Endangered baleen whales, including the blue, fin, sei, humpback, and right whales, are distributed worldwide in polar and temperate waters and migrate between warmer waters used for breeding and calving in winter and high-latitude feeding grounds where food is plentiful in the summer. The sperm whale is an open-water species and is found mainly in temperate to tropical waters in both hemispheres. Females generally calve every 2 to 3 years. Most baleen whales feed on a variety of shrimplike invertebrates, and some species also take small schooling fishes and squid. Sperm whales are deep divers and feed mainly on large squid and deepwater fishes.
Blue whales are the largest of all animals.
They usually reach peak abundance off southern California in June and are rarely sighted after October. The blue whale migration pathway through this area generally appears as a broad band along the continental slope west of the Channel Islands. Commercial whaling reduced the blue whale population worldwide from an estimated 228,000 to less than 10,000. Currently, the blue whales that feed off California are believed to number about 2,300, more than recent estimates for the entire North Pacific population. Fin Whales, like blue whales, migrate northward from subtropical calving and wintering grounds to summer feeding grounds in Alaska.