It’s springtime in Idaho, and that means adult steelhead are returning to their birthplace to spawn the next generation of fish. Steelhead are an anadromous fish, meaning they are born in freshwater and migrate to the ocean as juveniles, where they grow into adults before migrating back to freshwater to spawn.

This beautiful female steelhead was recently captured at our weir on the East Fork Potlatch River and released upstream to spawn. Fisheries staff previously captured this fish as a juvenile at one of the habitat restoration sites in the East Fork Potlatch River in 2020. At that time, she was about 6 inches in length and now she measures over 30 inches!

Based on PIT tag detections we can track this fish on her migration to the Pacific Ocean and her return trip back to Idaho. From this, biologists know she migrated to the ocean in 2021 and stayed there all of 2022. The map below highlights this fish’s journey back to her birthplace in the East Fork Potlatch River in 2023.

She was first detected at Bonneville Dam in July 2023 and took approximately 2 months to reach Lower Granite Dam. She overwintered in the Clearwater River this past fall and winter and then completed her spawning migration this spring. All in all, this fish traveled over 500 river miles and navigated past 8 dams to return to her birthplace in the East Fork Potlatch River. A truly remarkable journey!

To learn more about these incredible fish and the tools biologists use to study them please visit:

• Smolt Monitoring Project Week 6: PIT-tagging | Idaho Fish and Game
• History and Utility of Passive Integrated Transponders (PIT) Tags for Fisheries Studies | Idaho Fish and Game
• The A’s and B’s of steelhead, what do those terms mean? | Idaho Fish and Game