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Idaho Fish and Game

Henrys Fork Electrofishing

Henry's Fork River's Box Canyon has nearly 5,000 rainbow trout per mile


The 2019 population estimate for Box Canyon, a section of the Henry's Fork, shows almost 5,000 rainbow trout per mile

To determine the number of trout in the Box Canyon section, Idaho Fish and Game biologists recently conducted the annual electrofishing surveys on this section of the Henry's Fork River in Eastern Idaho. 

"We marked fish on May 13 and recaptured fish on the 15," says F&G Fisheries Biologist John Heckel. "Based on the number of trout marked and recaptured, the estimated number of rainbow trout larger than six inches for this year (2019) was 4,924 per mile." This is an increase over Fish and Games' 2018 survey that estimated rainbow trout populations at 2,796 per mile. Heckel was also able to estimate the abundance of mountain whitefish at 3,201 per mile.

Box Canyon - Pop estimate


The average size of rainbow trout increased .2 inches in 2019 as well. "The population size structure is encouraging, given that two size classes of trout near 6 inches and 12 inches are present and recruiting to the fishery," explains Heckel. The largest rainbow trout surveyed in Box Canyon this year was 20 inches long.

Box Canyon– Size Structure