| Summary: | 碩士 === 國立臺灣大學 === 海洋研究所 === 105 === Japanese sea bass (Lateolabrax japonicas) widely distributed from Japan to the South China Sea may show diadromous migration. However, the migratory behaviors of this species are rarely studied and still unclear. Japanese sea bass is a food fish providing from fish farming or fishery catch. Stable isotopic analysis of otoliths and muscles were conducted to clarify the habitat use of wild Japanese sea bass and to discriminate the wild population from cultured fish. Otolith δ18O values and water temperature during the corresponding period were used to predict the salinity experienced by the fish. The estimated salinity profiles suggested some Japanese sea bassentered the estuaries and rivers to forage during different life stage. However, some fish completely resided in the marine environment. The stable isotopic composition were more variable in wildfish (δ18O: -3.0 ± 1.3 ‰; δ13C: -4.9 ± 1.8 ‰, n = 18) than in the reared fish (δ18O: -4.1 ± 0.3 ‰; δ13C: -9.1 ± 0.6 ‰, n = 7). In addition,the stable isotope composition of otolith (K-W test, δ18Ooto: p = 0.025; δ13Coto: p = 0.001) and muscle(K-W test, δ15Nmus: p = 0.036; δ13Cmus: p < 0.001) were significantly different between the hatchery and wild fish.These results suggested that Japanese sea bass can use diverse habitats from rivers, estuaries to oceans. The stable isotopic compositions of otoliths and muscles are useful tools to distinguish between wild and aquaculture fish.
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