2001 Volume 53 Issue 5 Pages 3-9
Distribution of the “genetically pure” wild populations of the Japanese chary Salvelinus leucomaenis which might not be hybridized with stocked hatchery-reared charr in the Yunishi Stream, a headwater of the Tone River, in central Honshu Island was estimated by “inquiring survey” during January-March period in 1996. Years and locations which hatchery-reared charr were stocked and locations of the potential upstream movement barriers (waterfalls and dams) for stocked charr were obtained at the local fishery cooperatives. For the dams, years of the construction were also obtained at the branch office of Ministry of Construction, Department of Public Works and Department of Forestry of the prefectural government. In the present study, the chary inhabiting upper reaches of the waterfalls and dams which had been constructed before the chary stocking program commenced were regarded as the genetically pure populations. Genetically pure populations of the chary were estimated to inhabit the upper reaches of fish barriers in some tributaries. Most of the barriers were dams for erosion control and some were waterfalls. Lengths of each stream reach where the genetically pure populations inhabited was exceedingly short and most of the reaches were divided into shorter length by dams without fish way. In order to conserve these local and genetically pure chary populations, fish ways should not be installed with the dams which may prevent the stocked fish from upstream movements and they should be installed with the dams constructed within the reaches inhabiting the genetically pure populations.