"The Arctic areas are changing," Stafford said. "They are becoming more friendly to sub-Arctic species, and we don't know how that will impact Arctic whales. Will they be competitors for food? Will they be competitors for habitat? Will they be competitors for acoustic space, for instance these humpbacks yapping all the time in the same frequency band that bowheads use to communicate? We just don't know."
The northern seas provide more hospitable habitat for southern species, as the far north warms quicker than the rest of the planet and sea ice retreats.
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"It's not particularly surprising to those of us who work up in the Arctic," Stafford said in a press release. "We are seeing and hearing more species, farther north, more often. And that's a trend that is going to continue. These animals are expanding their range. They're taking advantage of regions in seasons that they may not have previously."
The trend could also be tied to the end of most commercial whaling in the Arctic and northern Pacific Oceans. Russian whaler's ship logs record the sub-Arctic species in the region during the mid-to-late 20th century, according to the abstract of Stafford's presentation. The whales may be returning to previously lost territory.