Animal Info - Humpback Whale

(Other Names: Baleine à Bosse, Baleine à Taquet, Ballena Jorobada, Bunch, Gubarte, Hump Whale, Hunchbacked Whale, Jorobada, Jubarte, Mégaptère, Rorcual Jorobado, Rorqual à Bosse, Rorqual du Cap)

Megaptera novaeangliae

Status: Vulnerable

Contents

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Oceans and Seas Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Size and Weight, Habitat, Age and Size at Maturity, Gestation Period, Birth Season, Birth Rate, Early Development, Maximum Age, Diet, Behavior, Social Organization, Age and Gender Distribution, Mortality and Survival)
5. References

Profile

Pictures: Humpback Whale #1 (38 Kb JPEG) and Humpback Whale #2 (18 Kb JPEG), (Univ. of Mich. 1995-2000)

The humpback whale is a stout, thick-bodied whale weighing an average of 30,000 kg (66,000 lb) (up to 48,000 kg (106,000 lb)). It is approximately 14 m (46') long (up to 18 m (59')). The top of its body is dark blue-black. The color of its bottom surface varies widely, from all black to all white through various degrees of marbling. Its dorsal fin is variable in shape, from almost flat to tall and triangular. The flippers are the longest of any animal, approximately 1/3 of the body length. Humpback whales are commonly found in coastal or shelf waters in high-latitude areas in summer, feeding in the cold, productive waters. In winter, they migrate to mating and calving grounds in tropical or subtropical waters. 

The diet of the Northern Hemisphere humpback whales consists of planktonic crustaceans and small schooling fish. Humpback whales in the Southern Ocean feed mainly on the Antarctic krill. The humpback whale feeds in colder waters during spring, summer and autumn, then migrates to winter ranges in tropical seas, where it calves and breeds. Migrations of the humpback whale are among the longest of any mammal, and are known to reach almost 8000 km (5000 mi). The humpback whale emits a variety of sounds, which can be combined into an elaborate song. There apparently are dialects, in that the song of the whales in one area differs to some extent from that heard in other areas. The social organization of the humpback whale is extremely fluid at both ends of the migratory cycle. With the exception of mother/calf pairs, groups are typically small and unstable, and individuals frequently change companions.

The humpback whale occurs in all oceans and adjoining seas of the world, ranging from the tropics almost to the edges of the pack ice in the polar regions. There appear to be three geographically isolated populations, one each in the North Atlantic, North Pacific and the Southern Ocean. Although commercial whaling seriously depleted all humpback stocks, and these whales are vulnerable to ship collisions, entanglement in fishing gear, and disturbance (even serious injury) from industrial noise, humpback whales have demonstrated remarkable resilience and many of the stocks are recovering.

Tidbits

*** It is not certain how the humpback whales produce their songs. Whales do not have vocal cords and, because they sing while submerged, they cannot afford to release large amounts of air to the exterior (Bonner 1989).

*** Nothing is known for certain about sleep in  baleen whales such as the humpback whale, although it is often assumed that, like some dolphins, they rest one half of the brain at a time (presumably essential to a voluntary breather) (Clapham & Mead 1999).

*** Although humpback whales have a variety of individually unique markings and coloration patterns, the underneath surface of the flukes provides the best opportunity for identifying individuals. When a humpback dives deeply, it will frequently lift the flukes straight out of the water in a fluke-up dive, revealing the coloration and marking/scar pattern on the ventral surface. (Pacific Whale Found.) Approximately 10,000 humpback whales have been identified using photographs of these features (Kemf & Phillips 1994). 

*** The front edges of the humpback whale's flippers have a number of large protuberances, called "tubercles". The length of the flippers and the tubercles on their front edges distinguish the humpback from other whales. Rounded tubercles are also present on the upper and lower jaws. 

*** Etymology of the scientific name of the humpback whale: the genus name ("Megaptera") derives from the Greek "mega" for "large" and "pteron" for "wing", and refers to the humpback whale's huge flippers; the species name ("novaeangliae") refers to New England, where the humpback whale was first described scientifically.

