On May 8, CDFW released about 1 million fall run Chinook Salmon smolts into the Feather River at the Boyd’s Pump Launch facility. This experimental in-river release will provide fisheries biologists an important opportunity to study how fish respond under specific environmental conditions, as compared to fish released at other points in the river system.
Anglers have expressed concern that striped bass predation is high during this time period on the Feather River. While predation is always a threat to the young salmon, it is only one of the challenges they face throughout their complicated life cycle. The good news is that current high river flows favor increased downriver salmon survival.
“It’s critical that a portion of the population survives the treacherous journey downriver, eventually returning to pass their genes to their offspring,” said Jay Rowan, CDFW supervising fisheries biologist. “The traits those survivors pass on will help the species adapt to current conditions and better prepare them for long-term challenges such as climate change.”
Central Valley rivers like the Sacramento, Feather, American and Mokelumne have been modified through the addition of dams, river channelization and flow control. To maximize returns and allow for naturally occurring genetic variation, hatcheries in each river system have begun to utilize a variety of release strategies including trucking a portion of the fish downstream, utilizing ocean net pens and varying release sites to improve overall salmon resiliency and survival.
More than 30 million Chinook Salmon smolts are released from hatcheries throughout California’s Central Valley each year. This upcoming release of 1 million smolts on the Feather River is only one of almost 100 different releases taking place this spring up and down Central Valley rivers, San Pablo Bay, San Francisco Bay and into coastal net pens. Each release has a different intent and goals for contributions to ocean and inland fisheries, returns to the river and returns to the hatchery.
Feather River Hatchery alone will release 7 million fall run Chinook Salmon in 2019. In addition to the 1 million that will be released this week, another million will be trucked to Fort Baker in the San Francisco Bay and 5 million will be trucked to acclimation net pens in the San Pablo Bay.
Survival prospects for all releases are very good. This year’s large snow pack and high river flows are a far cry from the drought years with low clear water conditions that foster higher levels of predation, disease and other stressors. Survival out of the system should contribute to improved harvest opportunities in the near future.
Last month, CDFW released 600 spring run Chinook Salmon smolts into the Feather River. The fish were implanted with acoustic tags before their release, and preliminary data indicates that this group is showing a significantly higher survival rate as they travel downriver than fish that were released during low water years.