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:
- they are warm blooded
- they breathe air
- they bear live young and nurse them with milk
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:
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.
Incredible humpback breach off of Maui
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
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 seasafter 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.
Baby common dolphin entangled in driftnet
“Can you see what killed this baby common dolphin?
Neither could she. Driftnets are undetectable on cetacean sonar.”
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 TOOLS FOR TEACHERS
– Ask students to list all the ways that they can think of that whales are similar to humans. Ask them to list all the ways they are different. Repeat the same exercise substituting fish for humans.
– Ask each student to develop a pneumonic device to help them to remember the order of levels used in biological classification (ie., King Philip caught orange fish and green spiders)
– Lead a discussion about adaptive radiation. Ask students to give examples of mammals that live in the air, in the water, and on the land. Ask them to name what adaptations they think the animal has undergone to live successfully in their particular type of habitat.
– Ask students to make a list describing all the ways that toothed whales are similar to baleen whales. Make a second list describing all the ways they are different from one another. In this list, several important differences should have been noted. Why do you think these differences exist?
– Organize and lead a whale watch excursion for your class. There are a number of boating companies that offer sea-going tours on Maui, Oahu, and the Big Island, as well as several excellent land-based vantage points to view the whales during their stay in the islands from November through May.
– Pretend your class is the newly appointed International Whaling Commission (IWC). As a group, draw up a new international treaty which would be used worldwide to conserve whales in the 21st century. Send your recommendations to members of the real IWC in London- let them know what you think! Here’s their address: International Whaling Commission; The Red House; Station Road; Histon, Cambridge CB4 4NP; UNITED KINGDOM.
– Draw a map showing the migration route for Humpback whales from the North Pacific to Hawaii. Have students explain how the whale’s activities change along the migratory route (ie., where whale feeds, where mates, where sings).
– In 1986, an international ban on commercial whaling was agreed to by all whaling nations in order to give depleted whale populations a chance to recover. Some nations are not in favor of the ban and would like to resume commercial whaling. Ask students why they think these nations should or should not be able to resume whaling, and under what conditions.