Comparison of the swimming ability and upstream-migration behavior between chum salmon and masu salmon

Abstract

Abstract:The spawning ground of chum salmon (Oncorhynchus keta) is usually 31 located farther downriver than that of masu salmon (O. masou) in Hokkaido, Japan. To 32 compare the swimming abilities of these two species, the relationship between 33 swimming speed and oxygen consumption was compared using a swim tunnel in the 34 laboratory. Then, the upstream-migration behaviors of chum and masu salmon were 35 compared using electromyogram (EMG) telemetry at fish passages in the Toyohira 36 River, Hokkaido. In the laboratory study, the standard metabolic rate of masu salmon 37 was lower and the critical swimming speed (Ucrit) was faster than those of chum salmon. 38In the field study, the holding time needed to recover the swimming performance 39 exceeding Ucrit at the fish passages, and the trial number needed to pass the fish 40 passages were significantly lower for masu salmon than chum salmon. These results 41revealed that masu salmon are more adaptable to extended swimming in 42 high-water-velocity conditions than chum salmon and that masu salmon are better 43 equipped for a long distance upstream to their spawning ground than chum salmon.