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Idaho Fish and Game


Reflecting back on 2020: A year in review- Lower Granite Adult Sampling and Lochsa River Monitoring


Sampling of adults at Lower Granite during 2020 was challenging, but with the hard work and collaboration of many stakeholders the trap was operational from March 2nd through March 24th, and July 2nd through November 12th. Although we missed the bulk of spring/summer Chinook sampling and the tail-end of the steelhead from the 2020 spawn class, we were able to reach our sampling goals for fall Chinook, Coho, Sockeye, and steelhead from the 2021 spawn class. In total, this included capturing and handling 25,600 fish (11,766 steelhead, 9,908 fall Chinook, 2,308 Coho, 1,408 spring/summer Chinook and 210 Sockeye)! 


Wild Steelhead at Lower Granite Dam with floy tag

As part of IDFG’s Wild Salmon and Steelhead Group, the Lochsa River Monitoring project consists of two juvenile rotary screw traps, an adult steelhead weir, and an instream PIT tag array. These traps are all meant to monitor and evaluate trends of wild steelhead and Chinook salmon within the Lochsa River drainage. Fish Creek, a tributary of the Lochsa, has one of the screw traps along with the adult steelhead weir. These two traps create the longest continuous wild steelhead dataset available in the state, dating back to 1995. During 2020, there were 1,111 juvenile steelhead captured and PIT tagged at the Fish Creek screw trap, and 18 unique adult steelhead handled at the weir. Four of these adults were previously PIT tagged, one of which was tagged as a juvenile at the Fish Creek screw trap on June 11th, 2016!


Fish Creek screw trap


Fish Creek Adult weir

The second screw trap on the Lochsa River Monitoring project is located just above the confluence with the Selway River, and is intended to estimate outmigration of all juveniles within the Lochsa River system. In 2020, there were 413 juvenile Chinook and 538 juvenile steelhead PIT tagged at the Lochsa screw trap. These tags will be used to monitor survival at various points throughout the life of these fish, including when they return as adults and are detected by our instream PIT tag array, located just upstream from the Lochsa screw trap. The instream array has detected 38 returning adult steelhead during 2020, four of which were tagged as juveniles at the Fish Creek screw trap, and 34 of which were tagged as returning adults at Lower Granite.


Lochsa screw trap


Adult Steelhead