The four major spawning tributaries where native fluvial Yellowstone Cutthroat Trout spawn in the South Fork Snake River system are Burns, Pine, Rainey, and Palisades creeks. IDFG will operate and maintain the modified fish weirs and traps on all four tributaries through the spring spawning runs from mid-March through mid-July annually. Each of the tributaries have a barrier to fish migration adjacent to an upstream fish trap. Pine, Rainey, and Palisades creeks have electrical barriers and Burns Creek incorporates both a waterfall and a velocity barrier. Migrating trout will be forced into the fish trap where IDFG will hand sort individual fish on a daily basis. Cutthroat Trout will be placed upstream of the barrier and Rainbow Trout and Rainbow x hybrid trout will be removed and transported to a nearby kids fishing pond. Cutthroat Trout passed upstream will be marked with PIT tags or fin punches. Near the end of the spawning run, IDFG will capture fluvial-sized trout upstream of the fish weirs and inspect each fish for marks. The percentage of marked fish will be used as a measure of trapping efficiency. With the newly modified weirs, trapping efficiencies have been high, and we anticipate high efficiencies to continue. In order to maintain high trapping efficiencies, periodic maintenance such as slight channel modifications, removal of sediment, and replacement or repair of damaged equipment or software will be required to keep the weirs  functional.


With invasion of fluvial rainbow trout precluded in the spawning tributaries, IDFG will reduce the abundance of resident Rainbow Trout that have established populations in 9.6 km (6 miles) of Palisades Creek upstream of the fish weir. Backpack electrofishing units will be used to remove Rainbow Trout and Rainbow x Cutthroat Trout hybrids through the entire reach known to support resident Rainbow Trout. Effectiveness of the removal efforts will be evaluated using the species composition of total catch.

The second part of this contract pertains to entrainment of Yellowstone Cutthroat Trout into irrigation canals. We have previously studied entrainment of larger Yellowstone Cutthroat and other trout into the Dry Bed and other canals, but know little about the numbers of smaller, juvenile fish. We propose to quantify entrainment of juvenile Yellowstone Cutthroat Trout and other trout species into the Dry Bed Canal and determine the locations of larger entrained fish within the canal system at the end of the irrigation system. Once entrainment is quantified for both adult and juvenile trout, we propose to create a prioritized alternative list to mitigate for or eliminate entrainment and start the implementation of the best alternative(s).