West Fork Environmental successfully deployed and operated high-resolution imaging sonar to continuously monitor adult Chinook salmon migration in the lower Skookumchuck River over three seasons. An ARIS Explorer 3000 imaging sonar was installed using a custom multi-axis mount. Site configuration included temporary guidance structures to direct migrating fish through the field of view and ensure complete coverage of the monitoring cross-section. Prior to data collection, sonar coverage was field-verified using submerged and floating targets at multiple distances to confirm that fish passage could be reliably detected throughout the monitoring area.
The sonar was operated continuously using Sound Metrics software, with data automatically recorded for subsequent processing. Biologists visited the site daily to verify equipment operation, manage data storage, and document environmental conditions, while a backup power system provided uninterrupted operation during localized power outages. Experienced reviewers analyzed recorded imagery using ARISFish software to efficiently identify fish passage events and to determine direction of travel, evaluate fish behavior, and obtain length measurements. The project demonstrated our ability to design and install an imaging-sonar monitoring station, optimize and verify acoustic coverage, maintain continuous field operation, manage large volumes of sonar data, and efficiently process imagery to generate reliable fish-passage information.