Status and Trends

IUCN Status:

  • 1960's: Vulnerable
  • 1970's - 1980's: Endangered
  • 1994: Vulnerable
  • 1996 - 2004: Vulnerable (Criteria: A1ad) (Population Trend: Increasing) (IUCN 2004)

Oceans and Seas Where the Humpback Whale Is Currently Found:

2004: Occurs in the Antarctic, eastern central, northeast, northwest, southeast, southwest and western central Atlantic Ocean; the Antarctic, eastern and western Indian Ocean; the Antarctic, eastern central, northeast, northwest, southeast, southwest, and western central Pacific Ocean; and the Arctic, Mediterranean and Black Seas. (IUCN 2004)

Countries Where the Humpback Whale Is Currently Found:

2004: Occurs in Angola, Argentina, Australia, Bangladesh, Brazil, Canada, Cape Verde, Chile, Congo, The Democratic Republic of the Congo, Dominican Republic, Ecuador, Fiji, France, Iceland, India, Indonesia, Iraq, Japan, Kenya, Democratic People's Republic of Korea, Republic of Korea, Madagascar, Malaysia, Mexico, Mozambique, New Zealand, Norway, Pakistan, Panama, Peru, Poland, Russia, Solomon Islands, South Africa, Sri Lanka, St. Vincent & the Grenadines, Tanzania, United Kingdom, United States, Vanuatu, and Venezuela (IUCN 2004).

Population Estimates:

WORLD

By Major Ocean

By Region

History of Distribution:

General:

The humpback whale occurs in all oceans and adjoining seas of the world, ranging from the tropics almost to the edges of the pack ice in the polar regions. It feeds in higher-latitude colder waters during spring, summer and autumn, then migrates to winter ranges in tropical seas, where it calves and breeds. 

Because of the reversal of seasons, the populations of the Northern Hemisphere are not in equatorial waters at the same time as those of the Southern Hemisphere. The Northern and Southern Hemisphere populations are regarded as separate, but they are not usually considered to be separate species or subspecies. There appear to be three geographically isolated populations, one each in the North Atlantic, North Pacific and the Southern Ocean.

North Atlantic:

In the North Atlantic, humpback whales feed off the Northeastern USA (from the Gulf of Maine to the mid-Atlantic States), Newfoundland and Labrador, Greenland, Iceland, and Norway. Each of these subpopulations is relatively discrete, with regional fidelity determined matrilineally. However, in the winter, whales from all North Atlantic feeding grounds migrate to common breeding areas in the West Indies, where they mix both spatially and genetically. The principal winter breeding  range is around the Greater and Lesser Antilles. Primary areas are at Silver and Navidad Banks, and along the coast of the Dominican Republic. Other concentrations include the western edge of Puerto Rico and the area from the Lesser Antilles south to Venezuela. The area of the West Indies that includes Silver Bank, Navidad Bank and Samana Bay represents the largest known breeding ground in the world for this species. (Clapham & Mead 1999, Wilson & Ruff 1999)

North Pacific:

During the summer, humpback whales in the North Pacific migrate and feed over the continental shelf and along the coasts of the Pacific Rim, from Point Conception, California north to the Gulf of Alaska, Prince William Sound and along the Aleutian chain into the Western North Pacific. They spend the winter in three separate wintering grounds: 1) The West coast of Baja California, Gulf of California, mainland Mexican coast from southern Sonora to Jalisco, and around Islas Revillagigedo; 2) The Hawaiian Islands from Kauai to Hawaii; and 3) Around islands south of Japan such as Mariana, Bonin and Ryukyu Islands and Taiwan.

Although it is generally thought that there is little mixing of humpback whales between the eastern and western North Pacific, some exchange between these regions clearly occurs, as documented by sightings of the same identifiable individuals in both regions (Wilson & Ruff 1999).

