Idaho Fish and Game completes fish survey in the Snake River below American Falls Dam in southeast Idaho

On Nov. 18 and 20, Southeast Region Fish and Game fisheries staff and volunteers put on waders, loaded a drift boat with electrofishing equipment, and surveyed a one-mile stretch of the Snake River from Hatchery Creek to Pipeline Access below American Falls Reservoir. During the survey, the crew captured and released 312 rainbow trout, 17 mountain whitefish, 13 smallmouth bass, 11 brown trout, and 8 cutthroat trout. Other fish documented in the survey included Utah chub, Utah sucker, and yellow perch, though these species were not targeted by the survey.

The largest trout captured was a 26.7-inch brown trout. The largest rainbow trout was 22.2 inches with the majority of rainbows measuring between 16 and 20 inches. Rainbow trout were the only species with a large enough sample to estimate abundance. In other words, without biologists finding and counting every rainbow during the survey, the sample size was still big enough to give biologists a good understanding of how many fish use that stretch of river. In this case, fisheries staff estimate that there were about 2,000 rainbow trout in that mile-long stretch of the Snake River during the survey. In fact, this level of abundance is quite typical for Idaho rivers where rainbows are found.

During the November survey, fisheries staff also put tags in 200 trout.  Anglers who catch tagged fish are encouraged to report tag numbers and capture details through Fish and Game’s Tag You're It! | Idaho Fish and Game.  This effort will help Fish and Game track angler catch rates and evaluate how fish survival varies by timing and locations of stocking. Angler tag reports will also shed more light on fish movements, including when fish get passed through American Falls Dam into the Snake River or emigrate to Walcott Reservoir.

Surveys and tagging efforts aren’t the only tools Fish and Game is using to help manage the fisheries at American Falls Reservoir and the Snake River. Since late October, hatchery personnel have released nearly 250,000 rainbow trout fingerlings and over 18,000 “catchables” into the reservoir. Additionally, Idaho Power will provide approximately 9,000 rainbows ready to take your lure or jig over the winter. 

For more information about this survey and other work being done to manage Southeast Region fisheries, please contact Regional Fisheries Manager Patrick Kennedy at 208-236-1262 or pat.kennedy@idfg.idaho.gov.