The loss of Arctic sea ice is predicted to open up the Northwest Passage (the vast northern sea lanes above Canada presently choked off by ice), shortening shipping routes and facilitating the exchange of marine organisms between the Atlantic and the Pacific oceans. Skeletons, DNA samples and harpoon heads have all suggested that bowhead populations living on each side of the continent did meet and mingle in the past. Previous satellite tracking has demonstrated that bowhead whales from West Greenland and Alaska enter the ice-infested channels of the Canadian High Arctic during summer. In August 2010, two bowhead whales from West Greenland and Alaska entered the Northwest Passage from opposite directions and spent approximately 10 days in the same area, documenting overlap between the two populations.