Hatchery will free thousands of tiny salmon in survival experiment
Editor's note: A photo that originally accompanied this story was not a picture of salmon fry. The U.S. Fish and Wildlife Service provided incorrect caption information with the picture.
Will hatchery-raised salmon have a better chance of surviving their journey to the Pacific Ocean and back if they get a 75-mile head start?
That's the question a three-year study hopes to answer for the U.S. Fish and Wildlife Service and four partner organizations.
The plan Saturday is to release 180,000 salmon fry into the Sacramento River 75 miles downriver from the Coleman National Fish Hatchery. A tanker truck will take the young salmon from the hatchery outside Anderson to Scotty's Landing in Chico for the fish's intended journey to the ocean under the Golden Gate Bridge.
"If we can boost survival of the fish by even 20% to 40%, it's a great step forward to add fish to the fishery," said John McManus, president of the Golden Gate Salmon Association.
McManus said his group proposed the experiment to the U.S. Fish and Wildlife Service and the agency agreed to give it a try.
The fish will be funneled into a portable, floating pen in the river — guided by jet boats — so they can get used to the water and get their bearings before they're set free.
The study will try to determine if the fish's chance of survival will significantly improve without more of the salmon straying, the U.S. Fish and Wildlife says.
A control group of another 180,000 salmon fry is planned for release Thursday for a comparison of results, McManus said.
The study also will be a test for the fish's homing instincts to see if they return up the Sacramento River or go elsewhere, such as another tributary. The fry each have a coded-wire tag the size of a grain of rice inserted into their snouts and when they return to spawn in several years, their carcasses can be retrieved by wildlife officials and the tag checked under a microscope.
Wildlife biologists won't have to wait a full three years to find out if the experiment is working. Battery-operated acoustic tags have been surgically implanted into the gut of 600 of the fry — half in the control group and half in the trucked salmon — so transceivers in the river can monitor the fish's progress.
Under current practices, a good number of the salmon reared and released from the Coleman hatchery are lost in their first 75 miles of swimming from Battle Creek and down the Sacramento River. There's also a high mortality rate for the fish in years when there's low water in the Sacramento River due to predators.
The salmon sent into the river this week should have a higher survival rate anyway because the river is murkier from the higher flows out of Shasta Dam, giving the fry better camouflage from their hungry predators, McManus said.
"Everybody likes to eat baby salmon. They're on everybody's menu," McManus said.
Others partnering in the study are the U.S. Bureau of Reclamation, the University of California at Davis and the Nor-Cal Guides and Sportsmen's Association.
A different experiment was tried in March 2016 to see if releasing salmon fry earlier — when they're 2-and-a-half inches long — would increase survival rates. Typically the hatchery releases fall-run chinook salmon in early April when they're 3 inches long.
This year is when hatchery officials expect to get solid data on that operation, McManus said.
Mike Chapman is a journalist for the Record Searchlight in Redding, Calif. His newspaper career spans Yreka and Eureka in Northern California and Bellingham, Wash. Follow him on Twitter @mikechapman_RS. Subscribe today!