State and federal fisheries experts have successfully captured and transported 26 spring run Chinook salmon stranded in Butte Creek near Chico. The fish, which are listed as threatened under the federal Endangered Species Act, had stopped their migratory journey through the lower reach of the river because of rising water temperatures. The rescue effort by the California Department of Fish and Game (DFG) and the National Oceanic and Atmospheric Administration (NOAA) included netting the fish, implanting radio transmitters in them and moving them upstream to cooler water so they can continue their spawning migration.

“Without human intervention to capture and move these fish, we would have seen a high mortality rate,” said Joe Johnson, DFG fishery manager. “The radio transmitters we implanted will enable us to track where the salmon go and determine what the results ultimately are for this type of rescue.”

The water in the Butte Creek pool where the fish were stranded is significantly warmer than the rest of the river, creating a “thermal block” that causes the migrating salmon to dive to the bottom in search of cooler waters. As long as the water remains warm, the fish will not move forward. This particular spot on the river has been a “trouble spot” for spring run salmon in previous years and have resulted in other successful rescue and transport operations.

DFG fisheries staff and NOAA biologists solved the problem June 30 by transporting the fish up river for release, thus moving them around the warm water thermal block. Seine nets were initially used to capture the stranded salmon; biologists then used dip nets to move them to a net pen. The fish were transferred up a steep bank manually by a line of workers, and then loaded into a hatchery truck for transport and release.

DFG, NOAA and UC Davis staff also implanted all 26 of the rescued salmon with tracking devices. The trackers will enable biologists to monitor how rescued fish behave after being rescued and if they contribute to the overall salmon population.

Since 1999, Butte Creek’s spring run Chinook salmon have been listed as a threatened species. More than $35 million has been spent by state, federal and private parties on restoration and recovery efforts on the watershed.  Over the past decade, changes in habitat and water management have helped the population rebound somewhat, but Central Valley salmon populations can still vary significantly from year to year. Over the past ten years, the run has averaged 6,000 fish, but today, surveys indicate a much lower salmon return. 

Because of the low number of returning Sacramento fall run Chinook salmon, all ocean salmon seasons and the majority of inland salmon seasons, including Butte Creek, are closed.