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Idaho Fish and Game

Snorkel surveys help guide habitat improvement projects in the Potlatch River Basin


Steelhead parr density data collected during snorkel surveys help fisheries and other resource managers make informed decisions to enhance their survival with habitat improvement projects.

The Potlatch River is located in northwestern Idaho. Its seasonal flows can range from a trickle in some reaches during the summer to a raging torrent in the spring.

This river contains adult and juvenile steelhead trout. Adults enter the Potlatch to spawn during late winter and early spring. They will either die or move out soon after. Their young will remain to rear in the Potlatch and its tributaries.

Idaho Fish and Game, private land owners, and other cooperators are improving steelhead trout habitat. One method involves introducing large woody debris into the stream channel to increase habitat complexity. The wood provides cover for the fish. It also helps recharge the floodplain. These treatments should generate a fish response that can be detected with appropriate monitoring.

IDFG is especially interested in juvenile steelhead, known as parr. Snorkel surveys are one method to monitor the parrs’ response to the treatments. Crews from across Idaho gather on the Potlatch each June to conduct surveys. The number of surveys each year is variable and depends upon the scale of the information needed. During 2023, crews will survey 160 sites scattered across the Potlatch River basin. They will record data about the fish and the stream environment.

Similar snorkel surveys will be conducted across Idaho this summer to benefit wild salmon and steelhead trout. They will help guide restoration actions such as identifying the need for large woody debris placement where cover is scarce or for managing water where stream channels go dry.