HUMPBACK WHALES

Pacific Whale Foundation's Facts

The humpback whale is the fifth largest of the world's great whales. Distinct populations of humpback whales are found in each of the world's oceans. Newborn calves, weighing an average of 1.5 tons, range from 10 to 16 feet in length. Males may reach 43 feet in length, while females are slightly larger, averaging 45 feet. A mature humpback weighs up to one ton per foot, or about 85,000 - 90,000 pounds.

Researchers believe humpbacks live approximately 40 - 60 years, grayish-black in color, humpback whales have white markings that are distinct to each individual. A whale swims by moving its tail or fins up and down (fish move their tails from side to side).

The flippers or pectoral fins, located on each side of the whale, are used to turn and steer. These fins are actually modified forelimbs, with a bone structure similar to that of the human hand and arm. Humpback whales breathe through a double blowhole located on top of their head.

A Humpback's head has tubercles (fleshy knobs) along the upper and lower jaws. Each turbercle has a single hair and is believed to enhance sensory ability. Expandable ventral throat pleats increase the capacity of the mouth during feeding.

The humpback's scientific name, Megaptera novaeangliae ("Great Wings of New England") refers to its huge fifteen-foot pectoral fins. The name "hump-back" coined by whalers, probably resulted from the appearance of the arching of the caudal peduncle while diving, coupled with the prominent dorsal fin.

In Hawaii, the word kohola refers to the general category of whale; there is no specific name for humpback.

Migration and Distribution

North Pacific humpbacks spend their summer in temperate waters from the Aleutian Islands of Alaska to the Farallon Islands off the coast of central California. During the colder winter months, November to May, the majority of the North Pacific stock is found in the warm waters of Hawaii where they breed, calve, and nurse their young.

The remaining animals are found off the coast of Baja California, Mexico, and throughout the islands of south Japan. In the South Pacific, humpbacks feed near Antarctica in the austral summer, November to May, and spend the austral winter, June to October, breeding off east Australia and South Pacific Islands. Consequently, researchers believe northern and southern stocks do not intermingle.

Humpbacks are not fast swimmers. While they can attain speeds of 20 mph for brief periods, they average three to six mph during migration. How long it takes to travel the more than 3,500 miles between the feeding and breeding areas is not known. At least one animal traveled the distance in less than 80 days.

Timing of the migratory cycle ensures that pregnant females and mothers with new-born calves spend the majority of their time in relatively warm water. Research indicates that humpbacks may use acoustical cues, currents and temperature changes, and even the earth's magnetic field to "hone in" on their breeding and feeding grounds.

Some movement of individual humpback whales between breeding areas have been documented. Whales photographed in Hawaii in one year have been observed in Mexico and south of Japan in other years.

One whale was observed in both Mexico and Hawaii during the same winter!

Reproduction

Humpback calves are both conceived and born near Hawaii; the gestation period is 10-12 months. Although sightings of calves are common during the winter, no well-documented evidence of an actual birth exists. After a calf is born, it's mother will remain close to shore, resting and nursing her newborn.

Calves survive on their mother's fat-rich milk for six to eight months. They grow at an astounding rate, nearly doubling in length in their first year. Often mothers and calves are accompanied by a third whale called an escort. The escort whale, assumed to be a sexually active male, remains with the mother and calf for less than a day, with most associations lasting a few hours. Males and females do not form long-term pair bonds.

Although it has never been documented, mating may occur in association with large surface-active groups of whales which include a single receptive female who is pursued by a number of males. Competition for the female involves a variety of intensely aggressive behaviors that may occasionally escalate and result in death.

Communication and Song

Humpback whales produce a wide array of sounds, including the highest and lowest frequencies humans can hear. Humpbacks do not have functional vocal cords; evidence suggests that their sounds are produced by valves and muscles in a series of blind sacs which branch off in the respiratory tract.

During the winter breeding season, male humpbacks produce long complex patterns of sound called "songs" which they repeat for extended periods. Discrete notes occur in patterned sequences that make up a phrase.

Usually uniform in duration, phrases may contain repeated sounds. A consecutive group of phrases constitutes a theme. Although a given theme may vary in the number of phrases it contains, its sequence is always the same. Similarly, the sequence in which themes occur is always the same, although some themes may be left out. A predictable series of themes forms a song.

Researchers believe the song may serve to attract females, to scare away other males, or to maintain the distance between singers. A song generally lasts between six and eighteen minutes. A male may repeat his song many times with a minimum of pause.

An analysis of songs collected from Mexico, Hawaii, and Japan within the same season indicates virtually all North Pacific Humpbacks sing nearly the same song. As the season progresses, small changes occur in the song. When the whales return to the breeding grounds the following winter, they sing the version popular at the end of the previous breeding season.

