Some experiments and considerations for development of Doppler-based riverine sonars

Sonar counting devices have been utilized by fisheries biologists to estimate annual spawning migrations of anadromous salmon. Recent developments in signal detection based on the Doppler principle, and new information on fish sound scattering characteristics at the high frequencies used in riverine sonar, should result in much improved detection and classification capability. These are discussed along with some practical considerations for the deployment of sonar devices for counting fish in rivers.