碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 104 / Pompano was a economical species, it was delicious and fast-growing. They had been one of many target fish species of stock enhancement programs by the government for many years in order to increase species abundance of wild populations. Taiwan Fisheries Sustainable Development Association released 44,584 juvenile short-fin pompano (Trachinotus ovatus) with T-tags in water near Chiayi in October 2013. To understand the influence of releasing to the wild fish population, recapture started four-months after releasing and the wild pompano were also collected monthly meanwhile, in order to conduct further studies.
Comparing the relationship of length and weight between recapture and wild population, result showed that the recapture population was heavier than the wild population. Condition factor (K) of each population was calculated. The mean K-value of the hatchery (4.21) was higher than the recapture (2.55) and wild (2.69) populations. Otolith were used for age determination and growth back-calculation. After grinding and etching, a clear check at radii of 422 42 μm from the core were discovered in the recaptured fish otoliths. The otolith radii is the same as the population at releasing (396 44 μm). The otolith check is therefore speculated to be formed at releasing. The check was then used to calculate the individual growth rate after releasing, and a 2.41 times of growth ratio was calculated 1-year after releasing. However, growth equation of recapture individuals showed a slower growth than the wild population.
EPMA was further used to analyze the otolith Sr/Ca ratio from core to edge. No significant differences in the Sr/Ca ratio were found between hatchery and recapture otolith samples at 110 to 200 μm radii from the core, showing useful signatures in the hatchery environment before releasing, but significant difference were found in comparison to the wild population. Significant differences were also found in the Sr/Ca ratio between 50 to 150 μm before and after check, and that decreased after check reflected that higher salinity in hatchery. Values of Sr/Ca, Na/Ca and condition factor (K) were further used for principal component analysis (PCA), cluster analysis, and discriminant function analysis (DFA). The results showed that K play an important role in discrimination of hatchery population, with 100% of the original group correctly classified, but recapture (70%) and wild (87.5%) populations were primarily distinguished by Sr/Ca ratio. Overall, 86.7% of original group cases were correctly classified. The results suggest that otolith chemical signatures and morphological check can be used as powerful tool to distinguish fish sources.
| Identifer | oai:union.ndltd.org:TW/104NTOU5451030 |
| Date | January 2016 |
| Creators | Cai, Zhi-Yong, 蔡之庸 |
| Contributors | Wang, Chia-Hui, 王佳惠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 75 |
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