A rare right whale spotted off Ireland resurfaces near Boston

In a rare sighting, a critically endangered North Atlantic right whale, first photographed in 2024 off the coast of Ireland, was recently reidentified near Boston, U.S., on Nov. This is the first time a North Atlantic right whale (Eubalaena glacialis) was initially documented in Irish waters; before that, it was unknown to scientists.

The whale then crossed the Atlantic Ocean and was confirmed through a photographic match, some 4,800 kilometers (3,000 miles) away near Boston. “Encounters like this highlight both their [right whales’] resilience and the importance of international cooperation to support their recovery,” Daniel Palacios, director of the right whale ecology program at the nonprofit Center for Coastal Studies (CCS), said in a statement.

Researchers don’t quite know what prompted the whale’s transatlantic journey. “It’s hard to say if they’re looking for food or they’re just exploring,” Amy Warren, a scientific program officer with the New England Aquarium’s Anderson Cabot Center for Ocean Life, told Mongabay in a video call.

Her group helps match photographic identifications for right whales and maintains a catalog of them. Today, an estimated 384 North Atlantic right whales remain, nearly all inhabiting the western North Atlantic. This population historically migrated along the east coast of the U.S. and Canada.

But over the last decade, warming temperatures have pushed the whales farther north, into cooler Canadian waters. Scientists believe there was once a subpopulation of these whales in the eastern Atlantic until whaling extirpated them from European waters. Though the recently spotted whale is the first to be initially discovered in Ireland, it is one of seven that have been documented crossing the Atlantic from Irish waters.

“All the other whales were first seen here in their normal area on the east coast of the U.S. and Canada, already documented in the catalog, then went to Europe and came back. This one, to our knowledge, has never been seen before until it was first seen in Ireland,” Warren said. Warren said other right whales are also known to venture outside the usual migration route.

A whale named Mogul, for instance, was seen off the U.S. coast for several years after his birth, until he was documented in Iceland in 2018, then in France in 2019. A year later, Mogul returned to the U.S. Another female whale “only shows up when she’s pregnant,” Warren said.

The whale comes to the calving grounds to give birth and raise her calf for a few months. Then she travels to parts unknown and disappears for a decade until she is ready to give birth again. North Atlantic right whales are one of the most critically endangered, and well-studied, whale species in the world. But Warren said this unusual sighting shows that “we still have a lot to learn.” Banner image: A right whale photographed off Boston, previously spotted in Ireland in July 2024.

Image courtesy of the Center for Coastal Studies, taken under NOAA permit 25740-03.