Identification

When a humpback dives, it may lift its tail out of the water, allowing observers to view a unique pigmentation pattern on its underside. Each humpback can be individually identified by a photograph of this "natural tag".

These fluke identification photos can be catalogued with information about the date and time of the sighting, pod composition, travel direction, and presence / absence of a calf. More than two thousand humpback whales have been individually identified in the North Pacific.

As whales are re-identified on subsequent occasions, these re-sights provide important insight into migratory routes, population estimates, social structures, behavior, longevity and reproductive rates. Photo-identification and other benign research techniques (such as acoustic monitoring, genetic analysis, and satellite tracking) remove the need to kill endangered whales in order to understand them.

Behavior Key

The following variety of behaviors, most visible from boats and shoreline lookouts, are high energy activities that may serve a number of social functions. They must be interpreted in the full context of the season and location in which it occurs to understand their significance and purpose.

Blow:
The normal pattern of exhalation and inhalation at the surface. This term refers to both the act of breathing and the cloud of water condensation produced above the animals head during the process of exhalation.

Round Out / Peduncle Arch:
The whale begins a diving descent by arching its body slightly while rolling ahead at the surface (round out). As the caudal peduncle appears, the whale may arch high above the water, perhaps in an attempt to dive more deeply (peduncle arch).

Fluke Up / Fluke Down Dive:
Following a peduncle arch, the humpback will usually bring its flukes above the surface of the water. In a fluke up dive, the flukes will be brought straight up into the air, exposing the entire ventral surface, and displays the unique pattern of markings found on each whale. In a fluke down dive, the flukes are brought clear of the water but remain turned down, so that the ventral surface is not exposed.

Pec Slap:
Humpbacks frequently roll at the surface, slapping their pectoral fins against the water. Humpbacks also lay on their back waving both fins in the air at the same time before slapping them on top of the water.

Head Rise:
The whale rises relatively straight up out of the water rather slowly, maintains its head above the surface to just below the eye, often turns 90-180 degrees on its longitudinal axis, and then slips back below the surface.

Tail Slap:
This forceful slapping of the flukes against the surface of the water can be carried out while the whale is lying either dorsal up or ventral up in the water.

Peduncle Slap:
An aggressive behavior in which the rear portion of the body, including the caudal peduncle and the flukes, is thrown up out of the water and then brought down sideways, either on the surface of the water or on top of another whale.

Head Slap:
Lunging head-first out of the water, the whale pounds its massive, sometimes partially engorged mouth on the water's surface. The head can rise 20 feet above the water at the peak of the display.

Breach:
The whale propels itself out of the water, generally clearing the surface with two-thirds of its body or more. As the whale rises above the water, it throws one pectoral fin out to the side and turns in the air about its longitudinal axis.

Feeding

North Pacific humpback whales feed on small schooling fish (e.g., herring, smelt and sand lance) during the summer months when fish stocks are most productive. South Pacific humpbacks feed primarily on krill near Antarctica.

Humpbacks can consume nearly a ton of food in a day's time. During their summer feeding cycle, they store enough energy to last the rest of the year.

Generally, they do not feed on the winter breeding grounds, although limited evidence suggests they may feed opportunistically en route and near their breeding grounds.

Status

Prior to extensive commercial whaling, the North Pacific humpback whale stock may have numbered 15,000 animals. Commercial whaling reduced the population to fewer than 1,000 by 1966, prompting international protection.

In the early 1970's, humpbacks were afforded additional protection in U.S. waters by the Marine Mammal Protection Act and the Endangered Species Act. By 1993, the North Pacific stock was estimated to number 2,500 to 3,000 whales.

Scientists believe that nearly two-thirds of the stock migrates to Hawaii each winter to engage in reproductive activities. Although the North Pacific humpback population has shown initial signs of recovery since 1966, they remain an endangered species.

Because Extinction is Forever

Pioneers in whale research, the Pacific Whale Foundation has been a leader in the fight to save humpback whales from extinction since 1990. A non-profit, tax exempt 501(c)(3) organization, the Pacific Whale Foundation actively studies whales and dolphins throughout the Pacific to explore the factors than ensure their survival and recovery.

Humpback whales are still threatened by commercial whaling, as well as commercial and acoustic pollution, marine debris, destructive fishing practices and the loss of habitat through human encroachment. Pacific Whale Foundation urges you to become active in the fight to protect humpback whales and their precious ocean home.

