Smolt Monitoring Project Week 9: Data

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Scott Putnam

By: Sam Hultgren; Fisheries Technician - Data Coordinator

As the season winds down for the Snake and Salmon River mainstem smolt traps, the last of the data are being collected, reviewed, and submitted.  Over the course of the 2021 season (March – May), the number of fish that have been PIT-tagged at the Snake and Salmon River traps are 3,245 and 6,336, respectively.  The data from these fish are uploaded to the PIT Tag Information System (PTAGIS; and Fish Passage Center (FPC; regional databases.

The livewells on the traps can hold several thousand fish each day. Not all of the fishes are PIT-tagged, nor are they targeted species.  Spring-summer Chinook salmon and steelhead trout are the primary focus for tagging at these traps.  Only a subset of the total fish trapped are tagged each day.  On most days, the number of untagged fish is significantly greater than those receiving tags.  Other salmon species along with other freshwater and warmwater fish species are also caught incidentally.  The crew records their information before releasing them and the data are sent to FPC to be used as valuable aids for managing our fisheries resources.

All of the trapping data are available for use by federal, state, and tribal agencies, utility district organizations, universities, and the general public.  The data are used to monitor movement patterns, timing, and survival of salmon and steelhead trout in the mainstem Snake and Columbia rivers as they migrate to the ocean. The data from these traps can also be used to monitor the potential impacts that environmental conditions have on juveniles in this migration corridor.  Recommendations can then be made to resource managers to improve migration conditions such as increasing flow over a spillway or modifying fish passage structures.

Idaho Department of Fish and Game and the Fish Passage Center cooperatively operate this fish trap as a key component of the Smolt Monitoring Program and the Comparative Survival Study. More information about these important wild salmon and steelhead trout projects is available at

For more information on Idaho’s wild salmon and steelhead click here.

  • Sooty Shearwater

    Why is a New Zealand bird picture in an Idaho fish trap blog?

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    Peter Steward flickr_cc_by_nc_2.0