Karen Dunmall, a biologist with Fisheries and Oceans Canada, said pink salmon normally prefer warmer waters than the Arctic has been able to provide. But with the Arctic warming at up to three times the rate of the rest of the world, its waters are becoming more approachable for newcomers like this species.

“Dramatic”, says researcher Henrik H. Berntsen. The Norwegian Environment Agency has launched a major offensive to get rid of the invasive species. But, despite more fishing, there appear to be ever more humpback salmon arriving in Norwegian rivers. Currently, around 70,000 pink salmon have been caught in Norwegian watercourses this year.

Scientists looking at salmon found in Arctic waters are still asking northern harvesters and fishers to submit any unusual catches in exchange for compensation. It's part of the Arctic Salmon Project, which is a collaborative effort involving Fisheries and Oceans Canada, scientists from the South and local hunters and trappers organizations.

“Our results suggest that warming is both increasing freshwater habitat and improving early marine survival of pink salmon in the northern Bering Sea,” said Ed Farley, NOAA Fisheries biologist at the Alaska Fisheries Science Center, who led the study.

The Arctic Salmon Project collected 2,400 samples from the western Arctic this year — more than the past 20 years combined.

Salmon used to be infrequent visitors to the Mackenzie River and communities of the Arctic, but more species have begun to show up in the North more often and in greater numbers than ever before.