Humpback whale

Name and taxonomy

Mathurin Jacques Brisson listed the animal in 1756 as the whale of New England, because sailors met it often off that coast. Georg Heinrich Borowski turned that name into Latin in 1781 as Balaena novaeangliae. John Edward Gray set up the genus Megaptera in 1846, and Remington Kellogg restored Borowski's species name in 1932. Megaptera comes from Greek words for giant and wing, a reference to the flippers. The common name describes the way the back arches as the whale rolls into a dive.

A 2014 genetic study found that the whales of the North Atlantic, North Pacific and Southern Ocean mix little. It proposed one subspecies for each ocean: novaeangliae in the North Atlantic, kuzira in the North Pacific and australis in the south. A small population in the Arabian Sea does not migrate and has been cut off for about 70,000 years, so it may be a fourth.

Evolution and relatives

A 2018 study of whole genomes placed the split between rorquals and other baleen whales in the late Miocene, 10.5 to 7.5 million years ago. The same study found the humpback and the fin whale to be sister species. A hybrid between a humpback and a blue whale has been reported from the South Pacific. Modern humpback populations arose in the southern hemisphere about 880,000 years ago. They spread into the northern hemisphere between 200,000 and 50,000 years ago.

Like other baleen whales, the humpback descends from toothed ancestors, and its fetus still grows teeth before the baleen forms. The knobs on the head and flippers are unique among large whales and probably evolved as sensors, since they are rich in nerves.

Appearance

Most adults are 14 to 15 metres long, and animals of 16 to 17 m have been recorded. Females run 1 to 1.5 m longer than males, which is rare among mammals. The longest reliable records are 17.4 m for a male and 18.6 m for a female. Body mass reaches 40 tonnes. The body is bulky with a narrow snout, and the flippers are about one third of the body length.

The back is black, and the belly carries patches of black and white that differ from whale to whale. Southern hemisphere whales tend to carry more white. The pattern and scars on the underside of the tail identify each individual, and researchers catalogue them from photographs. One famous all-white animal, Migaloo, is a true albino. The dorsal fin is small and varies from a stub to a curved hook.

Rows of knobs, called tubercles, stud the head and the front edge of the flippers. Each is 5 to 10 centimetres thick at the base and holds at least one stiff hair. The throat carries 14 to 35 grooves that let the mouth swell during a gulp. Between 540 and 800 black baleen plates hang from the upper jaw. A newborn calf is about 4.3 m long and weighs about 680 kilograms.

Habitat and range

Humpbacks occur in all oceans except a few stretches of the equator, the high Arctic and some enclosed seas. The northernmost record is from 81 degrees north near Franz Josef Land. They favour water over the continental shelf and come close to shore on both feeding and breeding grounds. GBIF holds records from 141 countries, a count that reflects how many coastlines the species passes.

Each population feeds in cold water in summer and breeds in warm water in winter. One-way journeys of up to 8,000 kilometres have been tracked. In the North Atlantic, one group winters in the West Indies and feeds off New England, Canada and Greenland. Another winters off Cape Verde and feeds around Iceland and Norway. The North Pacific holds at least four breeding populations, off Mexico, Central America, Hawaii, and Okinawa and the Philippines.

The southern hemisphere is divided into seven breeding stocks that feed around Antarctica. Stock A winters off Brazil, stock D breeds off Western Australia, and the Oceania stocks breed around Tonga, New Caledonia and French Polynesia. The Arabian Sea whales stay in the northern Indian Ocean all year, mainly around Oman.

Diet and feeding

Humpbacks feed from spring to autumn and fast on the breeding grounds. They take krill, copepods and other plankton, and small schooling fish such as herring, capelin, sand lance and mackerel. In the North Atlantic, fish make up about 95% of the diet. Around Antarctica the main food is Antarctic krill. A humpback is a gulp feeder: it takes a mouthful of water and prey, then forces the water out through the baleen.

The best known method is the bubble net. A group swims upward in a shrinking spiral while blowing air, which traps the shoal inside a wall of bubbles. The whales then rise through the centre with open mouths. They may dive to 20 metres to set the net, and lone whales also use it. Some whales add a tail slap on the surface before the final loop, a trick that spread through one population over 27 years. Off Massachusetts, humpbacks brush the seabed with their jaws to flush out sand lance.

In 2009, a dense gathering of feeding humpbacks in Wilhelmina Bay, Antarctica, reached 5.1 whales per square kilometre. Southern whales have been seen feeding in groups of up to 200.

Behaviour and social life

Apart from a mother and her calf, humpback groups last only days or weeks. Larger gatherings form on feeding grounds and where males compete for a female. Humpbacks mix with right whales, fin whales and bottlenose dolphins. They are the most active large whale at the surface. They breach, slap the water with tail and flippers, and throw the rear body sideways in a peduncle throw. These displays may serve as play, as signals, or as a way to shed parasites.

