| Summary: | 碩士 === 國立臺灣大學 === 漁業科學研究所 === 94 === 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.
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