Thursday July 11, 2024
Idaho Department of Fish and Game —
Bull trout can be found in many mountain streams and rivers in Idaho, but did you know there are several populations that exist in headwater streams above the Hells Canyon Dams? These streams contain resident bull trout which are smaller than their migratory counterparts. Bull trout in these headwater streams would be more resilient if migratory fish were able to spawn in these waters, but migration is currently blocked by Hells Canyon Dam.
A population of large, migratory bull trout overwinters in the Snake River below Hells Canyon Dam. Once upon a time, these migratory bull trout likely spawned in creeks upstream of the dams. But what river these migratory fish were from, and how related they were to bull trout above Hells Canyon Dam was unknown.