California’s ‘iconic’ native fish facing extinction, with climate change a major cause
On a tree-shaded bend in Dutch Bill Creek at Monte Rio, three technicians from the Sonoma County Water Agency huddled on a gravel bar to examine the day’s catch, all in the name of science and a sustained campaign to restore one of California’s most endangered fish.
Retrieving 163 coho salmon smolts, or young fish, from a wooden fish trap set in knee-deep, clear flowing water, the crew bathed the four- to six-inch salmon in a bucket of Alka-Seltzer solution, briefly numbing them for easier handling.
The technicians measured, weighed and counted the year-old, hatchery-bred fish before releasing them to continue a perilous journey to the nearby Russian River and out to the Pacific Ocean.
If the young coho, swimming mostly by night to evade predators, make it to the ocean and grow to adulthood, they may in about 18 months return to the Russian River and be counted once again before they spawn and die.
There’s a lot riding on the coho completing their short, human-assisted life cycle.
Nearly half of California’s native salmon, steelhead and trout - 14 out of 31 species - are facing extinction in 50 years under current conditions, according to a scientific study released last week.
Another nine species are likely to vanish in 100 years unless steps are taken to address threats such as low water flows, pollution, urban growth, dams and degraded habitat, exacerbated by the recent drought and climate change, the 106-page report by the conservation nonprofit California Trout and the UC Davis Center for Watershed Sciences said.
“California’s unique salmon and trout species are on a ?trajectory to extinction,” said Peter Moyle, a co-author of the ?report and UC Davis biologist who has studied California freshwater fish for more than 40 years.
“But extinction is not inevitable,” Moyle said. “Their future is truly in our hands.”
Salmon, trout and their ?relatives, found from one end ?of California to the other, are “the iconic fishes of the Northern Hemisphere,” the report said.
Coho salmon in the Russian River, along with Sacramento River chinook salmon, had the worst survival prospects of the 31 species assessed in the report, “State of the Salmonids II: Fish in Hot Water.”
The two species are “our most imperiled types of salmon,” said Patrick Samuel, a report co-author and Cal Trout conservation program manager.
The report acknowledged a “heroic effort” in Sonoma County to restore coho salmon, which Moyle said were “virtually extirpated” from the Russian River watershed.
A $50 million campaign to revive the coho, steelhead and chinook in the watershed over the past decade has boosted coho spawning numbers from single digits to several hundred a year, but Moyle said the coho population “cannot be regarded yet as self-sustaining.”
Other North Coast fish cited in the report include Russian River steelhead, coho salmon and two species of steelhead in the Eel River, and a chinook salmon species found in both rivers. All but the winter-run steelhead in the Eel are slated for extinction in ?50 to 100 years.
Climate change is the “overarching threat” to all of California’s salmon, steelhead and trout, Samuel said. It was deemed a “critical threat” to ?19 species, capable of pushing them to extinction - in combination with other threats - in as little as 10 years under current conditions, he said.
In California, climate change is likely to increase the proportion of precipitation that falls as rain rather than snow, reducing the amount of cold snowmelt trickling into streams during hot summer months when juvenile salmon and steelhead need it the most to survive during low flows, he said.
Less snow falling over the Eel River watershed headwaters in the Snow Mountain Wilderness would “underscore the issue” of diverting water from the Eel River to the Russian River via the Potter Valley Project, Samuel said.
The project, which delivers water to a small PG&E hydropower plant in Potter Valley and then into Lake Mendocino, is beginning a federal relicensing process that renews conflict between Eel River advocates who want the project shut down versus communities and ranchers from Redwood Valley down to Healdsburg that have depended on the water diversion for nearly a century.
The Potter Valley project is cited in the report as a threat to the chinook salmon in the Eel River because the water diversion “reduces habitat suitability.” The river’s summer-run steelhead are impacted by Scott Dam, which impounds Lake Pillsbury and blocks access to about ?285 square miles of spawning habitat.
The steelhead, deemed vulnerable to extinction by 2050 due to their reliance on summertime cold water flows, are also harmed by illegal water diversions from “exploding marijuana cultivation,” the report said.