Southern Ocean:

In the Southern Hemisphere there are summer concentrations off the southern ends of continents and around such subantarctic islands as South Georgia. In the autumn the Southern Ocean population migrates north to the coasts of South America, South Africa, Australasia and various South Pacific islands. In tropical areas of the Southern Hemisphere, humpbacks generally are found in their wintering areas - coastal or sheltered waters in the tropics where they breed and give birth - from June to December, but this varies among individuals and across populations (Rosenbaum 2003).

Specific Areas:

Arabian Sea: The sole known exception to the typical seasonal migratory pattern is a population in the Arabian Sea, which is unique in that it appears to both feed and breed in tropical waters (Clapham & Mead 1999).

Coast of Western Africa: In 1998, groups of whales were first observed off of the coast of Gabon, including groups involved in behavior only seen in mating areas. (Walsh 1999)

Madagascar: A new wintering ground for humpback whales was identified in Baie d’Antongil, Madagascar in 1996. Mothers were observed with newborn calves, suggesting that it is a calving and nursing area. (Rosenbaum et al. 1997)

Hawaii: Detailed observations of individuals indicate that at least a percentage of the population returns to Hawaii each year. It is thought that they have used Hawaiian waters only during the last 200 years.

Northern Indian Ocean: It appears that there may be a small, possibly resident, population in the Northern Indian Ocean, although this could be a wintering area for a component of the population summering in the Antarctic (Klinowska 1991).

Threats and Reasons for Decline:

Humpback whale populations were considerably reduced by whaling.  By the 1960's it was generally realized that they were nearing extinction. Commercial harvesting of humpback whales was banned in the North Atlantic in 1956, in the Southern Ocean in 1963, and in the North Pacific in 1966. (Klinowska 1991) Currently, whaling on this species is minimal (Clapham & Mead 1999).

Known threats to humpback whales include entanglement in fishing gear and ship strikes, although it is questionable whether the mortality involved in either is significant at the population level. In addition, existing data suggest that baleen whales, including humpbacks, do not carry high contaminant burdens. (Clapham & Mead 1999).

Although commercial whaling seriously depleted all humpback stocks, and these whales are vulnerable to ship collisions, entanglement in fishing gear, and disturbance from industrial noise, humpback whales have demonstrated remarkable resilience and many of the stocks are recovering (Reeves et al. 2003).

Data on Biology and Ecology

Size and Weight:

Maximum recorded size is 18 m (59'), with an average length of 14.5 m (47.6') for females and 13.5 m (44.3') for males.

Average weight: 30,000 kg (66,000 lb); up to 48,000 kg (106,000 lb).

Habitat:

Humpback whales are commonly found in coastal or shelf waters in high-latitude areas in summer, feeding in the cold, productive waters. In winter, they migrate to mating and calving grounds in tropical or subtropical waters, where they are generally found associated with islands or offshore reef systems. These whales frequently travel across deep water during migration. (Clapham & Mead 1999, Wilson & Ruff 1999)

The humpback whale is a relatively eurythermic animal, occupying cold-temperate to tropical waters. 

The humpback whale occurs in the Antarctic Peninsula & Weddell Sea, Eastern Polynesian Islands Marine Ecosystems, Galapagos Islands Marine Ecosystems, Grand Banks, Great Barrier Reef, Panama Bight Marine Ecosystems, and Southern Caribbean Sea Global 200 Ecoregions. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)

Age and Size at Maturity:

Both males and females mature sexually at around 4 - 6 years (average - 5 years). The average length at the average age at attainment of sexual maturity (5 years) is 12 m (39') for both males and females. Physical maturity is not reached until 8 - 12 years after sexual maturity (Clapham & Mead 1999). 

Gestation Period:

Approximately 11 - 12 months (Clapham & Mead 1999).

Birth Season:

Calving occurs primarily in the winter (October - March in the Northern Hemisphere and April - September in the Southern Hemisphere). The peak birth months in the northern and southern hemisphere populations are early February and early August, respectively (Clapham & Mead 1999).

