BEHAVIORAL AND ELECTROPHYSIOLOGICAL EVIDENCES THAT THE LATERAL-LINE IS INVOLVED IN THE INTER-SEXUAL VIBRATIONAL COMMUNICATION OF THE HIME SALMON (LANDLOCKED RED SALMON, ONCORHYNCHUS-NERKA)

Characteristic vibrational signals are suggested to be exchanged betwe en the sexes during the spawning behavior in the hime salmon (landlock ed red salmon, Oncorhynchus nel ka). To check whether the lateral line is used to detect and process these vibrational signals, we examined how Co2+, which is known to block the mechano-electrical transduction in the lateral line detector, affects both the spawning behavior and l ateral line response of the male hime salmon. The results showed that Co2+ blocked both the spawning behavior towards the vibrating model (F ig. 2) and the lateral line response to the vibrational stimuli (Figs. 5, 6), if the fish were forced to swim in the water containing 1.0 mM Co2+ for 1 to 1.5 h or longer in the presence of 0.25 mM Ca2+. 0.1 mM Co2+ had similar but weaker effects. These results indicate that the vibrational signals from the vibrating model are detected and processe d by the lateral line system to elicit the spawning behavior. These ar e the first experimental evidences that the lateral line sense is invo lved in the communicational behavior of the fish.