Rare harbour porpoise thrives in Finnish coastal waters, say researchers

A single harbour porpoise has been observed moving actively and appearing healthy in Finland’s Ostrobothnia region this week, providing researchers with a unique opportunity to document its behaviour, reports Yle.

The porpoise, spotted near Vassor in Mustasaari and the mouth of the Kyrönjoki River, has remained in the same area for several days—an unusual pattern, according to marine mammal researcher Markus Ahola of Turku University of Applied Sciences.

“It was fishing very actively on Wednesday morning, close to shore where people could watch it,” Ahola said. “It looked quite healthy and didn’t seem particularly disturbed by the human presence, though it did avoid some boats.”

Researchers collected extensive material for study, including photos, videos, and underwater sound recordings of the porpoise’s echolocation. Ahola described the encounter as the first documented chance in Finland to observe the species’ behaviour in detail.

The porpoise, typically found in the southern Baltic Sea, is not commonly seen in Finland’s brackish coastal waters. While its echolocation should help it navigate the murky conditions, Ahola noted that such detours remain rare. He hopes the animal will soon return to its usual habitat to contribute to the population’s survival.

“Ideally, it will head back now,” Ahola said. “We want it to get enough food for the journey home.”

Harbour porpoises, once more common in Finnish waters until the mid-20th century, are now a protected species. Their small population cannot afford unnecessary losses, researchers warn.