Blue whales are oceanic animals and have been seen in every ocean. In the Northern Hemisphere, distinct populations exist near Iceland, California and in the region between Newfoundland and Greenland. In the Southern Hemisphere, the whales are often sighted in the Antarctic, and near Australia and New Zealand.
Blue whales are the largest living mammals. Their numbers have been greatly reduced by whaling, and hunting of blue whales was banned by the International Whaling Commission in 1966. Experts estimate the current population at between 5,000 and 12,000 individuals. The largest population of blue whales lives off the California coast and is believed to number about 2,800 individuals.