Aquaculture for all

Wild Common Carp in Japan Under Threat

JAPAN - Scientists from Japan have discovered the introduction of domesticated strains of carp from Eurasia are destroying the wild carp (Cyprinus carpio)populations.

The scientists, K. Mabichi, H. Senou and M. Nishida from the University of Tokyo and the Kanagawa Prefecture Museum of Natural History, looked at the mitochondrial DNA sequences from 116 wild carp from 11 different areas in Japan.

THe results of the survey, Mitochondrial DNA analysis reveals cryptic largescale invasion of non-native genotypes of common carp ( Cyprinus carpio) in Japan, have been published in a recent issue of the journal Molecular Ecology 17, 796-809.

Of total 28 haplotypes identified, the authors believe 19 haplotypes are of Japanese native and the rest are non-native domesticated strains. Introduced animals are likely from China and Europe.

The study also revealed that almost half or more of the haplotypes in all of the locations studied originated from domesticated strains introduced from Eurasia.

Mitochondrial DNA is maternally inherited and provides no information with respect to hybridisation between native and non-native fish. However, evidence of hybridisation between native and introduced strains of common carp has been reported for German and Uzbekistan populations and "thus, it is reasonable to assume that the native and non-native domesticated strains also have hybridised in Japan. The extent to which such hybridisations have occurred should be examined immediately. Until then, we cannot eliminate the possibility that no genetically pure native strains remain," says the report.

The study reconfirmed the fact that Japanese common carp is the "most basal strain of the species identified to date" and deserves conservation attention.

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