I. BIOLOGY AND NATURAL HISTORY
Although their general shape resembles that of a fish, humpback whales are
mammals just like humans, and exhibit a number of traits common to
all mammals including the following:
Like all whales and dolphins, humpback whales belong to the order cetacea.
An order is the fourth level used in biological classification. Biological
classification is the method by which all living organisms are scientifically
named and classified. The science of biological classification is called
taxonomy. There are seven levels of biological classification, the
remaining levels are listed below:
Kingdom
Phylum
Class
Order
Family
Genus
Species- contains those organisms most closely related; the basic unit of taxonomy
Living organisms are classified largely on the degree of evolutionary relatedness
which they share, as well as their anatomical and biochemical similarities.
The degree of evolutionary relatedness increases as you progress down the
list; members of the same kingdom are not necessarily as closely related
as members of the same species. A species possesses those organisms which
are the most closely related and is considered the basic unit of taxonomy.
Every living organism is given a species name and a genus to which it belongs.
Naming organisms by genus and species is universally employed throughout
biology and allows scientists to communicate effectively about specific
organisms. Assigning each organism a genus and species name is referred
to as binomial nomenclature, which means "two names," just
like most of us have two names. In addition, several of the levels can be
broken down further into subcategories such as sub-class,
sub-order and subspecies.
The biological classification for humpback whales is the following:
Kingdom Animalia Phylum Cordata (vertebrates) Class Mammalia (mammals) Order Cetacea Sub-order Mysticeti (baleen whales) Family Balaenopteridae Genus Megaptera Species novaeangliae
All members of the order cetacea are believed to have evolved from terrestrial
hoofed mammals like cows, camels and sheep some 45 million years ago - that's
about 40 million years before man! Throughout their evolution, cetaceans
have become perfectly suited to an aquatic environment, and are virtually
incapable of leaving it. Cetaceans illustrate an example of adaptive
radiation among mammals. Adaptive radiation allows mammals as a group
to effectively inhabit the land, the sea, and the air through the development
of special adaptations needed to survive in each of these environments.
Members of the order cetacea have undergone a number of changes or adaptations
needed to fare well in their watery home: their bodies have become streamlined
for efficient movement through the water; their forelimbs have been modified
into flippers which aid them in steering; their hind limbs have disappeared
almost completely; their tail has become broadened horizontally and consists
of two large flukes which propel them powerfully through the water
by moving up and down, rather than side to side like a fish; in place of
hair they have developed a thick layer of fat called blubber under
their skin that insulates them from the cold and provides buoyancy ; and
the position of their nostrils has shifted to the top of their head creating
a blowhole that allows them to effectively come to the surface for
air. A whale's blowhole generally reaches the surface before the rest of
its body.
In addition, a number of other changes have taken place to help whales adapt
to life in the sea. Many of these changes are related to the position and
abilities of their sensory organs, as life in the water is not the same
as life on the land. Sound and light travel differently in water than they
do in the air. As a result, whales have developed unique ways of hearing
and seeing. Hearing in particular is highly developed in whales, so much
so that they depend on it in the same way that we depend on the combination
of our eyes, ears and nose to understand the world around us (see section on dolphins for additional information). Many
of the whale's sensory and reproductive organs have been internalized to
reduce drag while swimming. For example, whales do not have external ears,
but rely on an internal system of air sinuses and bones to detect sounds.
Changes in their reproductive and parental behaviors have also taken place,
enabling whales to provide optimum care for their young in the cold, large
ocean. Along with these differences, cetaceans do, however, possess many
of the same physiological systems - circulatory, digestive, respiratory,
and nervous as the land mammals from which they evolved. For instance, many
species possess multi-chambered stomachs even though there is no obvious
advantage to having such an arrangement as whales do not chew cud!
The order cetacea can be further divided into 2 sub-orders based largely
on the type of food eaten and structures used to eat it with. Food is an
important component of an animal's ecosystem, as it is a limited resource,
meaning there is only so much of each kind of food to go around. Other limited
resources in the whales ecosystem include space, or territory, and mates.
