The favorite food of these giants is krill, or shrimp-like euphausiids, that are up to three inches long. Blue whales must eat two to four tons of krill a day during the feeding season. They concentrate on feeding during the polar summers primarily around the Channel Islands, Monterey Bay, and the Farallon Islands/Cordell Bank. During the winter months, they migrate to the warmer waters in Mexico and Costa Rica.
The blue whale was too swift and powerful for the 19th century whalers to hunt, but with the arrival of harpoon cannons, they became a much sought after species for their large amounts of blubber. The killing reached a peak in 1931 when 29,649 blue whales were taken. By 1966, blues were so scarce that the International Whaling Commission declared them protected throughout the world. Today, there are between 8,000-9,000 blue whales in the oceans, and they are considered an endangered species. However, we can see them in the summer and fall off the central California coast, feeding in such places as the Gulf of the Farallones and Cordell Bank National Marine Sanctuaries. The 2,800 blue whales that feed along the California coast make up the largest concentration of blue whales in the world.