This is one in a string of dead whale sightings that have been designated as the 2015 Gulf of Alaska Large Whale Unusual Mortality Event (UME). From May to mid-August, 30 large whales were reported including 11 fin whales, 14 humpback whales, 1 gray whale and 4 other unidentified large cetaceans.
The "unprecedented" warm water in the Pacific caused a massive toxic algae bloom from California to Alaska.