Breeding is strongly seasonal. Most courtship and mating behavior occurs in winter. Females come into estrus in mid-winter, and testosterone production and spermatogenesis peak at that time in males. (Wilson & Ruff 1999)  

Birth Rate:

A single young is born. The average interbirth interval is approximately 2.4 years (Clapham & Mead 1999). Most female humpback whales give birth every 2 - 3 years.  Annual and multi-year (up to 5 years) intervals between calving have also been observed.

North Pacific: Gerber & DeMaster cited observations of birth intervals that yielded estimates of annual reproductive rates on breeding grounds of 0.58 calves/female/year and on feeding grounds of 0.38 calves/female/year.  Another estimate of average birth interval of 2.31 (standard error = 0.26) yielded a corresponding annual birth rate of 0.43 (standard error = 0.075) calves/female/year. (Gerber & DeMaster 1999)

Early Development:

Calves nurse for up to a year, although they may begin to feed independently at approximately 6 months. The great majority of calves leave their mothers during, or shortly before, their second winter. Average lengths at independence (one year of age) were approximately 9.8 m (32') for both females and males.  (Clapham & Mead 1999)

Maximum Age:

Some individuals are estimated to have lived as long as 77 years (Nowak 1999).

Diet:

The diet of the Northern Hemisphere humpback whales consists of planktonic crustaceans and small schooling fish such as herring, capelin, pink salmon, Arctic cod, walleye pollack, sardine, mackerel, anchovy and haddock. Humpback whales in the Southern Ocean feed mainly on the Antarctic krill, Euphausia superba.

Like other rorquals, humpbacks fast during migration. Most feeding occurs during the summer, in high latitudes.

Humpback whales are termed "gulp-feeders." They feed in discrete events, rather than continuously filtering their prey as do some other whales (called "skim-feeders"), such as the North Atlantic right whale. Typically, the humpback whale lunges into a prey school and engulfs a huge volume of water and food. This process is aided by the whale's long, flexible throat grooves, which expand during a feeding lunge and thus greatly increase the capacity of the whale’s mouth. The water is forced out through the whale's baleen plates. The prey are trapped in the whale's mouth, by the fringe of hair that lines the inner surface of the baleen plates, and then swallowed. (Wilson & Ruff 1999)

Bubble-netting: Humpback whales are unique in that they engage in a feeding technique called "bubble-netting".   This involves one or more whales diving beneath a school of fish and then swimming upward in a spiral, while releasing streams of air from their blowholes and creating bubbles.  The bubbles rise in a cylindrical curtain around the fish and seem to form a barrier through which the fish will not pass.  The whales then swim up through the school of fish, feeding as they go.

Bubble structures in the form of nets, clouds or curtains are commonly observed in all studied populations, notably when whales are feeding on schooling fish. Bubble feeding is practiced by lone whales and also cooperatively by animals in groups of different sizes. In the latter, acoustic coordination of behavior by a lead whale has been suggested but not conclusively demonstrated (Clapham & Mead 1999). A bubble cloud - which seems to be unique to the North Atlantic population - is a single burst of bubbles up to 20 m (66') across which presumably functions to trap prey between the rising cloud and the surface (Wilson & Ruff 1999).

Behavior:

Migration: The humpback whale feeds in colder waters during spring, summer and autumn, then migrates to winter ranges in tropical seas, where it calves and presumably breeds. Migrations of the humpback whale are among the longest of any mammal, and are known to reach almost 8000 km (5000 mi). Migrations to and from the tropics are loosely staggered by sex and state of maturation. Lactating females are among the first to leave the feeding grounds in late autumn, followed by immature animals, mature males, "resting" females, and lastly pregnant females. In late winter, this order is broadly reversed during the migration back to high latitudes. (Clapham & Mead 1999)

Recent studies have challenged the widespread belief that all humpback whales migrate every year, and a population in the Arabian Sea appears to be unique in that it remains in tropical waters year-round. (Wilson & Ruff 1999)

