Discrimination of wild and hatchery-reared black porgy (Acanthopagrus schlegeli) using otolith elements analysis of magnesium and manganese

近年來沿近海漁業資源減少，政府及民間組織著手進行資源復育，而以魚苗放流作為增裕漁業資源的手段之一。然而欲評估放流之效果，判定野生與人工養殖放流魚是相當重要的工作。人工養殖放流魚生活史初期是在人工養殖環境下生長，繁養殖業者經常使用地下水作為部分的淡水水源，此一差異應可反映在耳石的元素組成上。一般而言，人工養殖魚若使用地下水，其鎂含量在耳石核心部分會比邊緣部分高，而錳含量則在核心部分較低。研究於2005.7.21-9.23期間，在苗栗縣通宵鎮白沙屯海域經雙重標識(先投餵含四環黴素飼料後再使用噴槍將螢光色素噴在魚的表皮)後，放流5公分左右黑鯛魚苗約十萬八千尾，並以6尾未放流至海中之人工養殖黑鯛與3尾放流再捕黑鯛的耳石化學組成為基礎，建立海洋中捕獲黑鯛來源的判別依據。分析判斷10尾海中捕獲且體表無標識之黑鯛，結果顯示6尾的耳石核心部分，鎂含量較邊緣高，呈現近似於倒V字型的分佈，另3尾的耳石核心部分錳含量較低且周圍有較高値，呈現近似於U字型的分佈，其他樣本則無明顯不同。故推測海中捕獲且體表無標識之黑鯛中，6尾可能為放流再捕魚，4尾可能為野生魚，結合鎂及錳兩元素之可判讀率為60%。據此結果將可進行過去未經標識放流的黑鯛之放流效果評估。Due to the decreasing of the inshore and offshore fishery resources, the fry had been released to enhance their stock by many organizations in recent years. The discrimination of wild and hatchery-reared individual have to be done before the assessment of released efficiency. Ground water usually used to take the partial fresh water source in numerous hatchery at early life stage of hatchery-reared fish, so that elements composition of otolith may be different. Generally, the value of otolith magnesium in nucleus zone may be higher than that of edge zone, while the value of otolith manganese in nucleus zone may be lower than that of edge zone.his study released around one hundred and eight thousands black porgy fries about 5cm, which were double marked (spraying with fluorescent pigment on the skin after fed with tetracycline) to Baishatun coast in Miaoli County during July 21 to September 23 in 2005. The discrimination criteria of captured black porgy were establish, according to six black porgy that hatchery-reared and never released to the sea, and three recaptured marked individual.he otolith elements of ten recaptured individual were analyzed. Among six, their otolith nucleus zone showed higher magnesium than that of the edge zone, the distribution is similar to an inverse of V, while three otolith nucleus zone showed lower manganese than that of the edge zone and had high value around nucleus zone, the distribution is similar to an U. Others didn’t show obvious trend. That is, four individual may be hatchery-reared fish, four individual may be wild fish, and one individual were confused. Their correct classifying rate is about 60%. It is suggested that the efficiency of previous released black porgy without any marking can be assessed using this method.口試委員會審定書............................................ i 辭....................................................... ii 文摘要.................................................. iii 文摘要................................................... iv 一章 前言................................................. 1 .1.進行資源復育之緣由...................................... 1 .2.實驗魚種簡介............................................ 2 .3.研究與利用.............................................. 3 .4.分辨放流再補魚的方式與耳石介紹.......................... 5 .5.養殖用水與耳石之關係.................................... 6 二章 材料與方法........................................... 9 .1.研究樣本簡介............................................ 