2013-03-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/657422摘要：日本鰻是台灣水產養殖的重要魚種之一，具有極高的經濟價值。而商業化之人工繁殖技術尚未建立，因此目前養殖所需的大量鰻苗皆依賴天然捕撈，成為養殖產業的瓶頸。根據估計，亞洲地區現今的日本鰻資源量相較於1970年代而言，估計低於當年的10 ﹪(Han et al. 2012)，而在台灣，日本鰻族群在過去數十年間亦有顯著的降低情形 (Han et al. 2009)。日本鰻主要的養殖國家為日本、中國、韓國、以及台灣，每年鰻苗的需求量約在100公噸左右，然而，近幾年鰻苗捕獲量頻創新低，一尾鰻苗身價甚至高達200元，困擾著整個東亞的鰻魚產業。在鰻魚資源日益下降的情況，東亞各國對日本鰻鰻苗的爭奪，在可預見的將來只會更加嚴重。因此，建立適當的日本鰻資源管理與復育方針，期能有效增加鰻苗之資源，是鰻魚產業能夠永續發展的關鍵。 本計畫擬研究人工放&#63946;之鰻魚於自然環境中之成長、成熟與遷徙動態，評估適當有效之放&#63946;方法，以作為後續辦&#63972;鰻魚放&#63946;工作之依據；此外，本計畫亦擬&#63930;解國內鰻魚棲地分布情況，評估棲地保育之重點地區。本年度將選定臺灣東部宜蘭縣宜蘭河，於4-5月間進行日本鰻的標識放流，並追蹤野放後之鰻魚之生活史動態與降海洄游情形，評估較佳之放流策略。並藉由搜集與調查各國與臺灣之野生鰻魚資源，擬定長期之保育方針。本年度目標為： (1) 辦&#63972;鰻魚標&#63996;放&#63946;，並進&#64008;後續追蹤調查。 (2) 調查人工放&#63946;鰻魚之成長情形及生殖腺成熟情形。 (3) 放&#63946;後鰻魚&#64009;河洄游之動態分析並評估與野生鰻魚之差&#63842; (4) 協助辦&#63972;河川、河口鰻魚之保育宣導。 (5) 蒐集台灣、日本、中國或韓國等日本鰻（或其他鰻）資源&#63965;用國家，對於日本鰻資源及 棲地環境調查與&#63846;育相關資&#63934;。 預期效益: 一、掌握台灣河川鰻魚資源的現況：包括種類組成、性比等族群結構、以及鰻魚年齡成長及成熟等生活史參數。 二、分析放流鰻魚於河川中之成長、銀化、以及生殖腺發育情形，評估其成熟情形。 三、藉由比較河川天然鰻與放流鰻魚之動態，了解種鰻降海洄游之情形。 <br> Abstract: Japanese eel is an important aquaculture species in Taiwan with very high economic benefit. Because the commercial scale of artificial propagation of the glass eel has not been established yet, the needed fries are all caught from the wild. This results in a serious bottleneck for the aquaculture industry. It is estimated that the current eel resource in East Asia is less than 10% in comparing to that in year 1970s. Taiwan also suffers the same impact. The Japanese eel is mainly cultured in Taiwan, China, Korea, and Japan, with mean elvers demand about 100 metric tons annually. However, the amounts of glass eel catch in recent years decline rapidly, with one piece of glass eel charging 200 NTD. This seriously bugs the eel aquaculture in East Asia. The unbalance of supply and demand for the glass eels would become more and more serious in the near future. Thus, to manage and recover the valuable eel resource is a key for the sustainability of eel aquaculture industry. This project aims to identify an efficient Japanese eel releasing method by studying the growth, maturation and migration of the released eels in the river. Furthermore, this project will also try to evaluate the eel habitats of Taiwan and identify some important hot spots of rivers for eels. The Yilan River of Taiwan will be selected for eel mark-releasing location around April-May. Their life history dynamics and downstream migration will be traced to evaluate a better stock releasing strategy. The eel resource information of East Asia countries will also be investigated to find a long term eel conservation policy. The five goals of the project are: 1. To perform eel stock releasing program in Yilan River and the following tracing. 2. To investigate the growth and gonadal development of the released eels in the river. 3. To study the migratory dynamics of the released eels in the river by comparing with wild eels. 4. To help disseminating the concept of river eel conservation. 5. To collect information about the eel catch and habitats of East Asia countries for eel resource management. The predicted benefits of this project are: 1. To understand the current resource of the wild eel in Taiwan, including species composition, sex ratio, age and growth, and maturation. 2. To understand the growth, silvering, and gonadal development of the released eels for evaluation of its maturation. 3. To understand the spawning migration of the released eels by comparing with that of wild silver eels.鰻魚放流效益評估EelStock ReleasingBenefit Evaluation