Endangered coho salmon mistreated by 3rd year of drought.  This is why it is important

Endangered coho salmon mistreated by 3rd year of drought. This is why it is important

Nossaman Pierce participated in the collection of juveniles for the initial spawner and remains cautiously optimistic. But he said he would like the region’s residents to feel some ownership of the problem and the solution.

“We nearly lost our native fish,” he said recently at the edge of Green Valley Creek as a crew tended to a smolt trap there. “Literally, this population would have disappeared a few years after the start of this program.”

At the end of last summer, members of the monitoring program mapped 36 streams in the lower watershed of the Russian River. They found that the pools that had housed about half of all coho and steelhead juveniles in previous investigations remained wet. Another 40% were completely dry; about 10% were intermittent.

It is not known how many fish died, Nossaman Pierce said.

In the winter, heavy early season rains allowed adult salmon and the Steelhead to access small tributaries they hadn’t been able to reach for years, sparking cheers from the wildlife community.

But the following months were so dry that the streams receded rapidly, leaving many of the gravel nests they had created on the edge of tall, dry shallow rifles, along with the eggs.

Observations this spring were daunting: 28 percent of the reds were dry or partially dry, Nossaman Pierce said.

Several hundred smolts and other young fish, meanwhile, have become stranded in a tributary of Green Valley Creek, said David Hines, Coho salmon recovery coordinator, senior environmental scientist with the California Department of Fisheries and Wildlife.

Usually the problem is the summer disconnect where a creek is supposed to meet the river but it dries up, Hines said. Any rescue, where an electric shock is applied to the water and the fish are quickly caught, is needed in late May or early June, he said.

With every single fish only three years old to breed in freshwater, swim to the ocean, and mature enough to return upstream to spawn, a few years of drought could prove catastrophic for the coho population, most of which she was born in the hatchery.

“This is what we are living with,” said Nossaman Pierce. “A poor year has an impact on three-year-old fish classes. And if they keep taking these hits every year, you won’t be able to walk away, even with the breeding program. Conditions simply can’t support it.

Losing ground

Since the first release of hatchery offspring into the watershed, the number of adults returning to spawn has increased from a handful in 2004 to an estimated 763 in the 2017-18 season, according to the Russian River Monitoring Program.

By 2020-21, that number dropped back to 214, with adults observed in only eight of the 33 coho streams surveyed, according to the schedule. A similar, although less extreme, reduction was also observed in adult Steelheads.

Federal fisheries managers have set a goal of 10,100 adult coho salmon returning to the Russian River Basin each winter as a baseline for recovery, so there is still a long way to go.

And they look like they face another tough summer in sight, though the mid-April rains offered an unexpected buffer just as conditions seemed to offer little hope.

“It was a close choice,” said Gregg Horton, principal environmental specialist at Sonoma Water. “I mean, if this rain hadn’t happened, it could have been practically a complete loss, or nearly so, of a class of coho smolt.”

Instead, strong streams filled the waterways and reconnected the tributaries with the main stem of the Russian River just in time for the coho smolt migration peak in early May, Horton said.

It might be enough to see year-old fish during their emigration, though latecomers in late June may struggle, he said.

The story is different for the little ones who need to spend the summer feeding and breeding in streams with little humidity deposited in the surrounding landscape to reintegrate them after three extremely dry months at the beginning of the year.

This means that the “young of the year” during the summer – the fish that emerged from gravel nests in March or so – will likely face the same dire conditions as last year and during the past drought.

Field teams will be on hand to rescue those who can. But, Horton said, “it’s not an ideal management strategy.”

“These watersheds have been altered by years of development and various land uses, and they have lost some of their hydrological resilience,” he said. “So the habitat is essentially more fragile and we still have a lot of work to do with the ecosystem to build resilience for a changing climate. The fish rescue is just a short-term effort to try and save the genetic material we have in the landscape right now. “

You can contact staff writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.

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