National Park Service biologists say they have counted the largest number of young coho salmon in Pine Gulch Creek in the Point Reyes National Seashore in more than 20 years — an encouraging sign that the once-thriving, but now endangered fish may be returning to their former stronghold after more than a decade-long absence.
National Park Service biologists reported finding 300 juvenile salmon in the creek this summer, which they said is the largest count since it began regularly monitoring the creek in 2001.
“Those that survive over the summer and through the winter will migrate out to sea next spring as smolts,” park service staff wrote in an update this month. “Hopefully several will return again as adults to keep the coho population alive on Pine Gulch.”
This is the second year in a row that park staff found coho salmon in the creek after they vanished more than a decade ago. The park service says historical accounts indicate the 7-mile creek that follows Highway 1 and flows into the Bolinas Lagoon was one of several salmon strongholds in coastal Marin. By the 1970s, damming, water diversions and the major drought in 1976-77 had extirpated most of the Pine Gulch Creek runs and others throughout the county.
Coho salmon were not found in Pine Gulch Creek again until 2001. However, the population declined between 2006 to 2009 as a result of low numbers and environmental pressures. No more salmon returned after the winter of 2008-2009.
It wasn’t until the winter of 2020-2021 that park biologists came upon the carcass of a coho salmon laying next to its eggs. When they returned again in July, the researchers found baby coho swimming at the same location.
Coho salmon have three-year life cycles. After hatching, the young salmon rear in their freshwater homes for about a year-and-a-half before swimming out to the ocean. After another year-and-a-half, they return to the creek they were born in to spawn and then die. Park staff said it is likely the salmon that spawned in Pine Gulch Creek these past two winters were originally born in Lagunitas Creek or Redwood Creek, but strayed into Pine Gulch.
While park staff said the return of the salmon to Pine Gulch Creek is encouraging, expectations on the long-term viability of this run should be tempered.
“For coho to steadily recolonize Pine Gulch, it would require regional salmonid runs to remain strong, thus increasing the likelihood of more fish straying into this watershed,” staff wrote. “Still, if climate conditions remain conducive for juvenile rearing and high ocean survival, we just might see members of this cohort return to spawn in Pine Gulch again in three years.”
Conditions at Pine Gulch Creek have improved as part of a partnership between local farmers and the Marin Resource Conservation District. Under the program, three Bolinas farms agreed to forgo their summer water diversions from the creek beginning in 2018.
In return, the farmers were given permission to store water in four ponds during the more flush winter months. The extra water in the creek benefits young rearing coho when flows can drop to dangerously low levels in dry years.
“Those fish now have their own water rights,” district executive director Nancy Scolari said. “Our hope is that that is working. It’s encouraging to see there are some numbers coming back.”
Peter Martinelli’s Fresh Run Farm is one of the three participating farmers and said the project has provided mutual benefits to both the fish as well as the fruits and vegetables he grows. Before the project, a dry winter would mean that he likely would not be able to pump water in the summer to irrigate his crops. Martinelli said the ponds now provide a more secure source of water during dry times.
Growing up seeing coho in the creek as a child, Martinelli said he has always wanted to see them come back in robust numbers.
“I’m hoping it’s the foundation of building a run back here,” Martinelli said.
Source: www.mercurynews.com