Didson Sonar Project

Accurate counts of salmon returning to their natal rivers and streams to spawn the next generation is a fundamental aspect of fisheries management, especially in river systems such as the Kenai where multiple user groups actively seek to harvest surplus salmon above the needs for the healthy reproduction. Murky conditions and multiple fish stocks, both common to the Kenai, can make accurate fish counting a difficult task. KRSA supported and helped fund ADFG’s innovative research on and the transition to the next generation of fish counters – the Didson Sonar. In 2000 and 2002, KRSA funded infrastructure to improve counting for both chinook salmon and rainbow trout. Where there were once two recorder-beams, this project allowed for 96; where there was once a static blip on the screen, now there is dynamic video; where counts depended too heavily on the fine art of interpretation, now numbers rest upon much simpler identifications. Didson sonar was a quantum leap in improving fish counts on the Kenai and elsewhere.