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Restoring American River Spring-Run Chinook Salmon

For decades, the possibility of restoring spring-run Chinook salmon in the American River has been ignored.  With recent changes to the Nimbus Hatchery fish ladder and federal and state mandates to focus more on the recovery of Central Valley spring-run Chinook, it is time to recover the American River’s spring-run salmon.

The American River spring-run were never really lost.  The river has always had modest numbers of these iconic salmon that attracted fishermen and even guides each spring to the lower river below Nimbus Dam.  It wasn’t much of a secret.  It was more common knowledge and a nice complement to spring shad and steelhead fishing.  These spring-run salmon were generally believed to be strays from other Sacramento River spring-run streams and the Feather River Fish Hatchery.

The spring-run hung around all summer waiting to spawn.  They concentrated at the outlet of Nimbus Dam.  In late summer, CDFW would install the hatchery rack to force returning fall-run salmon into the old Nimbus Hatchery ladder.  A mixture of spring-run and early returning fall-run were usually trapped above the rack immediately below Nimbus Dam.  Most of these salmon died by the end of the fall spawning season without spawning.  In some years, thousands of carcasses would pile up on the upper side of the rack, a hundred yards below the dam outlet.  There was even a special carcass survey and tag return site designated for the rack site where “fall-backs” were counted and recorded in tag databases.

The “waste” of these salmon was a concern that played a part in the decade-long design and construction of the new hatchery fish ladder and retirement of the hatchery rack in 2022.

The end of the rack problem created a new problem: what to do with the early-arriving stray spring-run that collect below Nimbus Dam near the entrance to the new fish ladder.  These spring-run salmon must now either wait for the November opening of the new hatchery ladder or spawn in the river after it cools in November.

The new norm is to allowing them into the ladder in November and count and spawn them as fall-run.  The problem with this approach is that it creates a problem not unlike that which occurs at the Feather River Fish Hatchery – interbreeding of fall-run and spring-run.

I suggest CDFW and Reclamation change this strategy: operate the new ladder in spring to capture the stray spring-run to restore the once-prolific American River spring-run salmon population.  Adult spring run could be collected and sorted in the Nimbus Hatchery and then trucked up I-80 to the Middle Fork of the American River upstream of Folsom Reservoir, as the first stage of a trap-and-haul recovery project.  The second stage would be collecting-trapping juvenile salmon in the Middle Fork and bringing them back to the lower river for release.  Hopefully those released would begin to contribute to a new more genetically pure race of American River spring-run salmon.

A poor second choice would be for CDFW to separate the two American River runs like they now do at the Feather River Fish Hatchery.