Whales need to eat a lot, as they are mammals and need to maintain a warm
body temperature while living in the cold ocean. This fact, combined with
their large size, make the daily food requirements for whales quite high.
Their enormous need for food has brought about the development of unique
physiological and behavioral characteristics among the different types of
whales. This helps to ensure that each of the different species of whales
gets enough to eat. The ability of cetaceans to undergo adaptations to utilize
different types of foods, allows greater numbers of them to share the same
habitat. The two living orders of cetaceans are the baleen whales
or mysticetes and the toothed whales or odontocetes.
Baleen whales - mysticetes, include whales such as the humpback,
gray and blue whales. Their primary distinguishing characteristic is the
fact that all adults lack teeth, which have been replaced by a series of
baleen plates on either side of their jaw. Baleen, also known as
"whalebone" is not really bone, but is made of keratin,
the same protein substance as our own hair and nails, and the horns of cattle.
Some species have over 400 baleen plates; each less than 1/5 of an inch
thick. The plates are fringed with hairs along their inner edges and descend
like curtains in two rows from the upper jaw. It may help to remember the
two different types of whales by knowing that the scientific name for baleen
whales, mysticetes, comes from the Greek word mystax which means mustache!
Baleen whales feed by opening their mouths and taking in large quantities
of water- as much as 500 gallons at a time. The baleen plates serve as a
strainer. Water filters through and the whale's food which includes small
fish such as herring and mackerel and krill, a tiny shrimp-like organism,
is filtered out as it is trapped in the hairy fringes of the plates. The
whale then uses its large rasping tongue to remove its food and swallows
its meal, filtering the water through its baleen and expelling it out of
its mouth. Baleen whales consume between 2000 and 9000 pounds of fish and
krill a day! They do not feed all year round, however, but only during half
of the year when they are in the cold, nutrient-rich waters of their summer
feeding grounds. Approximately 25% of what they eat during the summer is
stored in the form of fat to provide extra energy and insulation during
their winter fast when they migrate to warmer waters.
The second sub-order of cetaceans are the toothed whales- odontocetes,
which includes the majority of whale species such as sperm whales (like
"Moby Dick",) killer whales, dolphins, porpoises and many others.
As their name implies, toothed whales have teeth and use them to selectively
capture and eat individual prey. Interestingly, unlike many mammals, toothed
whales do not have "baby" teeth, but develop a single set, none
of which are ever replaced. They are all carnivores, feeding on fish, squid,
and other marine animals. The daily consumption of toothed whales ranges
between 5 and 20 per cent of their body weight. Toothed whales feed all
year round and do not typically migrate.
In addition to methods of feeding, toothed and baleen whales also differ
with respect to the type of blowholes they possess. The blowholes of baleen
whales have two openings, while those of toothed whales have only a single
opening. When whales come to the surface to breathe, air is expelled from
the blowhole as condensation and appears like a cloud of mist above the
ocean surface. It was this cloud of condensation which enabled whalers to
spot whales and led to the famous "Thar she blows!" decree. The
shape, direction, and height of this condensation, known as the spout,
vary among baleen and toothed whales. The double blowhole of the baleen
whale creates a characteristic v-shaped spout, and that of the toothed whale
a single spout pointed diagonally forward.
Now that you have a basic understanding of the different types of whales,
let's take a closer look at one of Hawaii's favorite cetacean visitors-
the humpback whale.
II. A CLOSER LOOK AT HAWAII'S HUMPBACKS
Humpback whales are very large animals. Adults typically range in size from
35 to 48 feet, and weigh in at about one ton per foot. Their scientific
name is Megaptera noveangliae. This means "giant wings",
which refers to their large front flippers that can reach a length of 15
feet-- about one-third of the animal's entire body length. Humpback whales
are found in all of the world's oceans, although they generally prefer near
shore and near-island habitats for both feeding and breeding. The current
world population for the species is estimated to be between 5,000 and 7,500
individuals, and can be divided into groups based on the regions in which
they live. One group found in the North Pacific in the waters off Alaska
is estimated to consist of about 2,000 individuals. A large percentage of
this population are the ones with which you are probably most familiar,
as they migrate to the main Hawaiian islands during the winter months, November
through May, each year. The round-trip distance they travel during this
annual migration is approximately 6,000 miles, one of the longest migration
distances of any animal species. During their stay in Hawaii, they do not
feed, but rely upon energy stored in their blubber. Instead of feeding,
the whales devote most of their time to mating and bearing their calves.
