A planned release of 250,000 chinook salmon next month in Bodega Bay has a local advisory council worried about the potential impacts to protected wild fish in West Marin. 

The release, intended to boost fishing prospects, will be the northernmost release in California to date. It will also be the first release in Bodega Bay and the closest release to Tomales Bay. 

Last week, the Lagunitas Creek Technical Advisory Committee, whose members include representatives from agencies like the National Park Service and the Greater Farallones National Marine Sanctuary, sent a letter to the California Department of Fish and Wildlife detailing its concerns and requesting a full environmental review. 

Top among the worries is competition between wild and hatchery fish once the latter return to freshwater streams to spawn. 

The project, coordinated by the Golden Gate Salmon Association, is intended to bolster recreational and commercial fishing prospects for Chinook salmon. Chinook runs are facing serious trouble, leading to curtailed commercial and recreational seasons last year and this year. Just this week, Fish and Wildlife announced the complete closure of the Chinook fishery north of Horse Mountain in Humboldt County and fishing restrictions in other areas, including the Bay Area.

According to Victor Gonella, founder of the Golden Gate Salmon Association, Bodega Bay has been one of the hardest hit areas. He said “barely 1,000” salmon trollers were fishing in the Farallones sanctuary, down from 6,000 a decade or more ago.

The release project has been characterized as an experiment to help Fish and Wildlife understand both the recreational and commercial benefits of hatchery releases, as well as which streams the fish choose for spawning and how such releases affect wild salmon. 

“It will not only yield valuable biological information, but also a harvest of hope for a strapped community,” Mr. Gonella said in a press statement.

The plan is to release 250,000 young chinook from the Mokelumne River Hatchery. The fish will be contained in a floating pen for a few hours before they are released into Bodega Bay as the tide goes out. Each will be outfitted with a tag that distinguishes it not only from wild salmon but also from hatchery fish released in previous years at other locations.

The salmon association expects a “much higher” survival rate compared to hatchery fish released in the Central Valley. 

Though hatchery releases have been common since at least the ‘80s, more releases have taken place in bays than inland over the past decade, with the hopes of increasing survival rates. 

Kevin Shaffer, head of the fisheries branch for Fish and Wildlife, said the department accepts applications annually for release projects, which are reviewed internally and by an advisory committee. In the past seven or so years, his branch has approved “oceanside” projects in San Mateo, Santa Cruz, and Pillar Point in Half Moon Bay, which each saw two consecutive years of releases. 

He said the department is concerned about where the fish go and how they interact with wild populations, which is why it approved this release as a one-year study with significantly more monitoring than has accompanied past releases.

“Were concerned. It’s our responsibility to know what the fish are doing,” he said.

The Lagunitas Creek watershed is home to one of the few significant wild runs of endangered coho salmon in California, and has a run of threatened steelhead trout. Agencies like the Marin Municipal Water District have dedicated significant funds to improve fish habitat, including as part of an upcoming project meant to improve winter floodplain and habitat in Tocaloma and Jewell.

The Lagunitas Creek Technical Advisory Committee, which advises the water district, has three essential concerns about the project: that hatchery chinook could compete with wild fish for spawning grounds in the watershed; that, once hatched, wild juveniles could be crowded out of safe habitat; and that hatchery fish could bring disease.

Salmon move between freshwater and saltwater through their lifetime. They are born in creeks, where they remain for a period of time that varies by species. Then they move on to the ocean, where they live as adults before returning to freshwater creeks to lay their eggs. Typically, salmon spawn in the streams in which they were born, “imprinting” their natal streams when they are young. But since hatchery fish do not have such an imprint, they can stray to new streams.

At least one oceanside release resulted in minor straying. Gregory Andrew, the fishery program manager for Marin Municipal Water District, said Fish and Wildlife has conducted surveys on Lagunitas Creek for the past two winters to look for Chinook salmon carcasses. (Salmon often die after they spawn.) 

During the 2015-2016 spawning season, two tagged chinook corpses from a Half Moon Bay release were discovered. This winter, Mr. Andrew said 10 chinook carcasses were picked up, though he does not yet know whether any were tagged.

Lagunitas Creek does not have strong wild chinook runs. Mr. Andrew noted that in one recent winter, there were 292 coho redds, or nests of eggs, compared to just two chinook redds, though in some years over 30 have been found.

The spawning seasons for chinook and coho somewhat overlap, and “chinook tend to be the first to spawn,” Mr. Andrew said. Similarly, though chinook and coho have different lifecycles, there is a short period when juveniles overlap in streams.

Mr. Gonella, of the salmon association, said this batch of fish would only be held in Bodega Bay for a couple of hours precisely so they don’t return to that bay. “We hope they mix with Central Valley salmon and return there,” he said. 

And, he added, “We hope a good number are harvested.”