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Methods And Techniques For PIT Tagging Large Numbers of Small Juvenile Salmonids

Tobyn Rhodes, Ken Tiffan

U.S. Geological Survey, 5501A Cook-Underwood Rd., Cook, WA 98605

Since 1991, we have developed methods and techniques for collecting, holding, and PIT tagging large numbers of small (≥45 mm) juvenile fall Chinook salmon in the Snake River. We highlight a workflow to maximize the processing and tagging of large numbers of salmonids (e.g., 1,000 fish/day) that are collected in the field, which includes safe and efficient handling, crew resource roles, and using adapted methods to tag fish <65 mm. Minimized handling is achieved using sanctuary implements in buckets and livewell, and stressors are limited by reducing crowding during holding and minimizing exposure to increased water temperatures. Tagging and processing efficiency is maximized using a three-person crew: tagger, data collector, and fish culturist, which allows for greater focus on tagging, fish condition, and data quality. Tagging implements such as notched wet sponges and customized injectors are critical to increasing stability and control when tagging fish as small as 45 mm. Equipment organization in the small confines of a boat can speed workflow thus reducing handling times and other fish stressors. These techniques have greatly increased the number of juvenile fall Chinook salmon we can safely tag in a day with minimal mortality.