Evaluation Method of Fish School Response to an Approaching Vessel Using a Scanning Sonar

The response behavior of a fish school to an approaching vessel was observed using a scanning sonar. The evaluation method using six parameters which signify characteristics of school shape and behavior was proposed. In the two trial survey cruises, fifteen fish schools were analyzed, and among them five schools were identified for their changing shape, swimming direction, and swimming speed. Moreover, by continuously tracing fish schools on the sonar display, these fish schools were seen to exhibit an apparent change of school shape and behavior. Therefore, the evaluation method of fish school behavior using six characteristic parameters indicating fish school shape and behavior is useful.