(Fig. 4, Migration route of North Pacific Humpback Population)
Humpback whales become reproductively mature when they are between 4 and
8 years of age. As mentioned, they mate during their winter migration to
warmer waters, and eleven to twelve months later, upon their return to winter
breeding grounds, the mother gives birth to a single calf. At birth,
calves are approximately 13 feet long and weigh two tons. This changes quickly
however, as the mother must feed her newborn about 100 pounds of milk each
day for a period of five to seven months until it is weaned. After weaning,
the calf has doubled its length and has increased its weight five times,
attaining a size of about 27 feet and 10 tons. Usually, a female humpback
will bear one calf every two or three years. The maximum rate of reproduction
for the species is one calf per year, but this is seldom practiced as it
puts quite a strain on the mother whale. Scientists estimate the average
life span of humpbacks in the wild to be between 30 and 40 years, although
no one knows for certain.
While visiting the islands, humpbacks have become renowned for their various
acrobatic displays. In fact, the common name "humpback" refers
to the high arch of their backs when they dive. One of the humpback's more
spectacular behaviors is the breach. Breaching is a true leap where
a whale generates enough upward force with its powerful flukes to lift approximately
two-thirds of its body out of the water. A breach may also involve a twisting
motion, when the whale twists its body sideways as it reaches the height
of the breach. Researchers are not certain why whales breach, but believe
that it may be related to courtship or play activity. Some behaviors such
as headlunging, which occurs when one whale thrusts its head forcefully
towards another whale in a threatening manner, are believed to be aggressive
behaviors meant to ward off competitors. Males display this behavior most
often to gain access to females. Many other behaviors including fluke slaps,
flipper slaps, and headslaps have also been characterized, although their
apparent functions are unknown.
Another interesting behavior exhibited by the humpbacks during their
stay in the islands is singing. The "songs" of humpbacks are made
up of complex vocal patterns. All whales within a given area and season
seem to use the same songs. However, the songs appear to change from one
breeding season to the next. Scientists believe that only male humpbacks
sing. While the purpose of the songs is not known, many scientists think
that males sing to attract mates, or to communicate among other males of
the pod.
A Pod refers to a social group of whales. In Hawaii, humpback whales
typically belong to pods consisting of 2 to 3 individuals, although pods
as large as 15 individuals have been sighted. Scientists feel that whales
belong to certain pods for relatively short periods of time. One type of
pod that is especially interesting is the cow-calf pod. A cow-calf pod represents
the longest association between individual whales. In this type of pod the
mother whale, the cow , remains with her calf for a year during which time
she nurses the young whale. In may instances, cow-calf pods are accompanied
by another adult known as an escort. Escorts can be of either sex, but are
most often reported to be males. Escorts do not remain in the cow-calf pod
for long periods of time, usually for only a few hours. There have been
no reported sightings of whale pods which contain more than one calf, indicating
that each young whale is given a great deal of individual attention and
care. This fact, together with the fact that the normal breeding-cycle of
a humpback whale is two years, helps to explain why the recovery of the
humpback whale population is progressing so slowly.
III. FACTORS AFFECTING HUMPBACK WHALE POPULATIONS
A. Whaling
Largely because of their tendency to frequent coastal waters, and their
habitual return to the same regions each year, humpback whales have been
exploited by commercial whalers all around the world. Humpbacks were hunted
for their oil, meat and whalebone. Most populations were drastically reduced
in the early part of the 19th century, leaving only between 5 and 10 per
cent of the original stock remaining. In the North Pacific, it is estimated
that as many as 15,000 humpbacks existed prior to 1900. The population was
truly decimated to fewer than 1,000 individuals before an international
ban on commercial whaling was instituted in 1964. Today, the North Pacific
population which returns to Hawaii in the winter months to breed, now numbers
approximately 2,000. In spite of their recent strides towards recovery,
humpbacks continue to be designated as an endangered species. Only the right
whale, another species of baleen whale, is considered more endangered than
the humpback in the North Pacific.