Swimming: Relative to other whales in its family, humpbacks are not fast swimmers. Swimming speeds of animals traveling or migrating range from 8 - 15 km/h (5 - 9 mi/h). The maximum reported was a burst of speed of 27 km/h (17 mi/h) by a wounded whale being chased by a whaling boat. (Clapham & Mead 1999)

Diving: Diving behavior varies by time of year. In summer, most dives last less than 5 minutes, and dives exceeding 10 minutes are unusual. In winter, dives average 10 - 15 minutes, and dives of more than 30 minutes have been recorded. In this season, many long-diving whales appear to be submerging to rest, an activity which commonly takes place at the surface on the summer feeding grounds. (Clapham & Mead 1999)

Singing: The humpback whale emits a variety of sounds, certain of which can be combined into an elaborate song. Singing is virtually ubiquitous in the species’ breeding range in winter, and it has occasionally been recorded on the feeding grounds in summer and fall, as well as on migration. A song is produced only by single individuals, which are thought to be young but sexually mature males. Singers will sometimes sing continuously for hours or even days. There apparently are dialects, in that the song of the whales in one area differs to some extent from that heard in other areas. The songs vary from year to year, but, within each ocean, in each year the same new version of the song spreads throughout the different breeding groups.

The sounds are mostly in the frequency range 40 - 5000 Hz. There are six basic types of song, each of which can be sung in one of several variations. In the terminology of bird songs, the humpback sings a true song, consisting of an ordered sequence of themes comprising motifs and phrases made up of syllables. The syllables are the simplest part of the song and they have been given more or less descriptive names: moans, cries, chirps, yups, ooos, surface rachets and snores. The duration of the song is generally between 6 and 35 minutes.   (Bonner 1989) 

Acrobatics: More than any other whale, the humpback engages in often spectacular aerial behaviors. These include breaching (the whale jumps headfirst out of the water, twists in the air, and falls on its back with a tremendous splash), lobtailing (the tail is repeatedly slammed down), and flippering (one flipper slaps the surface). These displays are seen at all times of year and among all age classes. Their purpose is unknown.

Social Organization:

The social organization is extremely fluid at both ends of the migratory cycle. With the exception of mother/calf pairs, groups are typically small and unstable, and individuals frequently change companions. In the summer feeding season, individuals may feed alone or together. Stable groups which remain together over weeks or even for several feeding seasons have been recorded in the Gulf of Maine and Alaska, but these represent a clear exception to the general pattern of social behavior during summer. Such groups do not appear to consist of related animals, and indeed kinship seems to be of little importance among humpback whale associations. (Clapham & Mead 1999)

In the winter breeding season, animals are usually found alone or in groups of 2 - 15 (most frequently 3 - 5). A female and young calf commonly are accompanied by another adult, evidently a male. However, the pair bond is not stable. This escort male is aggressive toward other males that approach.  Other males may join the group, and jostling for position near the female takes place. One of the newcomers may displace the original escort. No stable groups have been documented on the breeding grounds. 

Age and Gender Distribution:

The current male:female ratio in several studied populations is thought to be close to 1:1 (Clapham & Mead 1999).

Mortality and Survival:

Calf and non-calf survival rates have been estimated at 0.875 (standard error = 0.047) and 0.96 (standard error = 0.008) respectively for the summer feeding population in the Gulf of Maine (Clapham & Mead 1999).

References

Allen 1942, Bonner 1989, Chivers 1999, Clapham & Mead 1999, Curry-Lindahl 1972, Gerber & DeMaster 1999, Hooker et al. 1999, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, Kemf & Phillips 1994, Klinowska 1991, NMFS 1994, NMFS 1999, Nowak 1999, Nowak & Paradiso 1983, Pacific Whale Found., Primack 1993, Reeves et al. 2003, Rosenbaum et al. 1997, Rosenbaum 2003, Straley 1994, Univ. of Mich. 1995-2000, Walsh 1999, Wilson & Ruff 1999

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