After 100 Years, A Long Lost Animal Has Returned To The SMC Coast

PESCADERO, CA — A wildlife camera has captured a North American river otter at a protected preserve on the San Mateo Coast, marking the first documented sighting of the species on the Pacific-facing side of the San Francisco Peninsula since the 1800s, conservationists said.

Independent researcher Ken Hickman recorded the otter at Cloverdale Ranch Open Space Preserve, a closed area managed by the Midpeninsula Regional Open Space District. The discovery surprised researchers because river otters have not been documented along the coast there for more than a century.

“Checking wildlife cameras can be like Christmas, but river otters haven't been known to occur on the San Mateo Coast since the 1800s,” Hickman said. “So I knew Midpen and State Parks biologists would be as surprised and interested as I was to see the photos.”

River otters historically ranged along the West Coast from Alaska to Santa Barbara County, but the 19th-century fur trade and pollution devastated populations and reduced their range. In recent decades, populations have rebounded in some areas north of the Golden Gate, with occasional sightings in San Francisco Bay wetlands, officials said.

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The sighting may also signal improving habitat conditions. River otters depend on clean water and abundant food, making them an indicator of the health of aquatic ecosystems, according to researchers.

“River otters can serve as vital bioindicators,” said Midpen biologist Matt Sharp Chaney. He said the sighting and the species’ return to historic habitat offer evidence of recovery in protected landscapes that also support coho salmon and steelhead trout.

Before Midpen began managing the preserve, the San Mateo County Resource Conservation District and Peninsula Open Space Trust completed in-stream pond and floodplain restoration projects.

Megan Isadore, executive director of the River Otter Ecology Project, said the sighting could mark another step in the species’ recovery across the Bay Area.

“If river otters are beginning to repopulate the San Mateo Coast, this marks another step in their recovery after going missing from much of the Bay Area in the early 1900s,” Isadore said. “This discovery suggests that what we have long expected is happening: river otters are making their way to excellent habitat along the San Mateo Coast.”

The nonprofit encourages the public to report river otter sightings through its Otter Spotter community science program, which collects observations to help inform habitat management and conservation efforts.