Marin rain could spur salmon activity

Carefully wading through knee-high water in Lagunitas Creek, salmon researchers recorded the fish and nesting sites they encountered.

While the first coho and chinook salmon were observed at the mouth of the creek last month, rain has been slow to start this season. That has contributed to a gradual arrival of the adult fish to their spawning grounds, researchers said.

“Right now is when the most fish are supposed to run,” Ophelia Macdonald, a watershed aide in the Marin Municipal Water District fisheries department, said on Monday. “After these rains, there’s probably going to be a lot of fish by the end of the week.”

To date, 53 coho redds, or nests, have been found by Macdonald and water district researchers. A majority were discovered just before rain fell over the weekend, according to the district. The storm brought more than an inch of rain to several Marin communities and more is expected through Thursday morning.

Surveyors also found 12 chinook redds and 13 unclassified redds.

Despite the below-average start to the rain season, it’s still better than three years ago, said Eric Ettlinger, aquatic ecologist for the district.

“We’re looking forward to a lot of fish this year,” Ettlinger said. “We’re expecting an average number of coho salmon to return to Lagunitas Creek.”

He said the average is around 300 to 400 fish, less than historic numbers, but good for today given the endangered status of the fish.

Marin County has the largest population of wild endangered coho salmon from Monterey Bay to the Mendocino County-Sonoma County line. Once believed to have numbered in the thousands, coho populations dwindled to the hundreds during the 20th century because the construction of dams blocked miles of former spawning grounds and tributaries.

Coho salmon generally have three-year life cycles. After hatching, the fry rear in freshwater for about 18 months before heading to the ocean as smolts. After another year and a half, they return as adults to the same creeks and streams where they were born to spawn and then die.

In San Geronimo Creek and other tributaries to Lagunitas Creek, surveyors with the nonprofit Salmon Protection and Watershed Network, or SPAWN, haven’t seen any salmon activity yet this season.

“Our surveys are in the upper tributaries, the highest points in the system,” said Ayano Hayes, a SPAWN watershed biologist. “There hasn’t been enough rain, until hopefully this rain, to allow access and bring more fish upstream.”

Only one coho has been spotted in Pine Gulch Creek in Olema this season, said National Park Service fisheries biologist Michael Reichmuth.

“We anticipate things really kicking off with these storms,” Reichmuth said.

Last year, fish biologists were worried about the lingering effects that the drought has had on salmon populations in Marin County, Reichmuth said. In concert with the California Department of Fish and Wildlife, the National Park Service decided it was best to intervene, he said.

Last week, park staff released 50 adult salmon from the Warm Springs Fish Hatchery, in the foothills of Sonoma County, into Redwood Creek, Reichmuth said.

“We wanted to get them in right before the storms so they can start looking for their natural pairing in the creek,” Reichmuth said. “When the rain comes, it puts them in a good position to shoot upstream and start spawning.”

The park service has also partnered with the Marin Municipal Water District on a project to install antennas throughout the county’s streams.

Ettlinger said researchers have installed four antennas, with the most recent device being placed in Olema two weeks ago.

Researchers tag juvenile fish with microchips. When those fish return, if they swim over one of the antenna ranges, the device records them. This enables researchers to determine how many fish they tagged have survived and returned to their spawning grounds.

“Surveying gives a lot of information about the challenges our fish have, and we use that to guide our habitat restoration work,” Ettlinger said.

The water district is gearing up for one of the largest efforts to restore endangered coho salmon habitat in Lagunitas Creek. The district received a $4.6 million state grant to kick off the work.

The project, which has an estimated cost of $10 million to $12 million, is set to begin next summer. The district plans to use both proven and new strategies to mimic the natural habitats found in the creek before the construction of dams, the agency said.

The project team is expected to return to the board of directors in February to request authorization to solicit contract bidders to do the work, Jonathan Koehler, the district fisheries program manager, said during a project update last week.

“I’m proud of our stewardship of this land,” board member Jed Smith said at the Dec. 12 meeting. “And it’s a unique thing for a water agency to be focused on, and we’re doing it well.”