Racial Variation and Local Distribution of the Funa (Genus Carassius) in Niigata and Sado Island (A Preliminary Report)

Abstract

In order to clarify the morphological variations and geographic distribution in the races of Funa fish of the genus Carassius occurring in the vicinity of Niigata City and Sado Island of the Japan Sea, several meristic characters, intestinal pattern and chromosome numbers were examined macroscopically and microscopically. So-called Kin-buna or Naga-buna type (buergeri type) specimens were obtained in the ponds scattered on the coastal terrace and foot of the mountains of Sado Island, and irrigation system of Niigata City. However, number of gill rakers of these specimens was more numerous than that of typical Kin-buna inhabiting in Lake Jo-numa of Gunma Prefecture. In the Nishi-gawa River, a tributary of the River Shinano, individuals with tetraploid chromosomes were encountered, and it was fairly difficult to find male fish among the specimens obtained. Supposed hybrids between the endemic Naga-buna and Gengoro-buna (cuvieri type) imported from Lake Biwa were detected in Lake Fnkushima-gata, the largest lagoon in Niigata Prefecture, and the Oodori-gawa River, a tributary of the River Shinano, near Shirone City. There were found the Gin-buna type fish (langsdorfi type) with triploid chromosomes in Lake Sa-gata (a kind of lagoon), in which the Gengoro-buna were imported secondarily from Lake Toyano-gata (lagoon) of Niigata City. Noticeably, the specimens of Lake Sa-gata were all female.