Physical characteristics of the spawning ground of pond smelt, Hypomesus nipponensis in Kinu River, Tone River system, central Japan

摘要

Stream bed type, water depth, current velocity and substrate size at the spawning grounds of pond smelt, Hypomesus nipponensis were studied in Kinu River, from April 15 to June 15, 1992, which is one of the inlets of the Yashio Reservoir, Tone Riversystem, central Japan. Pond smelt spawned at flat riffles and pool end from May 23 to June 6. Water depth and current velocity ranged from 10 to 50 cm and from 14.0 to 48.0 cm/s, respectively and the substrate was sand and gravel at the spawning grounds.Preservation of such environment is imporant to maintain and enhance the pond smelt population in the Yashio Reservoir.