasso Sea across Atlantic Ocean towards the European coast with the Gulf Stream. After reaching the continental slope of Europe and North Africa, eel larvae metamorphose into
the post‐larval transparent glass eel to the fresh water. Over the last 40 years, the stock have faced a critically decrease, In some European rivers, eel recruitment is lower than1% of levels compared to that in 1980s, and it was listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora in 2007.The reasons of this decline are still unclear, but the habitat modification, migration barriers, and fisheries might play a role . However, the difficulty of observing eels during their marine life stages cause the gaps in knowledge concern the larva life stages of eels. the duration of larval migrations and the oceanic trajectories of larvae are fundamental to population dynamics, but it remain controversial. The knowledge of understanding of eel recruitment is urgent need to improve our for management and conservation purposes. the migration duration remains controversial.
Here, the study attempts to apply the individual migration model to understand the migration path of the eel.The results shows when model set up the resolution as 1 degree, the average migration time would be more similarly with the current observations. The estimated time for larvae to cross the Atlantic Ocean to reach the estuary without considering active swimming could be as long as 2 years. The success rate of reaching estuary would higher when NAO is negative.