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研究報告

更新日期: 2015-02-09
點閱數: 1,692

人工放流鰻魚之效益評估

年度 2013
計劃名稱 人工放流鰻魚之效益評估
中文摘要 日本鰻是亞洲水產養殖的重要魚種,但因人工繁殖尚無法商業化量產鰻苗,因此養殖所需的大量鰻苗皆依賴天然捕撈。根據統計,現今的日本鰻天然資源量相較於1970年代而言,估計低於當年的10 ﹪,因此鰻苗的缺乏,遂成為養殖產業的嚴重瓶頸。日本鰻主要的養殖國家為日本、中國、韓國、以及台灣,每年鰻苗的總需求量約在100公噸左右,台灣年平均需求量約20公噸以上,但本省鰻苗的捕撈量,近年來平均在5公噸以下,鰻苗不足的缺口頗大,在鰻魚資源日益下降的情況,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。而人工增殖放流,為增加降海種鰻的手段之一。本年度計畫分別選定在北部新竹縣鳳山溪及頭前溪、南部高屏溪和東部宜蘭縣宜蘭河,進行日本鰻標識放流工作,並於宜蘭縣宜蘭河進行日本鰻成鰻之無線電標識放流,對於其遷徙習性之動態進行分析,並進行放流後之回收評估工作,期能建立一有效增殖鰻魚資源之方法。本年度計畫已完成鳳山溪、高屏溪及宜蘭河之放流回收工作以及宜蘭河無線電標籤記錄,綜合結果如下:   一、鰻魚放流後的回收: 迄2013年11月底為止,共採集野生鰻253尾,放流鰻36尾 (雌23隻、雄13隻),宜蘭河回收到的成鰻共24尾,其中有晶片的有9尾,回收率為2.8%、頭前溪及鳳山溪所回收到的鰻魚總共有3尾,回收率為0.36%,而高屏溪回收到的鰻魚有9尾,其回收率為1.9%,今年度各溪流鰻魚的回收率較往年偏低。   二、回收鰻生長與成熟情形: 宜蘭河回收鰻集中在2012年12月初捕獲。因此其體長無明顯變化,體重僅有略微下降的情形,其GSI平均值0.62,黃鰻與銀鰻皆有。其他河川並未捕獲到有晶片的鰻魚。   三、無線電標識鰻追蹤情形: 迄2013年11月底為止,共偵測到15尾無線電標識鰻魚,以GPS定位後描繪其路徑,顯示出其整體路徑往下游移動,與野生銀鰻陸續降海之習性相符。   四、協助辦理鰻魚之保育宣導工作: 本計畫已協助蘭陽博物館舉辦『白金傳奇-臺灣鰻魚展』(2012/11/27 – 2013/05/05) 之策展與相關宣傳與教育活動。   五、東亞各國日本鰻資源、棲地環境調查與復育相關資料: 2010、2011、2012、2013年,亞洲日本鰻苗總捕獲量遽降為41、35、26、19公噸,台灣在最近4年 (2010-2013) 的鰻苗捕撈量僅分別剩下4.2、4.2、1.9、1.5公噸,迭創歷史新低。
英文摘要 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 Taiwan also suffers the same impact. The Japanese eel is mainly cultured in Taiwan, China, Korea, and Japan, with mean elver demands about 100 metric tons annually. Taiwan needs about 20 tons for aquaculture but only catches less than 5tons in recent years. Thus, to manage and recover the valuable eel resource is a key for the sustainability of eel aquaculture industry. An efficient Japanese eel releasing method is one of the methods to increase migratory eels. The Fengshan River, Touchan River, Yilan River and Kaoping River of Taiwan will be selected for eel mark-releasing location. In addition, the radio-tagged silver eels were performed in Yilan River. Their life history dynamics and downstream migration will be traced to evaluate a better stock releasing strategy. The five results of the project are:   1.                 The re-catch of the eel: till Nov. of 2013, a total of 253 wild and 36 released (Female: 23, male: 13) eels were caught. 24 eels were caught from Yilan River (re-catch rate 2.8%, 9 eels with chips). 3 eels were caught from Fengshan and Touchan Rivers (re-catch rate 0.36%). 9 eels were caught from Kaoping River (re-catch rate 1.9%). The average re-catch rates were lower than they were before. 2.                 Growth and maturation of the re-catch eels: The re-catch eels from Yilan River were mainly concentrated around Dec. 2013, thus there were no significant change on total length and only slightly decrease on body weight. The mean GSI was 0.62, which covered both yellow and silver eels. 3.                 Tracing of the radio-tagged eels: till Nov. 2013, 15 tagged eels were detected. Their migratory routes were identified by GPS. The overall movement was toward the lower reach, similar to those of the wild eels. 4.                 Promotion of eel conservation: We had designed the Eel Expo in LanYang Museum between 2012/11/27 – 2013/05/05 and help the related promotion and education activities. 5.                 Collection of eel resource information: During years 2010、2011、2012、2013,The total annual catch of the Japanese glass eel in East Asia were 41、35、26、19 tons, respectively. The catches in Taiwan were 4.2、4.2、1.9、1.5 tons, respectively. The eel resource seems to become lower and lower.
計畫編號 102農科-11.2.1-漁-F4(2)
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