No one knows whether whales were present in ancient Hawaiian times in similar
numbers as occur here today. Information related to whales in Hawaiian history
is scanty. Lack of evidence about the presence of whales in Hawaii before
Captain Cook's discovery of the islands in 1778, suggests that whales either
played a minor role in ancient Hawaiian culture, or that their appearance
in Hawaiian waters is one of recent migration. Some scientists believe that
humpbacks first migrated to Hawaii as little as 200 years ago as a result
of whaling pressures in other regions. Others believe that humpbacks had
difficulty finding the islands because they are so far away from any other
land masses, or that changes in oceanic habitats may have occurred, making
Hawaii a more attractive destination. No one knows for certain.
One thing that is known for certain is that Hawaii was a central whaling
port in the Pacific for more than 40 years. From 1820 into the 1860's, the
islands served as an important port to the whaling ships of the North Pacific.
Twice a year, Hawaii provided a place for the whaling ships to come and
restock their provisions, transship their oil and whalebone, and provide
respite for their weary crews. Both Lahaina and Honolulu prospered tremendously
as millions of dollars were thrust freely into the island economy. The whaling
industry created economic growth and jobs in Hawaii as had never been experienced
before.
A Look at Whaling Today
Since the 1800's, much about whaling has changed. Not only did the methods
of how the whales were hunted change, but also the way in which the whaling
industry was managed.
Beginning in the mid-1800's, whalers made use of technology that was not
available in the early whaling days. In many ways this modern technology
seemed to make the fight between the whaler and the whale much less fair.
It included the use of ships that were bigger, faster and capable of chasing
and killing the larger, faster whales. In addition to being bigger and faster,
these ships were later aided by new technologies for locating whales such
as underwater sonar, spotter planes and helicopters that were a far cry
from a lookout clutching the mast and scouting the horizon for whale spouts.
The weaponry used to kill the whales was also more effective. The lone harpooner
braced on the bow of a rocking whaleboat was replaced by guns that fired
barbed harpoons that exploded when embedded in the whale. These explosive
harpoons caused the whale to suffer a painful death which sometimes took
as long as two hours. Millions of whales were killed with these new harpoons
and then hauled aboard a factory ship where they could be "processed"
in less than an hour and turned into raw materials for products including
shoe polish, dog food, margarine and tennis racket strings. The new technologies
used in modern whaling were responsible for bringing about the drastic population
reductions experienced by many whale populations- including the humpbacks.
In 1946, an international committee, the International Whaling Commission
(IWC) was established to oversee management of the whaling industry
worldwide and to provide for the conservation of whales so that they "may
be safeguarded for future generations." Membership to the Commission
was open to all of the whaling nations of the world. The IWC operated according
to guidelines set forth in the International Convention for the Regulation
of Whaling, a formal agreement developed at the time the Commission was
established. The Convention imposed regulations for hunting species of whales
determined to need protection and set open and closed seasons and waters
. In its first twenty years the IWC concentrated heavily on managing the
business aspects of whaling. It was not until the 1960's, following the
depletion of several major whale populations, including those of the humpback
and blue whale, that the IWC expanded its role to include a strong conservation
ethic.
In 1986 the IWC instituted a 10 year moratorium, or complete ban,
on commercial whaling to properly determine the status of whale populations
and give depleted populations an opportunity to recover. Since the moratorium
went into effect, several pro-whaling nations including Iceland, Norway
and Japan have expressed their dissatisfaction over the moratorium as they
wish to continue hunting some species of whales as a source of food and
oil. Some of these nations have withdrawn or have threatened to withdraw
from the IWC, while others are no longer honoring the moratorium. At least
14,000 whales have been killed since the moratorium took effect. In 1992,
more whales were killed than in any year since the moratorium's passing.
