Effect of cross breeding with domesticated males on smolting in masu salmon Oncorhynchus masou
2016
Ohkuma, K. (Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Sapporo, Hokkaido (Japan)) | Fukuda, K. | Tojima, T. | Ono, I.
The rehabilitation of masu salmon resources, which have been declining for a long time, is strongly desired by coastal fishermen, especially in the Japan Sea region of northern Japan. Meanwhile, inland fisheries cooperatives release large numbers of riverine masu salmon, so-called 'yamame', which have been domesticated through many generations and show high growth and low smolting rates. Genetic contamination and the resulting reduction of smolting rate by the supposed cross-breeding of native anadromous female masu with the released male yamame are a serious issue. In this study, we experimentally bred anadromous female masu and male yamame, to investigate the effects on the smolting ratio. Regarding the maturation rate for young of the year (YOY) males, a higher rate was found in the Okutama-bred (OKT) group in five out of six compatible pairs, of which three were statistically significant (p < 0.05, chi-square test). As for the smolting ratio of male fish, the Chitose-bred (CTS) group showed a higher rate than the OKT group in all six pairs, and five pairs were significantly different (p < 0.01, chi-square test). Among the CTS group, almost all female fish were smoltified in every group, and the smolting rate of each group reflected the difference in smolting rate of male fish.
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