9 .1.1.放流再捕魚與未知魚樣本................................ 9 .1.2.人工養殖魚樣本....................................... 10 .2.耳石處理方式........................................... 10 .3.微量元素分析使用儀器................................... 11 .4.本研究之假設前提....................................... 13 三章 結果................................................ 14 .1.實驗樣本資料與耳石中元素濃度的表示方式................. 14 .2.養殖魚................................................. 14 .2.1.養殖魚鎂元素濃度特徵................................. 14 .2.2.養殖魚錳元素濃度特徵................................. 15 .2.3.養殖魚鋇元素濃度特徵................................. 16 .2.4.養殖魚鍶及鈉元素濃度特徵............................. 16 .3.放流魚................................................. 16 .3.1.放流魚鎂元素濃度特徵................................. 16 .3.2.放流魚錳元素濃度特徵................................. 17 .3.3.放流魚鋇元素濃度特徵................................. 17 .3.4.放流魚鍶及鈉元素濃度特徵............................. 18 .4.未知魚................................................. 18 .4.1.未知魚鎂元素濃度特徵................................. 18 .4.2.未知魚錳元素濃度特徵................................. 19 .4.3.未知魚鋇元素濃度特徵................................. 20 .4.4.未知魚鍶及鈉元素濃度特徵............................. 20 四章 討論................................................ 21 .1.耳石中元素濃度分析結果................................. 21 .2.耳石中鎂元素濃度特徵與魚苗來源之關係................... 22 .3.耳石中錳元素濃度特徵與魚苗來源之關係................... 24 .4.耳石中鋇元素濃度特徵與魚苗來源之關係................... 25 .5.耳石中鍶及鈉元素濃度特徵與魚苗來源之關係............... 26 .6.使用耳石中元素濃度特徵判斷未知魚來源................... 26 .7.體型較大的放流魚探討................................... 27 .8.耳石核心輪寬比較....................................... 28 .9.耳石微化學之應用性..................................... 29 五章 結論................................................ 31 考文獻................................................... 32 錄1. 本研究欲探討之魚種...................................69 錄2. 黑鲷耳石解剖位置.....................................70 目錄 1. 耳石穿越線示意圖...................................... 40 2. 耳石分析數值示意圖.................................... 41 3. 六尾人工養殖黑鯛耳石樣本之鎂鈣比數值變化圖............ 42 4. 六尾人工養殖黑鯛耳石樣本之錳鈣比數值變化圖............ 43 5. 六尾人工養殖黑鯛耳石樣本之鋇鈣比數值變化圖............ 44 6. 六尾人工養殖黑鯛耳石樣本之鍶鈣比數值變化圖............ 45 7. 六尾人工養殖黑鯛耳石樣本之鈉鈣比數值變化圖............ 46 8. 三尾放流再捕黑鯛耳石樣本之鎂鈣比數值變化圖............ 47 9. 三尾放流再捕黑鯛耳石樣本之錳鈣比數值變化圖............ 48 10. 三尾放流再捕黑鯛耳石樣本之鋇鈣比數................... 49 11. 三尾放流再捕黑鯛耳石樣本之鍶鈣比數值變化圖........... 50 12. 三尾放流再捕黑鯛耳石樣本之鈉鈣比數值變化圖........... 51 13. 七尾未知來源黑鯛耳石樣本之鎂鈣比數值變化圖........... 52 圖13. 三尾未知來源黑鯛耳石樣本之鎂鈣比數值變化圖......... 53 14. 七尾未知來源黑鯛耳石樣本之錳鈣比數值變化圖........... 54 圖14. 三尾未知來源黑鯛耳石樣本之錳鈣比數值變化圖......... 55 15. 七尾未知來源黑鯛耳石樣本之鋇鈣比數值變化圖........... 56 圖15. 三尾未知來源黑鯛耳石樣本之鋇鈣比數值變化圖......... 57 16. 七尾未知來源黑鯛耳石樣本之鍶鈣比數值變化圖........... 58 圖16. 三尾未知來源黑鯛耳石樣本之鍶鈣比數值變化圖......... 59 17. 七尾未知來源黑鯛耳石樣本之鈉鈣比數值變化圖........... 60 圖17. 三尾未知來源黑鯛耳石樣本之鈉鈣比數值變化圖......... 61 18. 黑鯛耳石中的兩種不同型態結晶......................... 62 目錄 1. 本研究使用的19尾黑鯛樣本資料表........................ 63 2. 使用不同金屬元素之可判讀率.............................64 3. 排除儀器偏差後不同金屬元素之可判讀率...................65 4. 使用不同金屬元素判斷未知魚時之可判讀率.................66 5. 排除儀器偏差後不同金屬元素判斷未知魚時之可判讀率.......67 6. 三群黑鯛耳石核心區的平均長度、平均輪寬及95%信賴區間....6