This illustrates the fact that the moratorium on commercial whaling is being
weakened.
Presently under the IWC Convention two types of whaling are legally permitted.
These two types are: 1) subsistence whaling, or the taking of a limited
number of whales by certain indigenous , or native peoples, for their
own use, and 2) scientific whaling which refers to the regulated
taking of whales that are not considered to be threatened or endangered
for the purpose of furthering our knowledge about whales.
In contrast, there are two types of whaling that are not legally permitted
under the moratorium, but continue to be practiced by members of some nations
despite the international ban. These are 1) pirate whaling which
is the non-regulated, illegal taking of whales and 2) commercial whaling
which is the taking of whales for commercial sale. The main motive behind
both these types of whaling is the potential to make large sums of money.
For instance, in Japan whale meat is a delicacy commanding prices of more
than $100 per pound. Such profits provide economic incentive for pro-whaling
nations to have the moratorium on commercial whaling lifted, and to have
the quotas on scientific whaling increased, as many of the whales hunted
under the guise of scientific research mysteriously find their way into
the commercial markets.
Whales face several threats other than the resumption of commercial whaling.
These include entrapment in high seas driftnets, pollution and degradation
of their habitat. Each of these issues is addressed briefly below.
B. Driftnets and Coastal Gill nets
Another human activity that poses a serious threat to the humpbacks as well
as other species of whales is driftnet fishing. Driftnets are huge
nets made of lightweight nylon which measure between 1.25 to 90 miles in
length and 8 and 15 feet in depth. They are left to "drift" in
the open ocean for periods of 8 hours or more, hence the name "driftnet".
While driftnets are an effective means of catching their target species,
the species they are intended to catch- generally tuna and squid, they are
an indiscriminate method of fishing, and tend to entrap anything
larger than their mesh size. This includes sea birds, turtles, seals, dolphins,
whales and many species of non-target fish which together are known as the
by-catch. The majority of the animals that become entangled in driftnets
are not able to free themselves and drown. Thousands of whales, dolphins,
sea birds and turtles, many of which are endangered, die needlessly in driftnets
each year.
Large-scale driftnet fishing has often been referred to as "the most
deadly and wasteful fishing method ever developed." Driftnets deplete
fish populations so completely that many times there are few fish remaining
for fishermen who use more sustainable methods. Driftnet fishing
is also extremely wasteful. Thousands of tons of fish drop out of the nets
or are discarded when the nets are hauled in. Estimates of spoiled target
catch and discarded by-catch vary between 17% and 55% of the total.
In 1991, the United Nations passed a resolution establishing an international
moratorium on high seas driftnet fishing, effective January 1993. The driftnet
moratorium makes it unlawful to set driftnets anywhere on the high seas
after this date. While it is an important victory for conservationists and
marine wildlife around the world, it is important that the driftnet moratorium
be properly enforced in order for it to be effective. This may require that
a system to carefully monitor the high seas and report any driftnet activity
be developed. Needless to say, establishing such an observation system could
prove to be quite difficult and presents a number of challenges to those
involved with fisheries conservation.
In comparison, coastal gill nets are used primarily by artisenal,
or non-commercial fishermen. Gill nets are smaller in size and can either
be anchored on the sea bed or allowed to drift. The use of gill nets has
been rapidly increasing around the world without any control or monitoring.
Although they are an efficient method of catching fish, they are also leading
to the population decline of several species of fish, as well as the deaths
of many other marine animals each year. The whales, dolphins, sea turtles
and other species most at risk from the use of gill nets are those that
live close to shore. Gill nets are commonly used by fishermen around the
main Hawaiian islands.
In the spring of 1993, new laws went into effect that regulate the use of
gill nets in Hawaiian waters. It is now unlawful for any person fishing
with a gill net to leave the net unattended for more than two hours without
visually inspecting the net and releasing undersized, illegal or unwanted
catch. It is also illegal to leave any gill net in the water for a period
of more than four hours in a twenty-four hour period.
