[http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2012/02/03/MNLT1N1KQ4.DTL]
The storied silver salmon of West Marin - long considered a bellwether of salmon health in California - are laying eggs and carrying on in Lagunitas Creek this week almost as if they weren't teetering on the edge of doom.
There are, of course, plenty of obstacles to the species' long-term survival, but last month's long-awaited rain - paltry as it was - prompted the endangered fish to begin their annual rush into the creeks and tributaries of the lush San Geronimo Valley to make babies.
The late blitz of coho brought renewed hope to fisheries experts, watershed managers and the creekside communities where the celebrated fish lay their eggs and then die.
"It shows that these fish can survive for months without spawning, while waiting for the rains to come," said Eric Ettlinger, the aquatic ecologist for the Marin Municipal Water District, which conducts annual fish surveys with help from volunteers and nonprofit groups. "Three years ago people were discussing how coho were about to become extinct in Central California, and it seems like they are beginning to bounce back."
Strong turnout -
Biologists have observed 377 coho salmon in the Lagunitas watershed this winter and 103 redds, the word used by brainy types in smocks to refer to the clusters of pink eggs that salmon lay in the gravel.
It is a remarkable showing, Ettlinger said, considering the lack of rain this season. The salmon, he said, have been waiting since November for creek flows to be strong enough for them to swim up to their favored nesting spots. The carnal surge began Jan. 19, when the region was doused by 10 inches of rain.
Coho, also known as silver salmon, are born in cold freshwater rivers and streams where they live for a year before swimming to the ocean. They typically return at age 3 to where they were born to lay eggs and fertilize them.
This year's fish are the children of the 2008-09 generation, which holds the record for the least fertile since the district began the surveys 17 years ago. Only 43 coho and 26 egg nests were seen in the watershed that year.
"The fish that are spawning now are the offspring of those few fish," Ettlinger said. "We are very pleasantly surprised at how many of those offspring have returned."
Last winter, 152 coho and 80 redds were counted in the watershed, which includes Lagunitas and San Geronimo creeks. That was disappointing, Ettlinger said, because the fish were the grandchildren of the coho that spawned in 2004-05, the most potent generation on record. The 1,342 coho seen in the watershed that year made 496 redds.
Fearing for the fish -
In fact, the past three years were the least profligate spawning years on record, raising fears among biologists that the species was in the midst of a death spiral.
"Last year marked two generations of steep declines," Ettlinger said. "Those years were all lower than their parent generations were. Now, for the first time in seven years, we are seeing more offspring than the parent's generation."
The Lagunitas coho swim 33 miles through the redwood- and oak-studded valley on the northwest side of Mount Tamalpais. It is the largest wild run of coho salmon along the area that biologists and regulators categorize as the Central Coast and is a model for fisheries restoration in the state.
Marin County has always been a stronghold for coho, which were so numerous that grizzly bears fed on them before Europeans arrived in California. Legend has it that homesteaders speared them from docks over the water. The runs kept up even after 1873, when the first of seven dams were built in the watershed, blocking 50 percent of the historic spawning habitat.
Then, suddenly, the fish stopped showing up. Central California coho were listed as endangered in 2005 under the U.S. Endangered Species Act.
The Lagunitas run is unique not only because all the fish are wild - a large proportion of the coho in other places are raised in hatcheries - but because their primary spawning grounds are in the middle of developed communities. Some 40 percent of the coho in the watershed are hatched in tributaries surrounded by homes, golf courses, roads and horse corrals in the 9-square-mile San Geronimo Valley.
The jacks come home -
Ettlinger said there are signs that things are improving. Biologists have spotted a lot of jacks, the small male salmon that return to their natal streams one year earlier than their siblings.
The number of jacks in any given stream is a good indicator of how many fish will return the next year.
"Just last week more than half of the salmon we saw were jacks," he said. "This suggests that there are many, many more of their siblings out in the ocean that will, hopefully, return next year."
Ettlinger said the virility of the salmon this winter despite the difficult circumstances "speaks to the resilience of the species that they can withstand fairly adverse conditions."
He said their survival is also a testament to the dedication of local citizens, schools and community leaders.
"This watershed has a really active volunteer community that does restoration work and creek hikes," he said. "There is a lot of support for the salmon within the watershed."
Coho salmon (Oncorhynchus kisutch) -
(Sources: Marin Municipal Water District, National Marine Fisheries Service, ESRI, GDT and Alaska Department of Fish and Game)
* Range: Coho are found on both sides of the North Pacific Ocean from Hokkaido, Japan, and eastern Russia, around the Bering Sea to mainland Alaska, and south all the way to Monterey Bay.
* Description: Adults typically weigh 8 to 12 pounds and are 18 to 30 inches long, though individuals weighing 31 pounds have been caught.
* Life cycle: Anadromous, meaning adults re-enter natal freshwater streams to spawn after spending half of their three-year life cycle in the salty Pacific. Adults die within two weeks of spawning. Fry grow to 4 to 5 inches long before heading to the Pacific.
Seeing salmon -
The best coho viewing areas in the Lagunitas Creek watershed:
* Leo T. Cronin salmon viewing area: Just off Sir Francis Drake Boulevard where the Shafter Bridge goes over Lagunitas Creek near Samuel P. Taylor State Park. Fish can also be seen from the Shafter Bridge at the Inkwells, a series of small waterfalls along San Geronimo Creek.
* Roy's Pools: Salmon demonstrate their jumping skills in three pools below the former dam site, on San Geronimo Valley Drive, 5 miles west of Fairfax.
* Samuel P. Taylor State Park campground: Coho like to lay their eggs behind the park headquarters building, just off Sir Francis Drake Boulevard.
Eric Ettlinger (right), an aquatic ecologist with the Marin Municipal Water District, and Ben Schleifer wade in Lagunitas Creek to do the yearly coho salmon count. Photo: Sarah Rice / Special to The Chronicle
A male coho salmon swims in Lagunitas Creek. Photo: Sarah Rice / Special to The Chronicle
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