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. 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."

"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."

A harbor porpoise surfaced in the Oxbow of the Napa River and remained cruising the same stretch into Monday, with a local reporting two animals the next morning. Historical records show sightings in 2007 and 2015, underscoring the rarity of such inland appearances. The Marine Mammal Center confirmed at least one porpoise and noted the animal did not appear distressed, likely lingering while food is plentiful before returning to San Francisco Bay and the open ocean. Boaters and kayakers were urged to give the animal a wide berth. Porpoises are smaller, quieter, and more elusive than dolphins and their movements often follow the tides.

Read at The Mercury News