Humpback Whale

Megaptera novaeangliae

Description

The humpback whale, Megaptera novaeangliae, is a robust whale, thickened about the middle, then tapering quickly after the dorsal hump and fin. Adults range from 39-50 ft (12-15 m) in length and weigh from 25-45 tons (23-41 metric tons). The head is distinctly flattened and crowned with numerous knobs of varying size. The scalloped flippers are long and wing-like, extending up to a third of the total body length, with fleshy knobs along the front margins. Throat furrows, numbering 14-20, extend to the navel. Coloration is a black or charcoal gray above, white beneath. Flukes (the tail displayed when diving) are marked with a distinctive black and white pattern that can be used to identify individual whales.

In addition to the humpback whale, seven other whale species are federally listed as Endangered: the right (Balaena glacialis ), bowhead (Balaena mysticetus ), sei (Balaenoptera borealis ), blue (Balaenoptera musculus ), finback (Balaenoptera physalus ), gray (Eschrichtius robustus ), and sperm (Physeter catadon ). Within two suborders of toothed and baleen whales, there are a total of 11 families, 38 genera, and 92 species.

Behavior

The humpback whale is a comparatively slow swimmer, making a top speed of about 11 mph as it follows schools of fish. It feeds on herring, sand lance, capelin, mackerel, cod, salmon, plankton, and crustaceans, which it strains from the water with its baleen.

Strongly migratory, humpbacks congregate in groups as large as 200 at feeding grounds in polar waters and disperse to breeding grounds in more shallow, tropical waters. Whales winter at the breeding grounds in a small group consisting of a cow, a calf, and a single male, termed an "escort." Escorts are thought to be waiting for the cow to come into estrus. Sometimes another male joins the group, and competition between males ensues, resulting in a vigorous contest of bubble-blowing and tail-lashing. The victorious male takes over the role of escort.

Mating humpbacks lie stomach to stomach and rise out of the water at right angles to the surface. Copulation lasts only a few seconds. After a gestation period of 11 or 12 months, the cow typically bears a single calf in November just before arriving at the breeding grounds. Twins are born one in every 100 births, the same rate as for humans. Calves nurse underwater and are weaned at between five months and a year of age. Most cows bear young at intervals of two or three years.

This species is usually recognized by its pear-shaped blow, however it is clearly distinguished by its breaches, displaying its unique body contours. The whale may leap completely out of the water and spin partially as it falls with a resounding smack. Sometimes it rolls on the surface, slapping the water with its flukes or flippers. Occasionally, humpback whales will hold one flipper in the air while lying on one side or both. The humpback whale is noted for its singing, which is considered the most complex vocalization in the animal kingdom. Songs are built from a repertoire of moans, groans, snores, grunts, chirps, and squeals, and arranged into a fixed order of repeated phrases and syllables. Individual songs are recognizable and can be attributed to specific whales.

Habitat

Humpback whales migrate in the open ocean to cool polar waters in summer and to warmer tropical waters in winter. They are often observed within the Continental Shelf or near island archipelagos and will occasionally enter broad river estuaries. Many summer feeding areas are used year after year by the same whales.

Distribution

Humpback whales are found worldwide and appear to be divided into at least ten geographically defined sub-populations with concentrations in the North Atlantic and near the Hawaiian Islands. Before whaling peaked after the turn of this century, it was estimated that more than 15,000 humpbacks lived in the Pacific Ocean alone and 22,000 in the Antarctic region. The Atlantic population was probably larger than either of these.

The humpback whale still occurs throughout its range in greatly reduced numbers. While no estimates have been made for the Eastern North Atlantic, the Western North Pacific, or the Northern Indian Ocean populations, in the early 1990s estimates were made of 5,505 in the Western North Atlantic, greater than 1,407 in the Eastern North Pacific, and greater than 3,000 in the Southern Oceans. These numbers represent a decline from pre-hunting estimates of 15-18%.

Threats

The greatest threat to all whales, the humpback included, has been whaling. Before the development of the petroleum industry, whales were an important source of lamp oil and were used in the manufacture of glue, gelatin, and margarine. Whale bones were used as stays for corsets.

Conservation and Recovery

Serious measures to protect whales were first taken in 1946 with the establishment of the International Whaling Commission (IWC), which regulated whaling and placed inspectors aboard every whaling ship. Since 1966, the humpback whale has been protected from hunting altogether, although a small number are taken each year by native whalers off the coast of Greenland and off Bequia in the Caribbean. In spite of this ban, the humpback whale has recovered very slowly.

