status: Vulnerable, IUCN Endangered, ESA
Description and biology
The humpback whale is most known for its acrobatic leaps and for its distinctive pattern of sounds, called songs. An average humpback whale has a head and body length of 42 to 52 feet (13 to 16 meters) and weighs between 30 and 60 tons (27 and 54 metric tons). Its winglike pectoral (chest or side) fins measure 13 to 16 feet (4 to 5 meters) long. While the whale's upper body is dark gray, its underparts are lighter. White patterns mark the pectoral fins. Despite the animal's large size, it is able to breach (leap out of the water) and perform spectacular spins.
The diet of humpback whales includes herring, pink salmon, Arctic cod, certain mollusks, krill (small, shrimplike shellfish), and other small fishes. Those humpback whales inhabiting Antarctic waters feed primarily on krill. The whales have brushlike plates of baleen (whalebone) lining the roofs of their mouths. Their narrow throats are lined with furrows (called
ventral grooves). To feed, the whales suck in large amounts of water, and the furrows allow their throats to expand like a pouch. The animals then expel the water through their baleen plates, straining out any food.
Large schools of humpback whales form when they migrate between cold and warm waters. Humpback whales inhabiting the waters of the Northern Hemisphere mate between October and March; those in the Southern Hemisphere mate between April and September. A female humpback whale gives birth to a single calf after a gestation (pregnancy) period of about one year. The calf nurses for about one year afterward.
Although scientists are not sure why, male humpback whales emit their haunting song during the mating season. All males in the same group "sing" the same song, composed of moans, cries, grunts, snores, and chirps. Scientists began recording humpback whale songs in the early 1950s. They have found that the songs change each year and no two songs have ever been the same.
Habitat and current distribution
Humpback whales are found in all oceans on Earth from the Arctic to the Antarctic. They feed in colder waters during spring, summer, and autumn. In winter, they migrate to warmer waters near the equator, swimming in deep water along coastlines. Scientists estimate that 25,000 humpback whales currently exist.
History and conservation measures
About 150,000 humpback whales probably existed worldwide when large-scale whaling (whale hunting) began in the seventeenth century. Whales have been hunted for their oil, which is extracted from their blubber and other body parts. Whale oil was originally used in oil lamps. Today, it is used in soap-making, as a dressing for leather, and as a lubricant. Over the centuries, many carvings and items of jewelry—called scrimshaw—have been made from baleen.
With improved hunting techniques in the nineteenth century (including the development of the exploding-head harpoon), the number of humpback whales quickly declined. By the early twentieth century, the population of whales in the North Atlantic had been depleted. Whalers then began hunting those whales inhabiting the Pacific Ocean and the waters of the Southern Hemisphere.
The International Whaling Commission (IWC; body that regulates most of the world's whaling activity) banned the hunting of humpback whales in 1963. However, some nations disregard the decrees of the IWC and the hunting of protected whales continues. Because humpback whales travel close to shore, they are also threatened by shoreline pollution, boat traffic, and fishing nets.