By Maria Grusauskas

For more than 14,000 years, humans have had a close relationship with wild salmon.

Along the Pacific Coast, natives harvested thousands of adult salmon each fall from their spawning grounds in local rivers and streams, a catch that fed their families throughout the year.

While many cultures in the Pacific Northwest and Alaska are still deeply wedded to the salmon resource, California’s grasp has grown increasingly slippery, with only a small percentage of its historical natural breeding population remaining.

Salmon’s legacy for Californians goes far beyond its estimated $1.4 billion fishery or its classification as one of the most nutritious foods in the world: The fish also provide a vital transfer of nutrients and energy from the ocean back to the freshwater ecosystems where they were born.

“People have done studies to show that you can identify ocean-derived nutrients from salmon in many dozens of different species, like kingfishers or water ouzels, fish-eating ducks, foxes, raccoons, coyotes—all the way up to the big predators that used to live here but are gone, like grizzly bears,” says Nate Mantua, a research scientist for the National Oceanic and Atmospheric Administration’s (NOAA) Southwest Fisheries Science Center in Santa Cruz.

Accumulating 95 percent of their biomass at sea, adult Pacific salmon die after they spawn, and their nutrient-rich carcasses, gametes (mature eggs and sperm) and metabolical waste return to the land. “It’s fascinating that, over the eons, a lot of fertilizer was provided by these dead salmon, so a lot of the wine grapes and a lot of the agriculture inland by the rivers was fertilized by salmon for a long time,” says Randy Repass of the Golden Gate Salmon Association (GGSA), a coalition of salmon advocates based in Petaluma.

Salmon’s yearly return props up an entire food web, replenishing bacteria and algae, bugs and small fish, and fueling plant growth with deposits of nitrogen and phosphorus.

“They fertilized forests as well, there are lots of studies that find salmon’s ocean-derived nutrients in trees that grow along productive salmon watersheds,” says Mantua. “And where we’ve depleted the natural runs of salmon, we’ve really degraded that connection.”

Not part of the aforementioned $1.4 billion fishery, but a big concern in Marin County, are the struggling coho salmon, a species of Pacific salmon that are illegal to eat.

The number of endangered coho salmon in Marin might be up this year—269 ‘nests’—but that number doesn’t mean anything without context and an appreciation of the historical baseline, says Todd Steiner, founder and executive director of the Turtle Island Restoration Network in Olema. The organization’s Salmon Protection and Watershed Network (SPAWN) is trying to save the coho from outright extinction in California.

A few years ago, the returning coho numbered 250, Steiner says, but a fully recovered fishery would see some 2,600 adult fish a year returning to Marin creeks to spawn, for a decade. But even that won’t get you to the true historical baseline of the fish, given that about half of the salmon’s habitat in Marin County has been destroyed, Steiner says—and continues to be destroyed, especially in the San Geronimo Valley.

Whereas the fight over saving the salmon in other parts of the drought-stricken state often comes down to agriculture issues versus piscine ones—save the steelheads or water the almonds?—in Marin County, the issue is whether the coho can prevail over new-home development in San Geronimo Valley and West Marin.

Steiner says that his organization, along with local water boards and the National Park Service, has been able to “restore the mistakes we’ve made for 100 years,” by, among other measures, restoring creekside habitats in the Lagunitas Creek watershed. At the same time, Marin County has failed to pass a streamside conservation ordinance that would limit future creekside development. That ordinance has been under consideration for 10 years, Steiner says. “So while we are trying to fix the mistakes of the past, we’re basically making the same mistakes as in the past.”

The Lagunitas watershed, Steiner says, fields the largest coho population in the state, but the coho is an endangered species on the brink of extinction in the state. Steiner explains that the San Geronimo Creek is considered a “sub-watershed” to the Lagunitas watershed, as its creek is a tributary of the Lagunitas watershed. The coho, Steiner says, prefer to lay their eggs in the San Geronimo sub-watershed. And that’s a problem, he says, since that’s “where all the development is happening.”

Last year, SPAWN prevailed in litigation against Marin County and forced it to begin assessing development applications with a cumulative impact analysis. “If you always look at it one house at a time, you never see any impact,” Steiner says. “Now the county is doing the cumulative impact analysis, but simultaneously approving development at the same time. As the fish make their way up the Lagunitas Creek, they’re in protected waters in the Golden Gate National Recreation Area, and then into Samuel P. Taylor State Park. But that’s where it gets dodgy. The fish continue to head upstream “and into the smaller tributaries—and that’s where the habitat has been destroyed.”

