(Shutterstock)

(Shutterstock)

The Battle Upstream

Environmentalists work to preserve Chinook habitat

Back Web Only Dec 28, 2015 By Alastair Bland

On the Yolo Bypass, just northwest of Sacramento, scientists and state and federal agencies are collaborating on a plan they hope could save California’s wild salmon.

Currently, the fish are on a path toward extinction. The basic river habitat and water conditions the fish need to lay and fertilize their eggs — and then swim safely to the ocean to become adults — have been almost eliminated by dams and river engineering. Salmon persist at fish-able numbers in California mostly because of the support of hatcheries, which produce millions of juveniles each year and release them into the wild.

But the Yolo Bypass project aims to restore the critical rearing habitat that wild salmon, born in the gravel beds of Central Valley rivers, depend on in their first months of life. The plan is to cut a notch in a key levee about 30 miles northwest of Sacramento and let water spill into a vast sprawl of seasonal farmland that historically flooded every year. There would be plenty for small fish to eat on this floodplain, allowing the salmon to grow larger and stronger more rapidly than if they had remained in the main river channel.

And since the Yolo Bypass eventually connects to the Sacramento River at the west edge of the delta, it would allow migrating salmon to reach saltwater without passing near the dangerous Delta irrigation pumps that kill millions of small fish every year.

The effort, and a few other floodplain projects like it, represents a new direction forward in a conservation arena that has previously focused almost solely on maintaining spawning habitat for the adult fish.

However, it isn’t certain projects like this will be enough to save California’s Chinook.   

Robert Lackey, a professor of fisheries and wildlife at Oregon State University, predicts wild salmon south of Canada will be essentially extinct by the year 2100. A few fish may remain, Lackey thinks, but they will be what he calls “boutique” runs — populations that number in the hundreds or less, are much too small to support a fishery, and draw crowds of tourists each time the fish arrive in freshwater to spawn.

“You’ve probably got a doubling of the human population in the Central Valley and a demand for water that’s probably going to increase,” Lackey says, adding that climate change will probably make Central Valley rivers intolerably warm for most native fish. “I don’t see any way to restore wild salmon because there is almost no habitat left.”

In fact, much habitat still does exist. The problem is that the fish are unable to reach it because of dams — something scientists are now addressing. Upstream of Shasta Dam, biologists have identified long stretches of the McCloud River where salmon, if they could only get there, could spawn in cold, healthy flows of water. The National Marine Fisheries Service is now drafting a plan to reintroduce endangered winter-run Chinook — currently at extreme risk of extinction — to the McCloud, which has been off limits to migrating salmon since Shasta Dam was built in the 1940s.  

Because the McCloud is fed by springs on Mount Shasta, its waters remain cold even through multi-year droughts in which most snowpack vanishes. To get the fish into this river would involve a labor-intensive system of capturing adult winter-run Chinook, then driving them upstream and around the dam.

“But the hardest part would be collecting the young fish again,” says Maria Rea, a regional administrator with NMFS. She says it would be critical to capture them before they enter Lake Shasta, where the small salmon would almost certainly be eaten by black bass and catfish, and release them into the river below to continue their downstream migration.

But this project wouldn’t solve perhaps the most serious issue affecting Central Valley salmon. More than 95 percent of Chinook born in the river system die as they attempt to swim downstream toward the ocean, through gauntlets of predators and water pumps. They fare so poorly because the shallow water wetland habitat that once fringed most rivers and which the fish depended on has been destroyed — mostly cut off from moving waters by levees.

“Tens of millions of fish emerge from Sacramento Valley gravels every year, born into a river system where they have little to eat and the altered environment stacks the cards against them,” says Jacob Katz, a California Trout biologist who is leading the Yolo Bypass restoration. 

That project could be completed this winter, he says, and will restore at least part of the river ecosystem to a state more hospitable to salmon.

But alone, it will not be enough, says Carson Jeffres, a biologist at UC Davis’s Center for Watershed Sciences.

“The Yolo Bypass really just represents the lower 20 percent of the river system,” says Jeffres, who is collaborating with Katz. Jeffres wants to see side channel habitat and floodplains reconnected to the Sacramento River along almost every mile of it as far upstream as Redding. That, Jeffres explains, would give young salmon a safe migration corridor taking them almost all the way to the sea.  

Salmon once were the most important marine food source along the West Coast of North America. The fish were like weeds, spilling from the ocean into nearly every waterway they could physically access. People caught and ate tens of millions of the fish each year, and still the fish returned. In the past 150 years, the fish have dwindled across much of their range. In California, Chinook salmon have disappeared — in large part because of the impacts of gold mining, dams and agricultural water diversions.

In the past two years, high river temperatures have been a major killer, destroying at least 95 percent of the young winter-run Chinook born in 2014 and 2015. The winter-run salmon are particularly vulnerable to adverse water conditions and climate change because the fish spawn in the summer — precisely when air temperatures in the Central Valley soar into the 90s and 100s for months on end. Historically, the fish laid their eggs in the icy year-round flows of mountain tributaries; now, the salmon rely on cold outflow from Shasta Dam — not a consistently dependable source.

“I honestly have low expectations for the winter-run salmon,” Jeffres says. He adds that the McCloud reintroduction plan could prove too labor intensive to be maintained in perpetuity.

But since the other genetically distinct runs of Chinook — and especially the fall- and late-fall runs — historically spawn as the rainy season begins and as temperatures fall, they are better candidates for surviving into a drier, warmer future.

Jeffres and Katz both agree that spawning habitat is not the limiting factor currently impeding salmon recovery.

“The problem is that we have almost no survival in the river,” Jeffres says.

Katz says that “reconnecting floodplains and restoring side channels and other off-channel habitats will result in an immediate response in Central Valley salmon populations.”

He and Jeffres dream that the Central Valley river system, interrupted though it is by dams, may one day be capable again of supporting spawning runs of hundreds of thousands of these salmon – fish that carry out their life cycles unassisted by humans.

Lackey believes reintroduction and habitat enhancement projects, including floodplain restoration, will ultimately be overcome by the effects of climate change.

“We’re going back to 300 years of warm weather like we had in the Medieval Warm Period,” he said. This will shift the natural distribution of salmon northward, he says – and the salmon of California, since they live at the southern end of the species’ geographical range, will be first to go, he says.

U.C. Davis professor of fisheries Peter Moyle published an article in 2013 in the journal PLOS ONE in which he predicted that 82 percent of 121 native California fish species, including several strains of Chinook and Coho salmon, could be extinct by 2100.

Chuck Cappotto, a retired commercial salmon fisherman in coastal Sonoma County, believes in a happier future.

“I don’t think the die is cast yet,” he says. “I think there are things we can do if we had politicians who would stand up for the preservation of salmon.”

More water, Cappotto says, must be left in rivers — even if that means that developers and farmers make financial sacrifices.  

“The idea of losing salmon, of them becoming a museum item, is ludicrous,” he says. “They are so resilient. If you give salmon just half a chance, they will survive, and if we allow them to disappear because of development or lack of action, we should be ashamed of ourselves as human beings.”

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