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Coho, Steelhead Counted As They Head For Open Sea

ONE FISH, TWO FISH: The Salmon Protection and Watershed Network is studying the health and abundance of coho and steelhead heading out to the ocean. From left, biologist Paola Bouley, SPAWN director Todd Steiner and intern Christina David net small fish in the Lagunitas Creek watershed for further study. (IJ photo/Frankie Frost)

For years, the Salmon Protection and Watershed Network has been counting threatened steelhead trout and endangered coho salmon in the Lagunitas Creek watershed, which hosts some of the best breeding grounds for the species in the state.

For the first time, SPAWN, along with the Marin Resource Conservation District, is counting the number of fish leaving Marin’s creeks for the sea, part of the species’ natural life cycle.

“By counting the smolts that are leaving the streams and going out to sea, you can see how well the population has done through its entire life in the stream system,” said Paola Bouley, a watershed biologist for SPAWN, as she stood on a shaded bank along San Geronimo Creek in Lagunitas.

“We want to see how well they survived in, in particular, the winter flows,” she said. “It’s become more clear that winter refuge areas are critical in maintaining and improving the population. We get these big flows and there is not enough structure to protect them from being washed out.”

Last week, volunteers used nets, buckets and traps in San Geronimo Creek to count the fish leaving for Tomales Bay and open sea. They sifted through traps, counting the coho and steelhead. The coho and steelhead look remarkably similar, with the difference in the fin colors. A spotted dorsal fin means it’s a steelhead.

“We want to understand the population of fish here,” said Todd Steiner, SPAWN’s director. “We are trying to figure out where in their life cycle they are getting crunched, so as we do our conservation and restoration work, we can focus our energies on the most important parts. We know how many come up to spawn, but not how many are going back out to the ocean.”

SPAWN counted 493 coho salmon and 86 steelhead smolts between April 21 and June 9 at a spot along San Geronimo Creek near Lagunitas.

One of the larger smolts is held after being caught during a study of salmon leaving the Lagunitas Creek watershed for the open ocean. SPAWN and the Marin Resource Conservation District are checking these populations for the first time. (IJ photo/Frankie Frost)

“This is the first year we have done it, so we have nothing to compare it,” Steiner said. “We do know that many survived the New Year’s Eve storm, so that is good news. How many didn’t survive? We don’t know.”

The Marin Resource Conservation District also looked at fish heading back to sea at two spots in Lagunitas Creek.

“We want to know what happens to the fish during winter,” said Nancy Scolari, executive director of the district, which works with ranchers on protecting and restoring creek areas on private lands. “We want to know where to spend money to improve habitat.”

The adult coho and steelhead spawn in the Lagunitas watershed each winter after the fish leave the ocean and travel miles up local streams to lay their eggs.

Young fry will repeat the same journey, if they are lucky enough to survive predation, heavy rains, dry summers and other risks.
The fry emerge in the creek and stay about 18 months, then head out to the ocean as smolt and spend another 18 months before they come back to the creeks, spawn and die – a three-year life cycle.

In the 1940s, Lagunitas Creek helped contribute to a statewide high of 500,000 coho. At Lagunitas Creek, the largest coho in state history – 22 pounds and 36 inches long – was caught in January 1959.

But today’s salmon population is 1 percent of that – a decline caused primarily by a loss of free-flowing creeks and rivers that have been affected by development, culverts, dams and other obstacles.

“Coho are really on the brink of extinction on the southern part of their range – which is here,” Bouley said. “The general public loves their salmon. People are overjoyed to see them in the creeks. There is sense of pride.

“They are also an indictor of water quality of these creeks, which are arteries that run throughout neighborhoods.”