One of the best adult fish counting technologies is the Riverwatcher Fish Counter, which  FISHBIO has used to collect data on upstream migrating salmon and other fish species since 2004. Infrared scanning technology and high resolution cameras create an automated process for remotely monitoring fish. FISHBIO constructs a variety of weirs to install Riverwatchers for fish monitoring in large rivers, as well as elevator systems for deploying the devices in fish ladders and fishways. Riverwatchers provide automated fish counts and body size measurements, while users can identify fish species and validate fish counts based on silhouette images and photographs. 

A basic Riverwatcher set up consists of 1) an in-river scanner unit and 2) a control unit housed in a weatherproof enclosure on the river bank. The scanner consists of two plates mounted vertically in an aluminum frame with an opening 12 inches wide and 22 inches high. When a fish swims between the scanner plates, the infrared beams are broken, which generates a silhouette image of the fish. Riverwatcher units can also be used in conjunction with a digital camera that records video or still images. Data on passage date and time, fish size and speed, and water temperature, as well as digital and scanned images, are collected for each passing fish and sent to the control unit where the information is stored.

Data files can be downloaded from the control unit as frequently as needed. Database software (WinAri) is provided for processing the data and can display information associated with each fish passage. Users can refer to the infrared silhouette as well as photos or video to identify the species and sex of passing fish based on differences in morphology. Data are only collected during passage events, meaning that users do not have to watch hours of video to locate fish. The program includes tools to evaluate run size, timing, fish size classes, and associated environmental factors. The database can also be exported from WinAri for further analysis in other programs. FISHBIO is a North American distributor of the Riverwatcher and provides services related to installation, maintenance, and data management. Contact us and explore the Riverwatcher brochure to learn more.


Peterson, M.L., A.N. Fuller, and D. Demko. 2017. Environmental factors associated with the upstream migratory activity of fall-run Chinook salmon in a regulated river. North American Journal of Fisheries Management 37: 78-93. DOI: 10.1080/02755947.2016.1240120

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