For more information on how you can become involved with the Pacific Whale Foundation's research, conservation and education programs go to: http://pacificwhale.org/index.html

Pacific Whale Foundation's Hawaiian Humpback Whale Research Study
Project Title: Recovery of Hawaiian Humpback Whales
Research Site: Maui, Hawaii

Background

The humpback whale (Megaptera novaeangliae) migrates each winter from high latitude feeding grounds to wintering areas closer to the equator. The behavior of the whales while in the wintering areas and status of their reproductive physiology indicate that breeding and calving activities are dominant on the wintering grounds.

The Hawaiian archipelago is thought to comprise the largest population of the three known breeding grounds for the Northern Pacific humpback stock. A second breeding ground is found in Mexican waters around the Baja Peninsula, Gulf of California, and Islas de Revillagigedo. The third is found south of Japan, among the Ogasawara, Ryukyuan and Marianas Islands.

Adult humpbacks vary in length from 40-50 feet, the females being slightly longer than the males, and weigh up to 55 tons. Their coloration is generally black dorsally and white ventrally, with many possible variations. Photographs of the variations in pigmentation pattern of the tail-flukes, differences in lateral body markings, variation in the shapes of the dorsal fins and the disposition of the body scars all provide the opportunity to individually identify unique whales.

Humpback whales feed from June to September on euphausiids (see note below) and schooling fish in Alaska. Estimates of Australian humpback migratory speeds range from 1.7 to 2.0 kilometers per hour (0.1 to 1.1kt). Investigations in Hawaiian waters yielded a 67 day re-sight between Alaska and Hawaii supporting the estimated speed of 1.7 (0.9kt) kilometers per hour.

The animals begin arriving in Hawaii as early as late October. The peak of the annual migration occurs in February and March while some animals delay departure until late May or early June. Animals appear to remain on the wintering grounds for six to eight weeks.

The population of North Pacific humpbacks has recently been estimated to number about 6,000 individuals, with about 4,000 whales using the Hawaiian Islands. Because whales move throughout the islands and between the three different breeding grounds, earlier estimates of the abundance of humpbacks in the North Pacific were much lower.

Humpback whales sing complex songs which are subject to continual and gradual change during the winter breeding months. Humpbacks sing distinct songs in different geographical areas, e.g., songs from the Northern Atlantic and the Eastern Pacific differ greatly, as do songs from the North Pacific and South Pacific. Within a region, song changes during the course of a winter season, but at any given time, singers within the region engage in the same or similar rendition.

The exact function of the song remains speculative: we do know that only males have been identified as singers, and we know that singing peaks during the winter months, although portions of song have been heard on the summer feeding grounds and along the migratory pathways. There is a general agreement that, because of the correlation between song production and gonadal activity, the song is associated with mating displays.

Responses of whales to approaches by boats

A collaborative study between PWF and Albright College in Reading, Pennsylvania documented near-shore observations of the behaviors of humpback whales in the vicinity of boat activity near an elevated shore-spotting station at Olowalu, Maui.

Observers tracked the movement patterns of individual whales, or pods of whales, using binoculars and a surveyor's transit (theodolite). Whales were observed before, during, and after being approached within .5 mi by one or more boats. Data were collected on repiration intervals, location of boats and whales, and surface behaviors. Thirty-four observation episodes were selected for statistical analysis.

The results indicate that boats had an impact on whale movement and behavior not only while within .5 mi of whales, but also for up to 20 minutes after leaving the area. The observed whales reduced the number of surface behaviors in the presence of boats, engaged in larger changes in direction, and spent more time underwater, when boats were present. After boats left, whales showed evidence of a recovery period, spending significantly longer time under water in the first ten minutes after the boats left, than in the second ten minutes. There was also a gradual recovery of higher frequencies of surface activities.

The study points out the need to consider the cumulative impacts of successive vessels on whales, and the potential importance of a "time out" for the whales following a boat-whale encounter.

©Copyright 1998 Pacific Whale Foundation

NOTE: Euphausiids, also known as "krill", are a taxonomic order of crustaceans, separate from the crustacean order of decapods (Shrimp and Crabs). Krill are a major food source for adult fish, seals, whales, and birds. After Copepods, they are the most important Zooplankton group in the world oceans. Larval and immature fish feed on the smaller juvenile euphausiids. Krill live in the dark, at 100 metres or more by day. Many adults migrate diurnally to the surface at night, to feed on phytoplankton. Most are herbivorous, but some are omnivorous feeders. Two species most likely to be found in Georgia Strait, San Juan Archipelago, and Puget Sound, are Euphausia pacifica and Thysanoessa rachilii. Off the west coast of Vancouver Island the most common are Euphausia pacifica and Thysanoessa spinifera.