Coho Salmon of Redwood Creek

Captive Rearing

What’s Happened to Redwood Creek’s Coho Salmon?

The National Park Service has been monitoring endangered coho salmon in Marin County creeks since 1997, and while their numbers have fluctuated over time, there has been an unmistakable downward trend. Their numbers are currently so low in Redwood Creek that they may soon go extinct in this stream.

The coho’s challenges extend beyond just Redwood Creek, as habitat loss, overfishing, drought, and changes in ocean conditions have led to a dramatic decline in their populations throughout Central California.

For decades, federal, state and local agencies, as well as many other organizations and individuals have worked hard to sustain the Central Coast coho population. Within the Redwood Creek watershed, large-scale restoration projects at Muir Beach and Banducci Ranch have reversed some historic coho habitat losses. Other projects, including removal of culverts and fish barriers and streamside planting, have also improved stream conditions.

Why Captive Rearing?

In spite of all these efforts, the coho salmon population in Redwood Creek has fallen to single digits in recent years. Habitat restoration alone cannot ensure their long-term viability, as their population is now too small to maintain itself through natural reproduction.

To avoid losing Redwood Creek’s coho forever, a coalition of scientists and land managers will collect juvenile coho from the creek, rear them and then release the adults back to the stream to spawn. Captive rearing is a temporary measure that has been successfully used elsewhere to increase the number of young fish that survive to adulthood, and can then naturally reproduce in the wild.

The project will:

  • Collect up to 200 juvenile coho (approximately 10 – 15% of the population) from Redwood Creek for three years (2014-2016)
  • Rear these juveniles at Warm Springs Fish Hatchery in Lake Sonoma
  • Release adult coho back into Redwood Creek, where fish will seek mates and spawn naturally
  • Survey and track populations following each release to determine how many released coho spawned successfully

Collaborating agencies

California Department of Fish and Wildlife, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Army Corps of Engineers, California Department of Parks and Recreation, National Park Service, Golden Gate National Parks Conservancy, and Friends of Lake Sonoma.

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Did you know ....

  • Coho salmon and steelhead trout are born in freshwater, but migrate to the ocean to mature. They return to their birth streams to spawn.
  • Coho salmon spawn only once, when they are 3 years old.
  • Females can lay between 1500-3000 eggs, but only 200-300 will likely survive to adulthood in an average to good year. Of those, single digits will survive to spawn.
  • Coho in Redwood Creek are genetically distinct from coho in other Central Coast stream.
  • Redwood Creek salmon are listed as endangered species under both state and federal law. Other populations of coho salmon are not listed as endangered.