Coho spawning season is in full swing. That means fisheries biologists are donning waders and venturing into freshwater rivers and streams to see how many anadromous fish have come home from the open ocean. On the South Fork of the Noyo River, at Camp 1 in the Jackson Demonstration State Forest, state agencies, the UC Cooperative Extension, California Conservation Corps members, and nonprofit conservation organizations have been counting adult fish and their redds, or nests, since 2009. On Saturday, a couple dozen visitors took a field trip to the site to learn about the life cycle stages of the iconic species.
Dave Wright is a retired fisheries biologist who used to work for the Nature Conservancy. Fifteen years ago, he and a colleague, Sean Gallagher, developed the survey protocol that’s still in use today. “We were two fish biologists that were also surfers,” he recalled, as a large female coho salmon churned the nearby river bottom with her tail. “It was really important, from a recovery perspective, to know how many fish you had,” he continued. “And whether these creeks are responding to your recovery efforts. Are they going away? Are we making more fish? We had no idea. You could have told me there were 30 fish in the Noyo, or 300, or 30,000, and I would have just put up my hands because there was no way to know, other than just coming out and looking at the creek…We kind of developed the statistical analysis of it for this region, but we didn’t invent spawning surveys.”
In the stream across the meadow from a covered row of picnic tables, a small dam forces the fish to swim through a weir in a little bunker that used to be an egg collecting station in the hatchery days. Every two weeks, biologists from the California Department of Fish and Wildlife, or CDFW and the Pacific States Marine Fisheries Commission count the adults, mark them, and extrapolate how many fish are in the river.
Sarah Gallagher is a senior environmental scientist with CDFW. Her husband is Wright’s former colleague. She stood in a light rain on Saturday and talked about the season. “Right now, we’re in the main run of coho salmon,” which have been spawning in the Noyo since November, she reported. “The outlook is pretty good in a lot of our watersheds. It’s a stronger year class. Three years ago, we had a pretty good population…We’re seeing pretty good numbers, so we’re pleased about that. We’ve had a good rainfall, so that means that they have lots of places to get up to their spawning habitats. So far, so good.” One of the crew members just spotted the first steelhead of the year, which will start spawning in January or February, and finish in May. The coho will finish their spawning next month.
While neither species is anywhere near the recovery target set by NOAA, the National Oceanic and Atmospheric Administration, their numbers have remained stable throughout the years they’ve been monitored. Last year, 800 steelhead and 1200 coho came back to the Noyo. The target numbers are 4,000 for coho and 3400 for steelhead. “The trend was in decline when we started,” Wright noted. “And at least it’s not in decline now. That’s the real positive thing that I can say. And that may actually be a very big deal.”
Gallagher and Wright say that cooperative timber companies are ideal partners for conservation efforts, because it’s difficult to manage large sections of habitat with multiple owners who are developing the land and using the water. They say the large local timber companies have biologists on staff who work with CDFW.
The data from the monitoring program on the Noyo is used to prioritize conservation projects like repairing culverts that block fish passage and addressing sediment from a network of roads that were carved into the landscape during 150 years of industrial logging. Another ongoing project is replacing large woody debris in the waterway to slow down the flow, create pools, and provide cover for fish. This mitigates the “bowling alley effect” that was created in the 1970s, when management practices included removing wood from the rivers.
Wright offered a description of the spawning female as a small breakout group of field trippers looked down into the water. “She’s actively scouring out the bottom substrate,” he narrated. “She’s sort of at the tail end of a pool, which is where they typically do this, and she’s found the right-sized cobbles that she can push around with her tail.” The tail was whitened, partly from scraping the gravel, “But also, when the fish come up to spawn, they shut down all of their other metabolic systems. Their digestive system shrinks, and basically their immune system shuts off.” The spawned salmon are called kelts, and because they are so depleted, they are susceptible to fungal infections. “After she lays her eggs, that’ll progress, and she will die. She will be covered with that stuff,” Wright predicted. “They look like zombies. She’ll spend her last days guarding her nest, and she’ll look progressively more white like that. Sort of like me,” he laughed.
At another stop, Gallagher explained how the decomposing carcass of a small jack, or male fish, illustrated another success. The survey includes a carcass count, to document the life cycle of the returning salmon. This one bore signs of having been marked and counted at the former egg-taking station as it swam into the stream. “It’s still intact, so I don’t think something ate it,” Gallagher said. “It has all this wear on it, so it’s been fighting with other males, it’s been rubbing its belly on the ground with females,” presumably while fertilizing eggs. Because the different year classes have different parents, the smaller, wilier males bring genetic diversity to the next year class, in spite of the larger males’ attempts to dominate the breeding season. Even though this male is small, and his tail was worn down, which is typical for females, Gallagher determined its sex by the kype, or extended lower jaw, and its red color. She verified her identification by slitting open the belly of the carcass to reveal its gonads, but there are also much more refined ways to obtain information about returning salmon. There is a hard bony structure in the animal’s skull that accumulates layers of chemicals like tree rings. With enough baseline genetic data, it’s possible to determine which stream each fish and its parents came from, and how long it spent in the ocean and freshwater environments.
Two elementary school-aged children who accompanied their parents for the educational opportunity weren’t sure if they were horrified or delighted by the transfer of nutrients from the ocean to the forest floor. Observing a caddisfly and possible signs of bite marks on the diminished tail, one young visitor exclaimed, “Animals were eating it when it was dead!”
“That is exactly right,” Gallagher confirmed, as another adult chimed in, “Salmon feed the whole forest when they come back.”
“They bring all these really good nutrients from the ocean,” Gallagher concluded. “Because they’ve been feeding out there for a long time.”
