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Great Whales

The whales referred to as "great whales" include all of the baleen whales and one toothed whale, the sperm whale. Great whales range in size from the 30-foot minke whale to the 100-foot blue whale.

Baleen whales do not have teeth—they have plates made of a material similar to human fingernails (baleen) that hang down from the roofs of their mouths. These plates, fringed at the ends, are used to comb large amounts of water (and sometimes mud) for small creatures of numerous species, together known as zooplankton, as well as small fish. The blue whale, not only the largest baleen whale but also the largest creature ever to have lived on earth, feeds almost exclusively on a tiny, shrimp-like creature called krill.

The great whales have been the targets of aboriginal and commercial whalers for many centuries. Their blubber was rendered into oil, their meat eaten, and their baleen used, as a precursor to plastic, in corsets, umbrellas, and other items.

Sperm Whales

Sperm whales, on which Herman Melville's Moby Dick was modelled, were hunted primarily for their oil, not only from their blubber but also from their spermaceti organ. This organ, found in the sperm whale's prominent forehead and apparently used as a lens to focus the loud clicks and other sounds the whale makes, is filled with an oil that humans once used to lubricate fine watch works and other intricate devices. Sperm whale teeth were also used for scrimshaw art.

Blue, Fin, Minke, and Humpback

The family Balaenopteridae includes species such as the blue, fin, minke, and humpback whales. These species are distinguished by their streamlined shapes, their speed, their medium-length baleens, and their throat grooves, which are accordion-like pleats that expand the animal's throat when it takes in a large amount of water to filter through its baleen. These species undertake long migrations between polar feeding grounds and temperate and equatorial birthing grounds.

Northern Right, Southern Right, and Bowhead

The family Balaenidae includes the northern and southern right whales and the bowhead whale. These whales are distinguished by their huge heads (which allow them to take in large mouthfuls of water without having to expand their throats), their very long baleens, their slow swimming speeds, and their lack of prominent dorsal fins. The bowhead is exclusively Arctic in its distribution, while the right whales undertake migrations.

Gray

The family Eschrichtiidae has one species, the gray whale. Gray whales are bottom feeders, scooping up huge mouthfuls of mud to filter out tiny crustaceans. This species undertakes the longest known migration of any whale: a 10,000-mile annual round trip between the Bering Sea (Arctic) feeding grounds and Baja California Sur birthing lagoons.

Social Structure

The most stable social grouping in baleen whales is a mother and her calf. However, they also tend to gather in small, transient groups on their rich feeding grounds or in protected mating and birthing areas. The sperm whale, however, has a complex social structure: Females live in large groups, raising their young communally, while males form "bachelor herds," migrating far greater distances than females and joining the nursery groups only during the mating season. The great whales give birth to one calf at a time, usually every other year, although in some species the interval between births is longer.

Populations

Most of the great whales are endangered. Some species such as the northern right whale and the blue whale were decimated by commercial whalers and, because of habitat degradation and other human-caused factors, have not been able to recover. Some populations such as western gray whales and eastern bowhead whales number precariously few, and may also be in danger of extinction.

Right Whales

According to the most recent population assessments, only about 300 North Atlantic right whales still inhabit the waters off the east coast of the United States and Canada. Until the early 1990s, the population showed slow signs of recovery. However, recent studies indicate that the survival rate of right whales declined significantly in the past decade, meaning the population is now sliding toward extinction.

Doomed to Extinction

A 1999 report from the Proceedings of the National Academy of Science concluded that, under current conditions, "the population is doomed to extinction," and that the last right whale will die with no descendants within 200 years. The primary risks for right whales are entanglement in commercial fishing gear and collisions with ships. Reducing human-caused mortality is essential to the continued existence of the North Atlantic right whale.

The annual stock (population) assessment by the American National Marine Fisheries Service (NMFS) identifies reduced reproduction as another major factor in the right whale's declining population. The mean interval between births has increased from an average of one calf birth every 3.67 years in 1992 to a current average of over five years between calf births. Observers saw only one calf in the 2000 calving season, but some good news came during the past calving season, when 30 new calves were born. This does not mean recovery is now in sight. A single good year in over a dozen poor years is hopeful, but we do not yet know what upcoming years will bring. And at least two of these calves have already died as a result of the many threats faced by right whales.

Human-Caused Mortalities

A workshop conducted by the International Whaling Commission (IWC) Scientific Committee agreed with American scientists that entanglement and ship collision were significant causes of right whale mortality, and it noted with "grave concern" the decline of this critically endangered population. The IWC workshop also accorded the "highest priority" to measures that would immediately reduce mortality from entanglements and ship collisions. The workshop report, presenting the considered opinion of several of the foremost researchers on right whales, "strongly emphasizes there is no need to wait for further research before implementing any currently available actions that can reduce [human-caused] mortalities."

Entanglement

The entanglement of right whales in commercial fishing gear has been documented for more than three decades. Right whales may become entangled in nets, in the lines between nets, or in buoy lines that go to the surface, and may drown if unable to reach the surface to breathe. Entanglement can also impair movement, making them more vulnerable to ship collisions or unable to eat properly, risking starvation. Fishing gear that is swallowed by or wrapped around a whale may also seriously injure the animal ("serious injury" is a legislative term that refers to injuries that may lead to death).

Whales may even become entangled multiple times. One right whale was entangled in commercial fishing gear once in late 1997, and two more times in 1998, before being freed of most of the gear; however, fishing gear remains in the whale's mouth. This whale, considered "seriously injured," has not been seen since 1998. A number of other whales were entangled in 1999 and 2000, including one whale found floating dead near Rhode Island in 2000, but the status of each whale (whether or not the animal has been seriously injured) has not yet been determined. One right whale was found floating dead early in 2001, with fishing gear wrapped around its tailstock, although the carcass was not recovered and cause of death remains undetermined at this time.

Collisions with Ships

Collisions with ships have also occurred for many decades. As we look more closely for the cause of death in right whales, we're discovering that ship collisions play a greater role than previously thought. Right whales are slow moving whales who migrate through, and live in, coastal waters near busy ports. This has resulted in collisions with large ships, often leading to the death of the whale. Since 1995, at least eight right whales have been killed in such collisions. In 2001 alone, two of the calves born to the population were killed by ships. Their lacerated bodies were found near the mid-Atlantic area of the United States, along the route they use to migrate north with their mothers.