The Chinook (aka king), the largest salmon species (adults often exceed 40 pounds and are capable of growing to 120 pounds), is the pride and joy of California’s salmon fishery. Not so long ago, the Central Valley watershed was one of the biggest producers of naturally breeding Chinook salmon in the world, second only to the Columbia River, with the Klamath River another big California contributor. Driven by the Sacramento and San Joaquin river systems, the Central Valley nursed a ballpark average of a few million salmon per year, emerging each spring out of the Sacramento-San Joaquin Delta, says Mantua.

“Today, natural production—maybe in a good year—is in the hundred thousand or hundreds of thousands,” Mantua says. “So, yeah, it’s a few percent of the historical population.”

In addition to cold ocean water and an ample food supply at sea, salmon require cold river water that drains all the way to the sea, and, during their early life, a delta habitat. Salmon eggs do not survive in water warmer than 56 degrees, which is why adult fish ready to spawn instinctively head toward the cold, upper headwaters and tributaries coming out of the snow-packed mountains.

Development in the 1940s through ’60s, and especially the constructions of dams like the Shasta Dam, built in 1943 on the Sacramento River, played a key role in the near annihilation of the long-standing fish stock. “When they built the big dams in California, they basically blocked off access to 80 or 90 percent of the habitat salmon historically used to reproduce in California,” says John McManus, executive director of the GGSA.

California’s four salmon runs—fall, late fall, winter and spring—are named for the time of year the fish return from the open ocean as adults, after about two to five years spent feasting on smaller fish and krill at sea, and back under the Golden Gate Bridge to the Sacramento-San Joaquin Delta. As of 1989, the winter run had joined the ranks of 130 other endangered and threatened marine species when it was listed as an endangered species under the Federal Endangered Species Act. Ten years later, the spring run was listed as threatened.

“When we have a really good fishing year out in the ocean, it’s because of two things,” McManus says. “We have a good contribution from natural spawning salmon coming out of the Central Valley, and we have a good contribution from the hatcheries.”

Following a period of abundance in the late ’80s, and then again in the late ’90s and early 2000s, California’s salmon season was closed in 2008 and 2009, resulting from a population crash that NOAA scientists found was due to a lack of upwelling and the subsequent low production of krill, one of salmon’s dietary staples.

“The population has undergone a modest rebound since then, but it still has not reached the abundance that we observed in the late ’90s and early 2000s,” says Michael O’Farrell, a research fish biologist at the NOAA.

While there has been an increase in small sardines, a potential good sign for salmon, Greg Ambiel, who has been fishing salmon locally for 30 years, is not hedging any bets for this coming season.

“The fish are being killed in the Central Valley before they get a chance to get to the ocean,” Ambiel says. “If you follow the money, that’s who gets the water. It’s simple: Just go look at the almond trees in the Central Valley.”

Indeed, over the last few years, a fairly drastic shift has occurred, with high-profit almond crops replacing raisin grapes and other less profitable crops in the Central Valley. The problem for salmon is that it takes a gallon of water to produce one almond—which is three times more water than it takes to produce a grape—according to a study published in 2011 at the University of Twente in the Netherlands. Water demands for agriculture are a known contributor to an estimated 95 percent loss of salmon’s critical rearing ground in the Sacramento-San Joaquin Delta.

Last month, O’Farrell began the process of calculating 2016 abundance forecasts for both the Sacramento and Klamath rivers and tributaries, based on data that includes the return of fish the previous fall. Each March, he reports the number to the Pacific Fishery Management Council, who then sets the season in April.

“Where we’re at right now, we’ve come out of the very low abundance periods of 2008 and 2009, but we don’t know exactly what the returns are for this past year,” O’Farrell says. “There are some issues that we are monitoring with regard to the effects of drought and ocean conditions. It’s hard to say which way the population’s going to go at this point, but we’ll have more information on that in a couple of months.”

The Central Valley Project Improvement Act, passed in 1992, ambitiously hoped to double the number of salmon and steelhead trout in the Sacramento River basin over the past 22 years, but it has fallen short. While their goal was to see 86,000 spring-run Chinook salmon spawning in the Central Valley by 2012, the number was only 30,522. Federal officials cited obstacles such as drought, competing demands for water and lack of funding.

But Steve Lindley, leader of the Fisheries Ecology Division at the NOAA, points to wetland restoration success stories in the Central Valley, in places like Clear Creek and Butte Creek.

“These shallow areas that are nurseries for salmon—those populations have done very well, even during the poor ocean and drought periods,” he says, “so it’s not a lost cause. But we do really need to address some of these habitat issues, and find a way to operate salmon hatcheries in a way that supports our fisheries without imperiling their long-term liability. We’re really keen on working with GGSA and the fishing community and the broader fish and water communities to try to find those kind of solutions.”

Tom Gogola contributed to this article.