Hypomesus nipponensis
| Hypomesus nipponensis | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Osmeriformes |
| Family: | Osmeridae |
| Genus: | Hypomesus |
| Species: | H. nipponensis |
| Binomial name | |
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Hypomesus nipponensis McAllister, 1963 |
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The wakasagi, Hypomesus nipponensis, is an important food fish native to the lakes and estuaries of Hokkaido, Japan. It has been introduced in other locations, including the San Francisco Delta of the United States. It is raised in fisheries, and is very similar in appearance to the delta smelt (H. transpacificus).
Hypomesus nipponensis
Hypomesus chishimaensis was described as being a new species in the lakes of Kunashir and Iturup in 1997 based on claimed morphological differences. After later studies failed to find these morphological differences, it regarded as an ecotype of H. nipponensis. A 2007 genetic analysis supported this classification, and recommended that H. chishimaensis not be given its own binomial designation.
Native to the lakes and estuaries of Hokkaido, Japan and introduced to the lakes on Honshu and Kyushu, the Japanese wakasagi was introduced to California water reservoirs by the California Department of Fish and Game to provide more prey for stocked rainbow trout after failed attempts to introduce native delta smelt to three foothill reservoirs. At the time, the California-native delta smelt and the Japanese smelt were thought to be separated members of the same species, H. olidus. In 1959 the CDFG imported 3.6 million fertilized eggs attached to palm fiber mats from a population in Suwa Lake, located east of Tokyo; many of these eggs were dead on arrival. The fiber mats were placed in streams feeding into six lakes and reservoirs that appeared to be ecologically suitable for the smelt. It was thought at the time that these reservoirs could be chemically treated to eradicate the fish if they were found to be undesirable. In 1972 and 1973 about 77,000 fish from the Shastina Reservoir were moved to the Almanor Reservoir in Plumas County. All attempts to introduce the fish were successful, except the Dodge and Big Bear Reservoir introductions, the latter of which may have been partially attributable to chemical treatments meant to eradicate stunted crappie and goldfish.
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Wikipedia