The humpback cruises at 7.9 to 15.1 kilometres per hour, slower than other rorquals, and can reach 27 km/h when alarmed. The long flippers act like wings and let the whale turn sharply and swim in any direction. Dives seldom pass five minutes in summer but last 15 to 20 minutes in winter. Most dives stay above 80 metres, and the deepest recorded reached 616 m. A diving humpback usually lifts its tail clear of the water. It rests at the surface lying flat.

Communication and senses

Male humpbacks sing on the winter breeding grounds. A song runs from 4 to 33 minutes, and a whale off Hawaii once sang for seven hours. It is built from units, phrases and themes in a fixed order, and it carries at least 10 kilometres underwater. All the males in one region sing the same song, and when one changes it, the others copy the change. Songs can spread from one population to the next across several seasons. The purpose is still debated, but singing males gather in groups that females visit, much like birds at a lek.

Other sounds include snorts, grumbles, wops, cries and barks, used between escorts, rivals and mothers with calves. The vocal folds sit almost flat, and a sac in the larynx amplifies the call. Models of the ear suggest hearing from about 15 hertz up to several kilohertz, which matches the range of the calls. The eyes are small and see only outlines at a distance. The smell organs are so reduced that the whale may have no sense of smell at all.

Reproduction and life cycle

Mating happens in winter, when females come into oestrus and male hormone levels peak. Both sexes take several partners. Males trail a female or a mother and calf, and the nearest one, the principal escort, fights off challengers. The fights involve tail slashes, ramming and head butts.

Gestation lasts about 11.5 months, and a female usually calves every two years. She moves into shallow coastal water before the birth, which keeps escorts away, and helps the newborn to the surface. One birth watched off Madagascar took four minutes. A calf suckles for up to a year but can take adult food from six months. Its dorsal fin is folded at birth and stiffens as it grows.

Humpbacks mature at 5 to 15 years, depending on the population, and reach full size at 8 to 12 years. Many live past 50 years, and the oldest known animal was 95.

Predators and threats

Orcas are the only regular predator, and tooth scars on the tails of many adults show attacks survived as calves. A 2014 study off Western Australia found that orcas attack and sometimes kill young humpbacks when calves are plentiful. Mothers and other adults escort calves, and humpbacks mob attacking orcas. They even drive orcas off seals and other whales, probably as a side effect of defending their own young. The flippers, crusted with sharp barnacles, are heavy weapons in these fights.

Large sharks take sick or entangled whales. Tiger sharks killed an ailing humpback near Hawaii in 2006, and great white sharks have killed weakened animals off South Africa. Today the main dangers come from people: fishing gear, ship strikes, underwater noise and warming seas. Along the US Atlantic coast, 88 humpbacks stranded between January 2016 and February 2019, twice the earlier rate. Barnacles and whale lice ride on the skin, and tapeworms and roundworms live inside.

Population and conservation

Whalers hunted humpbacks from the late 1500s, often first in any new area because the whales stayed near the coast. More than 200,000 were killed in the southern hemisphere in the twentieth century and about 28,000 in the North Pacific. The North Atlantic fell to about 700 animals. The Soviet Union reported 2,820 kills between 1947 and 1972, but the true number passed 48,000. The International Whaling Commission banned commercial humpback whaling in 1966, when about 5,000 remained.

By 2018 the IUCN counted about 135,000 humpbacks, of which about 84,000 were mature, and moved the species to Least Concern. The North Atlantic holds about 13,000, the North Pacific about 21,000, and the southern hemisphere about 80,000. The Arabian Sea population holds only about 80 animals and is treated as endangered. The United States, Canada and Australia have lowered the threat status as numbers recovered. Hawaii set up a national marine sanctuary for the species in 1992, and Costa Rica created Ballena Marine National Park.

Relationship with humans

For centuries the humpback supplied lamp oil, machine lubricant, margarine fat, meat, animal feed and bone meal. A few are still taken each year off Bequia in Saint Vincent and the Grenadines, and Greenland received a small quota in 2010. Japan planned to kill 50 in the 2007 season but dropped the plan after protests.

The humpback built the whale-watching industry. Tours began in New England and Hawaii in 1975, and the trade brings Hawaii about 20 million dollars a year. Boats can stress whales and disturb feeding and nursing, so most countries now limit how close a vessel may come. Off eastern Canada, humpbacks feeding near shore damage cod and herring traps. Near the Strait of Magellan they are the whale most often hit by ships, and speed limits have been proposed.

In culture and myth

In Hawaiian tradition the whale is a body form of Kanaloa, the god of the ocean. Polynesian traditions treat whales as sacred travellers that carry messages from the gods, and the song is said to hold ancestral voices. The Maori story of Paikea, who reached New Zealand on the back of a whale, inspired the film Whale Rider. Japanese coastal communities saw whales as guardians of sailors and messengers of sea gods. Bronze Age rock carvings at Bangudae in Korea show whales, and some of them appear to be humpbacks.

The 1970 record Songs of the Humpback Whale, made by Roger Payne, carried the song into homes around the world. It helped turn public opinion against whaling and probably did more for the species than any law. A humpback song travels on the Voyager Golden Record launched in 1977. Modern symbolism writers link the humpback with music, intuition and emotional depth, which seems to come straight from the song.