Holding the line: What’s happening with salmon in Santa Cruz County

Salmon in Santa Cruz County live on the edge. Quite literally: Monterey Bay marks the southern extent of the range for several salmon species in California, where naturally warmer water, smaller creeks that run low or dry in summer and fewer cool places to shelter leave local populations more vulnerable than their counterparts farther north. Recent years have brought cautious optimism about a rebound statewide, with scientists and restoration groups saying salmon here are still “hanging on,” sustained by decades of monitoring and an expanding web of restoration efforts.

Salmon here remain far below historic numbers, yet signs of resilience continue to flicker. The two native species present very different challenges. Steelhead, listed as threatened, have declined gradually over time, though “not catastrophically,” said Joseph Kiernan, a research ecologist with NOAA (National Oceanic and Atmospheric Administration) Fisheries. Endangered Central Coast coho salmon populations show sharper boom-and-bust cycles. In some years, fewer than five adult coho return to spawn.

This difference is largely shaped by biology. Coho salmon return to spawn almost exclusively at age 3, meaning each year’s run depends on a single brood. When that brood encounters poor conditions, there is no secondary generation to buffer losses when environmental conditions are poor. In contrast, steelhead have more flexibility, returning to spawn at different ages and over multiple years. “The populations are very dynamic. That’s the nature of salmon,” Kiernan said.

Even with the challenges salmon face, early signs this season suggest improvement following several years of low numbers from 2020 to 2024. Ben Harris, executive director of the Monterey Bay Salmon and Trout Project (MBSTP), said counts of fish show coho salmon are successfully reproducing in Scott Creek, which flows roughly 12 miles from Big Basin Redwoods State Park to the Pacific Ocean just north of Davenport. The heavy rains late last year led to high winter flows that make it hard for scientists to conduct hands-on monitoring, but these new observations have encouraged scientists tracking the run.

Steelhead numbers have also improved modestly. MBSTP crews trapped more than 20 steelhead in the San Lorenzo River this season, surpassing totals from each of the previous three years.

Precious local records

With a few efforts happening around the county, the clearest window into these trends comes from the Scott Creek Life Cycle Monitoring Station. Now led by Kiernan, the station has been tracking coho and steelhead salmon for more than two decades, making it one of California’s most intensive salmon research programs. Outside of Scott Creek, “there is a dearth of information on salmonid populations in the Santa Cruz Mountains region, making it difficult to speak to contemporary population trends,” said Kiernan.

The station lies just upstream of Swanton Farm and down a winding dirt path, where a large metal structure known as a modern weir sits in the creek. It works much like a turnstile, gently guiding fish into a holding area without blocking the flow of water. There, scientists can count, tag and study the salmon before releasing them to continue their perilous journey upstream.

Over the course of monitoring, researchers have captured a wealth of information on how local salmon populations respond to environmental changes, including two wildfires, flooding and other challenges that have occurred in the watershed. Six years ago, a strong coho cohort emerged across Northern California, producing high returns. Santa Cruz County, however, largely missed this surge due to a drought that limited habitat availability. Even so, Kiernan noted, “we still had more fish than we would have in a normal year.” This event provides a valuable point of comparison, helping researchers understand how extreme conditions influence salmon life cycles.

Restoration in action

Because these fishes’ lives are so fragile, it takes a lot of coordination to restore populations. MBSTP’s Kingfisher Flat Genetic Conservation Hatchery plays a central role by “preserving the last genetic resources for southern coho salmon in California,” said Harris. “Without it, it’s likely that coho would have gone extinct south of San Francisco Bay years ago.”

Unlike production hatcheries, which focus on raising large numbers of fish for harvest, Kingfisher Flat operates solely for conservation. The program maintains a diverse group of adult fish used for breeding called a broodstock, carefully chosen to include a range of ages and developmental stages. Having this variety gives the broodstock’s offspring a better shot at surviving environmental stress, because a single adverse event would be less likely to wipe all of them out at once. “Basically, a diverse life history structure in the captive brood population keeps us from having all of our eggs in one basket,” Harris said.

Still, hatcheries can only do so much. Daniel Nylen, who leads the Watershed Restoration Program of the Resource Conservation District (RCD) of Santa Cruz County, said habitat destruction continues to be the primary challenge for salmon recovery in the area.

To tackle this, the RCD takes three main approaches. It improves salmon habitat by adding big logs to streams and restoring estuaries and floodplains, giving young fish safe areas to grow. It reconnects rivers by removing old dams or installing fish ladders, letting salmon reach upstream spawning grounds. The team also works to clean the water, by planting streamside vegetation to block soil and runoff from roads and farms. Cleaner water protects eggs and small fish, helping salmon survive and thrive.

One of the largest efforts is a long-term project to redesign the Highway 1 bridge where Scott Creek meets the ocean. The original bridge shifted the creek and shrank nearby marshes and estuaries, reducing crucial nursery habitat where young salmon grow, find food and gradually adjust to saltwater before heading to the ocean.

“Restoration of that part of Scott Creek has been identified as the number one recovery action for coho salmon south of the Golden Gate,” said RCD director Lisa Lurie. For more than a decade, Lurie’s team has worked with the Santa Cruz County Regional Transportation Commission and state transit agency Caltrans to evaluate ecosystem needs and reimagine the bridge infrastructure.

“We’re feeling really optimistic about the momentum of that project. We’re still several years out from implementation, but the vision there would really be significant in terms of coho recovery and other things that matter to our community, like community access to the coast and improving safety along that Highway 1 infrastructure,” said Lurie.

Human development altered natural systems over generations, and restoring ecological function in a changed landscape will continue to be challenging. “It is a long-term process and it does take sustained involvement,” said Lurie.

Those working closest to the fish say progress is real. For salmon researchers, persistence and personal connection are just as essential as population counts. “That goes way beyond anyone’s thesis. The simplest things that we can do is get outside, open your eyes, sit quietly, and observe,” Lurie said.

At the southern edge of their range, Santa Cruz County’s salmon might never rebound in large numbers, because of climate-warmed waters and habitat that humans can’t restore without abandoning homes and cities. But for now, scientists and restoration groups say every creek, every year, still counts.

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