Officials from the Coleman National Fish Hatchery, in coordination with the Golden State Salmon Association, performed an experimental release of 186,000 fall chinook salmon into the Sacramento River in Butte City recently, aprroximately 80 miles downstream from their natural spawning grounds. This operation was designed to evaluate if releases lower in the river will help fish bypass predators without increasing straying rates when they return as adults for spawning.
The releases are part of a three year collaborative experiment between GSSA and the US Fish and Wildlife Service to test if survival of Coleman fish can be boosted in low water years while still getting the fish to return as adults to the upper Sacramento River Basin. The Norcal Guides Association is helping to move the net pen used in the release by providing boats and captains.
All the fish have tiny tags in them that can be retrieved years later when they return as adults to spawn. A subset of the fish were fitted with short lived acoustic tags that will trigger detections in receivers embedded at various locations in the Sacramento River and Delta. This will allow an almost instant way to compare the progress of both groups of fish as they travel down the river.
Just before the Butte City experimental release, Coleman officials released around the same amount of baby salmon into their usual release location on Battle Creek. These comparative release will help wildlife officials see which group returns at a higher rate in the coming years.