The humpback whale is a baleen whale of medium size, measuring 11-17 m as adults and attaining a weight of at least 35 tons. Newborns are about 4.3 m in length. The humpback is distinguished by its long flippers, one-fourth to one-third the length of its body, which have a series of bumps, two of which are found in consistent positions on the leading edge. Their heads are covered in large bumps, called "stove bolts," each containing a single sensory hair. Their large flukes are concave with a serrated trailing edge and individually vary in the pigmentation pattern found on the dorsal surface of their fluke. The black and white pigmentation pattern allows for researchers to individually identify members of the population.
Can be Confused With
At close range, the humpback is one of the easiest whales to identify. At a distance, however, there can be some confusion with other large whales, especially right, gray, and sperm whales. This is largely due to the similarity in their bushy blows. When a closer look is obtained, humpbacks are generally unmistakable, distinguished by their massive flippers and robust body plan.
Humpback whales are cosmopolitan in that they are found in all the major ocean basins, and like other baleen whales, they migrate long distances. In the summer, humpbacks migrate poleward to exploit the high productivity of the cold waters. In winter humpbacks travel to warm tropical waters, where they concentrate on mating and calving. The humpback whale is better studied than other balaenopterid species, and migratory patterns are known for some stocks.
In the North Pacific, four stocks are believed to exist:
Stock 1. Winters off the coast of Mexico (Baja California, Gulf of California, mainland) and summers off the coasts of California, Oregon, and Washington.
Stock 2. Winters in offshore Mexican waters, near the Revillagigedo Islands; summer grounds unknown.
Stock 3. Winters in the central North Pacific and Hawaiian Islands; summers in Alaska (Prince William Sound) and British Columbia, and
Stock 4. Winters in the western North Pacific, near Japan and Taiwan; summers in the Bering Sea and the coast of the Aleutian Islands, west of the Kodiak Archipelago.
In the eastern North Atlantic, humpback whales summer off Iceland, Scotland, Norway, and Novaya Zemlya in the Barents Sea. The only known wintering ground in the eastern North Atlantic is near the Cape Verde Islands. In the western North Atlantic, five separate feeding aggregations are found:
1. Iceland-Denmark Strait,
2. Southwest Greenland,
3. Southern Labrador and east of Newfoundland,
4. Gulf of St. Lawrence, and
5. Gulf of Maine/Nova Scotia.
Photo-identification indicates that whales from all five of these groups migrate to the Caribbean for the winter, concentrating on Silver Bank and Navidad Bank near the Dominican Republic. Other known wintering grounds are Samana Bay (Dominican Republic), the northwest coast of Puerto Rico, the Virgin Islands, and the eastern Antilles all the way to Venezuela. Some whales have also been sighted in northern waters during the winter, indicating that not all humpback whales migrate to wintering grounds every year.
In the Northern Indian Ocean, a poorly studied resident stock, which does not migrate, is found in the Arabian Sea.
In the Southern Hemisphere, wintering grounds include Abrolhos Bank, Brazil, the coasts of Gabon, Angola, Congo, Mozambique (Sofala Bank), Madagascar, and near Cape Leveque in western Australia. In summer, whales are found in well-defined feeding areas in Antarctic waters, in waters near South Shetland and South Georgia, and along the west and east coasts of Africa, Australia, and South America.
Ecology and Behavior
Humpback whales inhabitat coastal waters. Although they generally occur singly or in small groups, larger aggregations develop in feeding and breeding areas. The humpback whale is estimated to reach sexual maturity between the ages of four and nine. Females calve every two or three years on average, but annual calving is believed to occur (though infrequently) and longer spans between calving have also been documented. Gestation lasts twelve months and calves are believed to nurse for a year. On the breeding grounds, males compete for access to estrous females, apparently using complex "songs" as part of their breeding display. Calves are born on wintering grounds in tropical and subtropical regions.
Feeding and Prey
Humpback whales possess 14-35 ventral grooves and 270-400 baleen plates on each side of the mouth. The ventral grooves expand outward when humpback whales are feeding, to enlarge the size of their mouth, allowing them to take in more food and sea water in each gulp. The baleen plates act as strainers, then, once the whale has taken in food and sea water. The baleen plate will trap prey items in their mouth as the sea water is pushed out in between the baleen plates. Humpback whales, as is the case with all marine mammals, cannot consume a lot of sea water as it would dehydrate them.
Humpback whales exhibit a wide range of feeding habits intended to concentrate prey, which may be employed individually or in groups. "Bubble-netting" and "lob-tail feeding" are well documented strategies. Bottom feeding has also been documented.
Humpback whales have a broad diet that is focused on crustaceans > fish > other invertebrates
Humpback whales are generalists, lunging for krill, copepods, fish, and cephalopods. Humpbacks rarely feed in winter, foraging during summer in areas of prey concentration such as upwelling regions.
Humpback whales have been hunted by commercial whalers in all major oceans, and many stocks have been seriously depleted. They were taken both by coastal and oceanic whaling operations, and some have continued to be taken by artisanal whalers in the Caribbean and the South Pacific in the past few decades. The species has been fully protected by the International Whaling Commission since 1965, but the Russians took tens of thousands of them illegally until 1973. The North Pacific population was estimated to have been reduced to around 1,000 animals by decades of commercial whaling. Some aboriginal subsistence hunting continues.
Additional threats include entanglements in fishing gear, vessel collisions, disturbance by human-caused noise and traffic, and coastal habitat destruction. Globally, there may be about 30,000-40,000 humpback whales. Many stocks are still depleted, while others are showing evidence of strong recovery.
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Leatherwood, S. and R.R. Reeves. 1983. The Sierra Club handbook of whales and dolphins. Sierra Club Books, San Francisco, California.
National Marine Fisheries Service. 1991. Recovery plan for the humpback whale (Megaptera novaeangliae). Prepared by the Humpback Whale Recovery Team for the National Marine Fisheries Service, Silver Spring, Maryland. 105 pp.
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Status - ESA, U.S. FWS
E (Central America) E (Cape Verde Island/Northwest Af...) E (Arabian Sea) E (Western North Pacific) T (Mexico)