Rare sighting of harbor porpoise recorded in Napa River, experts urge distance

Napans strolling along the river Sunday may have caught a rare sight — a harbor porpoise surfacing in the Oxbow. By Monday, the animal was still cruising the same stretch of water.[

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Local resident Casey Mac filmed the porpoise around 8 p.m. Sunday and said he returned to the riverfront the next morning, where he saw two porpoises circling in the same spot.

“Been 10 years since there was a sighting in the Napa River,” he told The Press Democrat.

Historical records show a harbor porpoise swam several miles up the Napa River in 2007 — one of the first sightings in decades. Another was filmed in 2015, underscoring how rare it is to see the animals this far inland.

Giancarlo Rulli, spokesperson for The Marine Mammal Center in Sausalito, confirmed at least one porpoise had been spotted. A second hasn’t been verified. He said the animal doesn’t appear to be in distress and will likely remain in the area as long as food is plentiful before heading back toward San Francisco Bay and the open ocean.

Rulli urged boaters and kayakers to keep their distance.

“Make sure you’re giving a wide berth, especially if you’re in a waterway, and observe it from a safe distance,” he said.

Though often mistaken for dolphins, porpoises are a separate species. They’re smaller and stockier, with rounded snouts and triangular dorsal fins. Dolphins are sleeker, with longer beaks and curved fins — and unlike dolphins, porpoises are quiet and elusive, surfacing only briefly before slipping back underwater.

Harbor porpoises are regulars in San Francisco Bay and occasionally push farther upstream into tributaries like the Napa and Petaluma rivers, usually in pursuit of fish. Their movements often follow the tides.

Their presence today marks a comeback. The animals vanished from the Bay in the 1930s, likely because of industrial pollution and entanglement in fishing nets, and didn’t return for nearly 60 years. Their reappearance in the early 2000s is considered one of the Bay Area’s quiet conservation success stories, with populations rebounding after tighter gillnet restrictions and marine protections.

Since 2007, The Marine Mammal Center has collected public reports of whale, dolphin and porpoise sightings to help researchers track marine life across the region.