C. Marine Pollution
While the overall impact of pollution on the marine environment is unknown,
contaminants introduced by rivers, coastal runoff, ocean dumping and various
other activities are beginning to take their toll on the oceans. More than
80% of all marine pollution originates from land-based sources which are
primarily industrial, agricultural and urban. Whale populations are coming
under increasing stress from pollution, eutrophication and polychlorinated
biphenyl (PCB) contamination.
PCBs are one of many man-made chemicals used in the production of plastics
and styrofoams- common components of beach trash. Mass die offs of cetaceans
thought to be related to PCBs and other environmental factors have been
increasing in the last decade. For instance, an increasing number of deaths
of Beluga whales (a species of white whale found predominantly in northern
latitudes) have been associated with pollutants like PCBs. In many instances,
the concentration of PCBs found in the tissue of Beluga whales is so high
that their corpses are considered to be hazardous waste and must be handled
as such. Accumulation of PCBs in the tissue of whales is also thought to
alter their physiology and in turn, reduce their ability to reproduce.
Ozone depletion brought about by the burning of fossil fuels, such as oil
and gasoline, is also thought to be indirectly harmful to whales. This is
particularly true in the southern hemisphere where ozone depletion has resulted
in increased levels of ultra-violet B radiation (UV-B) reaching the earth's
surface. UV-B is known to have significant negative biological effects on
phytoplankton, the species of marine algae which form the basis of
the marine food chain, and krill, a diet staple for many species of baleen
whales. By limiting the consumption of fossil fuels, we can actually help
protect the whale's ecosystem by keeping the food chain intact. Greater
protection of the world's oceans, seas and rivers is vital to provide a
livable habitat for whales and other marine species.
D. Whale Watching
Not all of man's actions towards the whales are harmful. One way man has
chosen to take advantage of the whales is to enhance his understanding and
appreciation of them through whale-watch cruises and other types of eco-tourism.
Eco-tourism is a non-consumptive method of "using" wildlife
species to make a profit without directly harming or killing them.
Increasingly, many nations of the world have come to realize that living
whales have more economic value as marine resources than they do on a dinner
plate. In many places, including Hawaii, whale-watching has become a lucrative
business. The whale- watch industry draws almost one million visitors to
Hawaii each year, resulting in tourist income for the state of more than
80 million dollars annually. Other nations including Norway, which has expressed
a strong interest in resuming commercial whaling, are launching whale-watch
programs and noting their successful results.
IV. PROTECTIVE MEASURES
A. Federal Laws and Regulations
In the United States all species of whales, including the humpbacks, are
protected by two federal laws. They are 1) the Marine
Mammal Protection Act of 1972; and 2) the
Endangered Species Act of 1973. (See Appendix
2 for more detail of these laws.)
In addition, there are specific regulations on approaching humpback whales
in Hawaiian waters. These regulations are meant to ensure that humpback
whales are not disturbed or harassed in the course of human activities.
These regulations are listed below.
It is unlawful to:
1. Operate any aircraft within 1,000 feet of a humpback whale
2. Approach by any means (ie., by boat or by swimming) closer than 100 yards of any humpback whale or closer than 300 yards of a humpback mother and calf.
3. Disrupt the normal behavior or activity of a humpback whale. This is considered a form of harassment.
Violators of these regulations may be prosecuted by the Federal government
and may be subject to penalties of up to $25,000 for each violation or penalty.
If you witness an incident or suspect a violation of any of these laws or
regulations, you are encouraged to contact the law enforcement office of
the National Marine Fisheries Service at (808) 541-2730.
B. International Protection
Outside the United States, populations of the humpback and other species
of whales are protected from hunting under agreements made by the International
Whaling Commission (IWC), as mentioned above.
In addition, protection against the pressures of international trade is
provided by the Convention on International
Trade in Endangered Species of Wild Fauna and Flora (CITES). CITES is
an international treaty that protects whales as well as other endangered
species by prohibiting trade in their parts or products. 120 nations, including
most wildlife consuming and producing nations, have signed the treaty and
have agreed to abide by its provisions. (See Appendix
2 for further detail)
[Suggested Activities for the Teacher Utilizing
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