Behavioral and morphological comparisons of newly emerged white-spotted char, Salvelinus leucomaenis, in two tributaries of the Kame River, southern Hokkaido, Japan

Abstract

Many local populations of white–spotted char (Salvelinus leucomaenis), a widespread Far East Asian species, persist in above–dam areas, even when erosion control dams prevent continuing upstream movement of individuals. Four morphological characters (dorsal fin height, body depth, caudal peduncle depth, and eye diameter) and two behavioral traits (settlement time and number of foraging actions) of S. leucomaenis fry were compared between two tributaries, one above an erosion control dam and the other an unrestricted stream. Dorsal fin height and caudal peduncle depth were smaller, and settlement time during daytime longer in the above–dam fry, which also showed less frequent foraging behavior than unrestricted stream fry during nighttime, suggesting that the former had unsuitable morphology for swimming and a lower wondering tendency. These characteristics may ultimately aid survival of the above–dam population.