But he admits it's hard to tell just what is going on, particularly on the hot, rugged shores of Baja. By the time a team can identify a mortality and get to it, the warmth of the sun has caused bloating and deterioration in the physiology of the carcass, so good diagnostics really can't be done. Mate says one possibility for the gray whale mortalities might be that they are not getting enough to eat during the summer. The animals spend the summer months in the Bering Sea between Alaska and Siberia. They fatten up there and then fast during the migration south, and they don't eat during the winter or in the spring when they head north again.
Gray whales feed on bottom-dwelling creatures in the Bering Sea.
Researchers have noted huge changes there at all levels of the food chain, and some have theorized that those changes are part of an even larger disruption of ocean temperature and biomass patterns. Mate says those changes might be affecting the amount of food the gray whales can find during the summer and they need a lot of food. Not only do they need to fatten up to get through the months when they don't eat, they also need fuel for the survive a 12,000-mile migration from Alaska to the Baja Peninsula the longest migration of any marine mammal.