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Marin Independent JournalSalmon returning to Marin creeks Monday, November 29, 2004 - Federally
protected coho salmon are slowly but surely making their way back to the
creeks of Marin to spawn with a little help from locals working to
re-establish populations, which have winnowed over the years.
"The overall trend has been an increase in population in coho but there
have been variations from year to year," said Greg Andrew, fisheries
biologist with the Marin Municipal Water District, which manages much of
the Lagunitas Creek watershed. "The best way to describe the coho
population is stable, but tenuous."
In the 1940s, Lagunitas Creek helped contribute to a statewide historic
high of 500,000 coho. At Lagunitas Creek, the largest coho salmon 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
precipitated primarily by a loss of free-flowing creeks and rivers that
have been impacted by development, culverts, dams and other obstacles.
Coho are listed as a threatened species by the federal government and
endangered by the state.
Still, Lagunitas Creek and its tributaries are among the state's prime
coho salmon spawning grounds, and host of groups are working to keep the
species stable.
Counts by the MMWD of redds - gravel nests where fish lay eggs - has
been strong in recent years and efforts to buoy the coho may be part of
the reason, researchers say. The water district spends about $460,000
annually on its fisheries programs.
The water district, for example, has placed logs - which are secured
with wire and boulders - in sections of the creek to create pools. The
pools help protect the fish from rushing waters during heavy storms and
create a place for the coho to thrive during dry summers. The National
Park Service has done similar work in Redwood Creek in West Marin.
"Placing of these woody debris are tiny steps that improve conditions
and each year bring a few more fish," said researcher Jerry Smith, a San
Jose State University professor who teaches fisheries management and
conservation biology. He has studied juvenile coho in Redwood Creek for
the last decade. "Those pools are important during storm years so the fish
and eggs are not swept away."
The coho spawn in the Lagunitas watershed each winter after the
two-foot fish, which weigh up to 12 pounds, leave the ocean and travel
miles up local streams to lay their eggs, riding in on the coattails of
large storms as Marin's creeks swell.
They arrive as red, shimmering fish ready to spawn a new generation.
Spawning continues into January.
Young fry who are born will repeat the same journey, if they are lucky
enough to survive predation, heavy rains, dry summers or any other number
of risks, which are many and sometimes unexpected. Coho have been preyed
on by river otters who are coming up and eating salmon on Lagunitas Creek
the last two years.
The 2- to 6-inch fry emerge in the creek and stay about 18 months, then
head out to the open ocean and spend another 18 months before they come
back to the creeks, spawn and then die - a three-year life cycle.
From his work in Redwood Creek, Smith is optimistic about the future of
the coho.
"All of the classes or coho are doing well and have been able to
rebound from disasters such as heavy rains and dry summers," he said. "But
coho are a very particular species and they don't do well in fluctuating
environments."
And some of the coho environment can never fully be replenished, Smith
noted.
Redwood Creek, for example, is affected as the community of Muir Beach
pulls groundwater that would otherwise end up in the creek, lowering water
levels, Smith said.
Also, a body of water known as the Big Lagoon at the mouth of Redwood
Creek once was a large lake, allowing coho a place to stop and rest,
increasing their chances for survival.
But in the 1950s, the 12-acre fresh water lagoon - which had another 13
acres of surrounding wetlands - started to disappear, choked to death by
fill and levees put in by ranchers so the area could be used for cattle
grazing. Sediment from development and the parking lot at Muir Beach
further damaged the resource. Today, it resembles a meadow, covered with
grasses and trees.
As the lagoon was lost to farming it disappeared, and so did many coho.
The National Park Service now has plans to restore the lagoon.
"It will never be back to what it was, but it will help the fish thrive
in good, wet years and protect them in dry years," Smith said. "All these
things help stabilize the population."
Last week, members of SPAWN - the Salmon Protection and Watershed
Network - were at Roy's Pools along San Geronimo Creek planting willow,
huckleberries and honeysuckles to create shade for the coho.
"These pools were pretty much exposed to sunlight and what that does is
promote the growth of algae and it also dries out the pools," said Paola
Bouley, a SPAWN watershed biologist. "We are here to create a shady
environment."
San Geronimo Creek is a main tributary to Lagunitas Creek.
"These tributaries are really important spawning habitat for salmon,
and before people didn't realize that," said Bouley, as she teetered on
the edge of a culvert, planting a honeysuckle.
SPAWN helps coho in other ways. During the summer they pluck juvenile
coho from drying creeks and get them into wetter areas.
"We have seen a large-scale decline, but it relatively stable now, with
a population of about 500 spawners in the Lagunitas watershed since the
mid-1990s, and it's the largest wild coho run in California," Bouley said.
"Even though it's the largest it is very vulnerable because it is a small
population and very isolated."
The Marin County Resource Conservation District, Trout Unlimited and
others have also been involved in efforts to help save coho as well.
"The main goal is to maintain what we have and to protect what we
have," Bouley said. "It will take a little longer to see the effects of
what we are doing, but these efforts have helped stabilize the
population."
Contact Mark Prado via e-mail at mprado@marinij.com
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