大量魚苗標識與放流之研究

Abstract

魚苗放流是栽培漁業(sea-farming)中重要的一環，主要目的是強化野外的漁業資源，而標識魚類後放流再捕通常是研究魚群大小、分布、移動以及評估魚苗放流成效的方法之一。標識的方法有許多種，包括切鰭法、烙印法和刺青法等等，但這些方法對於數量龐大的放流魚苗來說，大多為昂貴且費時的，因此找出省時、成本低且檢測容易的大量標識法(mass-marking)是非常重要的研究課題。本研究針對體長4.0cm-8.5cm的黑鯛（Acanthopagrus schlegeli）及金目鱸(Lates calcarifer)的魚苗採用染色法(將魚隻浸泡在含有食用色素的水溶液中)、四環黴素浸泡法(將魚隻浸泡在含有四環黴素的水溶液中)、噴槍法(利用高壓噴槍將螢光色素打在魚的表皮)以及雙重標識法（四環黴素投餵法加上噴槍法）與一組空白組(魚隻未施與任何標識)進行試驗，黑鯛每三天一次、金目鱸每兩天一次，調查標識後魚隻的時間別殘存率、時間別標識殘留率以及水質資料，結果如下。 在殘存率方面，黑鯛的部分只有四環黴素浸泡組最低，其餘三組，染色組、噴槍組和空白組無差別(p<0.05)；金目鱸則是在四環黴素浸泡法、噴槍法和空白組之間前14天間並無顯著差異，但是染色法的殘存率明顯較低(p<0.05)，而在魚群大量死亡的第16天起，四環黴素浸泡組的殘存率高於其他三組別(p<0.05)，雙重標識試驗則是在第9天之前雙重標識組和空白組無差別，在第12天、第15天、第18天，雙重標識組均明顯高於空白組(p<0.05)。在時間別標識殘留率方面，黑鯛均以四環黴素浸泡組最高，噴槍組次之，染色組最低，空白組為0(p<0.05)；金目鱸均以四環黴素浸泡組最高，噴槍組次之，染色組最低，空白組為0(p<0.05)，雙重標識試驗第12天之前保持在90%以上，第15天為82%，第18天時為49%，第21天時為0%，空白組則全部為0%。本研究中發現黑鯛以四環黴素浸泡法表現最好，而四環黴素浸泡法和噴槍法及雙重標識法是較適合金目鱸魚苗的大量標識法，建議將來可以同時採用兩種標識法將魚苗進行雙重標識後放流，再配合漁民們的回報數據，來評估放流的成效以及野外資源量，以建立栽培漁業。

Hatchery-reared fry and released was an important part of sea-farming in order to enhance the natural fisheries stocks. The released and captured of marking fish were used to study the population size, distribution, movement, and assessment of wild population. Most marking methods including fin-clipped, branding and tattoo, etc, were expensive and time-consumed for a mass marking of released fry. Therefore, it was important to find the methods of mass-marking with time-saving, low cost and detected easily. The fry of black seabream（Acanthopagrus schlegeli）and giant sea perch (Lates calcarifer) with 4.0cm-8.5cm using the methods of dyeing, i.e., the fish immersed in the water solution containing comestible pigment, immersion in tetracycline, i.e., the fish immersed in the water solution containing tetracycline, and marking by spraying, i.e., the fish sprayed with fluorescent pigment spraying on the skin of fish, and double marking, i.e., the fish sprayed with fluorescent pigment spraying on the skin of fish after feed with tetracycline, and control group. The survival rates, mark retention rates and hydrology data were separately measured every three days for black sea bream and every two days for giant sea perch. The results were as follows. The survival rate of the immersion in tetracycline was lowest among the four groups, while those of dyeing ,spraying gun and control were not significant difference for black sea bream(p<0.05). The survival rate of giant sea perch were not significant difference for marking by immersion in tetracycline, spraying and control before 14th days, while that of dyeing was lower than other three methods (p<0.05). Since the 16th day, large number of fish dead. The survival rates of immersion in tetracycline was significantly higher than those of other three methods (p<0.05). The survival rate of double marking giant sea perch were not significant difference for double marking and control before 9th days, and was significantly higher than control on 12th days, 15th days, 18th days(p<0.05). The mark retention rates of immersion in tetracycline was the highest, spraying next highest, and dyeing was lowest, while the value of control was 0 for black sea bream (p<0.05). The mark retention rates of marking by immersion in tetracycline was the highest, spraying next highest, and dyeing was lowest, while the value of control was 0, too for giant sea perch (p<0.05). The mark retention rates of double marking giant sea perch were over 90% before 12th days, 82% on 15th days, 49% on 18th days, 0% on 21th days, while the value of control was 0. In this study, we found that immersion in tetracycline was better for black sea bream, immersion in tetracycline and spraying or double marking was better for giant sea perch. It was suggested that immersion in tetracycline and spraying can be adopted as double marking on fry of giant sea perch. In the future, combining marking and release as well as the recovered data from fishermen to evaluate the effects of releasing and the stock of wild population will benefit the sea-farming.