2010-12-272024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/657436摘要：日本鰻是亞洲水產養殖的重要魚種，而商業化之人工繁殖技術尚未建立，因此養殖所需的大量鰻苗皆依賴天然捕撈，造成養殖產業的嚴重瓶頸。根據統計，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 ﹪，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。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，台灣約需10-20公噸，但本省鰻苗的捕撈量，每年約8公噸左右，鰻苗不足的缺口，大都是從中國或是日本進口補足。近年來中國大陸鰻魚養殖規模不斷擴大，早已凌駕台灣之上。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，如何管理與復育日本鰻的資源，為台灣以及東亞鰻魚產業永續發展的關鍵。本年度水試所選定臺灣北部新竹縣鳳山溪、東部宜蘭縣宜蘭河、以及南部屏東縣高屏溪，作為日本鰻標識放流地點，本計畫則選定宜蘭縣宜蘭河，增加春季放流工作。本計畫將調查三處河川鰻魚資源，進行日本鰻放流之效益評估，期能有效增加鰻苗之資源，照顧漁民之最大利益。本年度目標為： ㄧ、探討台灣地區宜蘭河、高屏溪、鳳山溪天然鰻魚族群之組成與動態變化情形。 二、探討台灣地區宜蘭河、高屏溪、鳳山溪放流鰻魚族群之動態變化情形。 三、評估放流鰻魚族群降海洄游之情形，檢討未來更適當之鰻魚放流與保育策略。 本年度預期效益為： 一、掌握台灣河川鰻魚資源的現況：包括種類組成、資源量、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。 四、種鰻之放流，除可能增加鰻苗之資源、增加漁民之收益外。幼鰻之放流，亦可增加河川 中鰻魚的資源量，成熟後，少數逃脫人為的捕抓之鰻魚，亦可下海產卵，增加鰻魚生殖群的數量。 <br> Abstract: Japanese eel is an important aquaculture species in East Asia. Because the commercial scale of artificial propagation of the glass eel has not been established yet, the needed elvers 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 the same impact. The Japanese eel is mainly cultured in Taiwan, China, Korea, and Japan, with mean elvers demand about 100 metric tons. In Taiwan, the year demand of the elver is around 10-20 metric tons, far less than the average catch of 8 metric tons. Thus, lots of elvers are imported from China and Japan. However, the aquaculture scale has been growing in China since 1990s. The unbalance of supply and demand for the elver 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 year the Fisheries Research Institute of AOC will mark and release eel stocks in Fengshan River, Kaoping River, and Ilan River. This projrct will also mark and release adult Japanese eel in the Ilan River around spring. This project will be responsible for the benefit evaluation of the eel stock releasing to efficiently increase the eel resource and fishermen benefit. The three goals of the project are: 1. To study the composition and dynamics of the wild eel population in these three rivers. 2. To study the dynamics of the released eel population in these three rivers. 3. To evaluate the spawning migration of the released eels and establish a suitable strategy for eel stock releasing. The predicted benefits of this project are: 1. To understand the current resource of the wild eel in Taiwan, including species composition, abundance, sex ration, age and growth, and maturation. 2. To understand the growth, silvering, and gonadal development of the released eel for evaluation of maturation. 3. To understand the spawning migration of the released eels by comparing with that of wild silver eels. 4. To increase the elver stocks and the benefit of fishermen. The growing juveniles in the river would also increase the elver stocks when going spawning migration in the future.日本鰻放流資源評估Japanese eelStock releasingResource assessment