Saved from devastating fires in Santa Cruz, young salmon must now survive in the ocean

The 6,000 coho salmon smolts, the fish equivalent of teenagers, were pulled from a 6-inch PVC pipe from their hatchery directly into Big Creek near Santa Cruz on Friday morning. Once in the water, they instinctively knew how to make their way to the larger Scott Creek and to the Pacific Ocean, where they were due to arrive within days.

“These fish have never been in the wild. They’ve been in a fiberglass tank, ”said Mathers Rowley, chairman of the board of the nonprofit Monterey Bay Salmon and Trout Project, which helped liberate the organization. Kingfisher Flat Hatchery. “When they touch the water, they know what to do. It’s something in their genetic memory.

The liveliness of the young fish was a sign of hope for a population that has all kinds of things against it. Part of California’s southernmost endangered central coast coho salmon population, the lives of the 14-month-old smolts have been ravaged by two natural disasters: last year’s wildfires and the drought this year.

They narrowly survived the August CZU lightning complex fire when it tore up the hatchery last summer, and their release on Friday was moved to ensure their passage to the Pacific was no longer possible. was not interrupted because of the drought.

“They are healthy and beautiful fish. They are survivors, ”said Rowley, who is working to raise up to $ 400,000 to repair the hatchery. “These are the fish we need.”

Coho have faced additional stress in recent years due to rising sea surface temperatures, which biologists believe could kill more adults before they move upstream to spawn.

“The particular threats these fish face have to do with air and water temperature, climate change and insufficient flow of rivers to migrate to the ocean,” said Manfred Kittel, senior environmental scientist in the California Department of Fish and Wildlife. “If you face a year of extreme drought like we are now, all of these water temperature and water flow issues are exacerbated.”

Fish migration is part of a natural and ancient cycle that has been greatly aided by the Monterey Bay Salmon and Trout Project since 1976, as logging and development have prevented their passage from a stream to ocean and back. While the wild coho spawns on their own in Marin County’s Lagunitas Creek, the people of Santa Cruz County are too precarious to rely on nature alone. Coho salmon fishing in California has not been permitted since the early 1990s.

Typically, the Monterey Bay Salmon and Trout Project, in partnership with the California Department of Fish and Wildlife, UC Santa Cruz, and the National Oceanic and Atmospheric Administration, spawn and release 20,000 to 30,000 salmon in the Scott Creek watershed, which flows into the ocean. north of Davenport (Santa Cruz County).

This year the number of fish released was much lower because many perished in the fire. On August 20, the day after the August CZU lightning complex fire in the Kingfisher Flat Hatchery, volunteers and staff arrived to find several structures destroyed and the water in the ponds containing between 60,000 and 70,000 baby fish, much too hot. This deprived the fish of oxygen and only about a third to a half survived.

“Our crew entered just after the fire. They had to move the live carcasses and take care of all the carcasses in a smoky and still hot environment, ”Rowley said. His 30-year-old home on the shores of nearby Scott Creek also burned down that night, as did that of hatchery manager Mark Galloway. Located among the redwoods on land donated by Big Creek Lumber, the hatchery had older tracks for rearing fish and a few large round ponds, including one where about 120 adults of the spawning stock also perished.

Since the fire also burned two bridges that access the hatchery, rescuers had to transport the fish over a bumpy forest road. They transferred them to several emergency detention facilities, including a hatchery in Sonoma and a few locations in Santa Cruz. Called fry at the time of the fire, and only about 1½ inches tall, they grew to 4 to 6 inches before being released.

The survivors were divided into groups. In November, about 10,000 were brought to Pescadero Creek, a watershed further north in the Santa Cruz Mountains that was not damaged by the fire and offered better conditions for young fish.

“Scott Creek is kind of a bet because he’s been burned so much,” said Joel Casagrande, NOAA fisheries biologist. The ash from the fire and the resulting erosion sediment had clouded the stream. In winter, he said, “water the color of tea and coffee came out of these slopes.”

But it has since cleared up, at least enough for the coho, it is hoped, to make its way to the ocean. On April 16, 6,000 were released from the Kingfisher Flat Hatchery, leaving the last 6,000 released on Friday.

“Barring a major storm the rest of the season, they will go very quickly,” said Casagrande. “They are ready to go now.”

Typically only a tenth of 1% of released fish return to the Scott Creek watershed to spawn, or 20 or 30 adults per typical year, Kittel said. As of this year’s release, that number will be just a handful.

It may sound hopeless, but since their life cycle is only three years, salmon could be extinct in three years without such intervention. And the Scott Creek Coho are irreplaceable, as they have evolved over thousands of years to live in this particular watershed.

“It is worth doing this, because to recover the species, we need to protect and maintain the genetic diversity of this species,” Kittel said. “The Santa Cruz fish that are part of this project are the last fish that have this genetic makeup of this population.”

Tara Duggan is a writer for the San Francisco Chronicle. Email: tduggan@sfchronicle.com Twitter: @taraduggan




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