In 1988, the National Marine Fisheries Service (NMFS) initiated recovery efforts for the humpback and right whales. Under the Endangered Species Act, the NMFS, a part of the Commerce Department, is responsible for developing and implementing recovery plans for federally listed marine species. Recovery teams have been appointed, and plans will soon be available for public review.

One of the whale's most critical habit areas, the waters of Hawaii, hosts about two-thirds of the migrating North Pacific humpback whale population (approximately 2000-3000 whales), who go to America's tropical state to engage in breeding, calving and nursing activities. The continued protection of humpback whales and their habitats is crucial to the long-term recovery of this endangered species. And so, the U.S. Congress, in consultation with the State of Hawaii, recognized the importance of Hawaii's nearshore waters to humpbacks by designating the Hawaiian Islands Humpback Whale National Marine Sanctuary on November 4, 1992.

The Hawaiian Islands National Marine Sanctuary Act, which established the 1,300 sq mi (3,400 sq km) sanctuary, identified the following purposes for the Sanctuary: 1) to protect humpback whales and their habitat within the Sanctuary; 2) to educate and interpret for the public the relationship of humpback whales and the Hawaiian Islands marine environment; 3) to manage human uses of the Sanctuary consistent with the Hawaiian Islands National Marine Sanctuary Act and the National Marine Sanctuary Act; and 4) to provide for the identification of marine resources and ecosystems of national significance for possible inclusion in the Sanctuary.

The Sanctuary's designated boundary includes the area from the high water mark to the 100-fathom (600 ft) isobath around the islands of Maui, Molokai, Lanai; and including Penguin Bank; the Pailolo Channel; and a small portion off Kilauea Point, Kauai.

In addition, in June 1993, Still Wagon Bay off the Coast of New England was designated as a protected marine sanctuary to protect resident populations of humpback, as well as finback, sei, meinke, and E. glacialis.

To ensure future healthy populations of all whales, extensive biological studies need to be undertaken to determine breeding habits and seasons, reproductive rates, and population trends. Systematic research is currently underway for the Hawaiian humpback population. An IWC-sponsored survey, released in June 1989, counted over 4,000 humpback whales in Antarctic waters. Contrary to findings for other whale species, which suggested a serious decline across the board, numbers for the humpback were at least 1,000 more than anticipated in these waters.

According to the National Marine Fisheries Service 1991 Recovery Plan for the Humpback Whale, the overall recovery goal for this species is to increase its population numbers to at least 60% of the pre-hunting total. This accomplished, the species will be considered biologically successful so that populations will be buffered against normal environmental fluctuations or artificial catastrophes caused by humanity.

Specific objectives to reach this goal include maintaining and enhancing habitats used by the species currently or historically; identifying essential habitat; examining potential for reintroduction to historically used sites; identifying and minimizing potential adverse impacts; developing federal-state-local-international agreements to protect the species; identifying and reducing direct human-related injury and mortality; measuring and monitoring key population parameters; estimating historic population sizes; improving current population estimates; conducting research on population dynamics; and improving administration and coordination of recovery programs.

Contacts

Office of Protected Resources
National Fisheries Service
1315 East-West Highway
Silver Spring, Maryland 20910

U.S. Fish and Wildlife Services
Division of Endangered Species
Mail Stop 420ARLSQ
1849 C St., NW, Washington, D.C. 20240

References

Baker, C. S., and L. M. Herman. 1984. "Aggressive Behavior Between Humpback Whales on the Hawaiian Wintering Grounds." Canadian Journal of Zoology 62:1922-1937.

Baker, M. L. 1987. Whales, Dolphins, and Porpoises of the World. Doubleday, Garden City.

Hoyt, E. 1984. The Whale Watcher's Handbook. Doubleday, Garden City.

Norris, K. S., ed. 1966. Whales, Dolphins, and Porpoises. University of California Press, Berkeley.

Payne, R. 1970. "Songs of the Humpback Whale." Capitol Records SW-620.

Payne, R., ed. 1983. Communication and Behavior of Whales. AAAS Series No.76, Westview Press, Boulder.

humpback whale (Megaptera novaengliae) See BALAENOPTERIDAE.

Megaptera novaeangliae (humpback whale) See BALAENOPTERIDAE.