Coho Salmon Crisis in the Central California Coast ESU

A watershed-related issue examined by the ENVS 560/L Watershed Systems class at CSUMB.

Summary

Marin County's Lagunitas Creek Watershed, once held out as a statewide model for fisheries restoration, is now hanging in the balance with an unprecedented 90% decline in coho salmon returning to spawn so far this year. Fisheries and watershed biologists say that several years of exceptionally reduced winter rainfall have contributed to the worst coho salmon return in recorded history. The decreased rainfall translates as reduced creek flow which prevents salmon from effectively swimming upstream and being more vulnerable to predation in the open ocean.

This unprecedented decline is particularly relevant because the Lagunitas Creek Watershed is considered one of California's most critical ecosystems for endangered coho salmon. Historically the Lagunitas Creek Watershed has been California's largest wild salmon run left, supporting approximately 10% of the state's Coho Salmon population. This local salmon population decline is consistent with recent state-wide salmon numbers plummeting as seen with the closure of chinook salmon fishing along the west coast.

Threat of extinction

"The Lagunitas population is critical to the viability of the entire central California coho population. It is the keystone watershed along the coast," Bouley said. "Fisheries agencies look to Lagunitas as the key to the recovery for neighboring watersheds. We won't have any streams left to seed them if this one is gone."

The watershed is unique in that the primary spawning grounds are in the middle of developed communities. Since coho were listed as endangered in 2005 under the Endangered Species Act, many residents have taken a proprietary interest in the fish. Schools have become involved, organizing work parties and teaching children about the historic coho migration.

More than a century ago, about 6,000 coho spawned in the system of streams every year. At that time, the salmon swam from Tomales Bay virtually to the top of Mount Tamalpais, spawning in tributaries all along the way. But industry started taking a toll almost from the day Joseph Warren Revere spotted the valley in 1846 and saw "a copious stream, fed by mountain brooks."

The redwood forests surrounding the creek were logged between 1860 and 1900. Subsequent homes and roads built along the waterway removed about 60 percent of the original riparian habitat.

The first major dam, which created Lake Lagunitas, was built in 1873. Six more dams were constructed over the next century, the largest being Peter's Dam at Kent Lake, finished in 1953 and then raised 42 feet in 1982. The dams blocked 50 percent of the historic salmon habitat, reduced the amount of gravel and increased sedimentation in the creeks.

But the decline was slow. Old-timers told how they used to spear fish from decks or garage hatches overlooking the creek. In 1959, when the habitat was already in serious decline, the largest recorded coho in state history, a 22-pounder, was fished out of Lagunitas Creek. Lobbying the county

The restoration effort began in the early 1980s when a group called Trout Unlimited began lobbying the county to stop the decline of the fishery.

SPAWN, which was created in 1996, sponsors salmon-watching creek walks during spawning season and has saved more than 15,000 juvenile salmon and steelhead from drying pools during the summer. The Marin Municipal Water District, which is required by the state to help the coho as mitigation for raising Peter's Dam, started counting coho redds in the early 1990s and now works with SPAWN to monitor releases from the dam, install woody debris in the creeks and replant vegetation.

"This is the beacon of hope for the California watershed," Bouley said, but "the fish are missing. They are gone."

E-mail Peter Fimrite at pfimrite@sfchronicle.com..

Location

Lagunita Creek Watershed winds through San Geronimo Valley on the northwest side of Mount Tamalpaisis in Marin County, California.

Resource/s at stake

Fishery biologists fear that the endangered Coho Salmon are threatened with spawning failure and possible extinction for the year. biologically speaking, diminished population size can negatively effect the genetic diversity of the population and thus reduce fitness or viability for the future. Economically, reduced salmon numbers can result in a significant negative financial impact on human communities that have relied on salmon fishing for income and tourism.

Stakeholders

Salmon Protection and Watershed Network, or SPAWN....Who are the stakeholders in the watershed? e.g. agencies, non-profits, associations... National Marine Fisheries biologist

Laws, policies, & regulations

...What laws, policies, and/or regulations are involved?... The CFG, National Marine Fisheries

Systems

... What elements of the biophysical system are/were involved?...

Science

...What scientific studies are or would be relevant / already completed?...

Tools

...What analytical (e.g. modeling) tools were or could be used?...

Future research

...What knowledge gaps remain?...

...Suggest a CWSP MS thesis topic that could contribute to the issue...

...Suggest a topic for a hypothetical study that had unlimited resources...

References

...Proust, M. 1901. Poetica nausea. J. Nauseum. pp 1-9999.

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.