SOUTHERN RIGHT WHALES
In recent years, genetic studies have provided clear evidence that the northern and southern populations have not interbred for between 3 million and 12 million years, confirming the status of the Southern Right Whale as a distinct species. More surprising has been the finding that the northern hemisphere Pacific and Atlantic populations are also distinct, and that the Pacific species (now known as the Pacific Northern Right Whale), is in fact more closely allied with the Southern Right Whale than with the Atlantic Northern Right Whale. Whilst Rice listed two species in his 1998 classification this was disputed by Rosenbaum et al (2000) and Brownell et al (2001). In 2005 Mammal Species of the World listed three species, indicating a seemingly more permanent shift to this preference.The right whales are the baleen whales belonging to the family Balaenidae. After many years of shifting views on the number of right whale species, recent genetic evidence has enabled a consensus that there are three right whale species to emerge amongst scientists in the field.
Right whales typically grow to 18 m (60 ft) long and weigh up to 100 metric tons. They are mostly black, very rotund and have distinctive white callosities (skin abrasions) on their head. They are called "right whales" because whalers thought the whales were the "right" ones to catch, since they float when killed. Populations were vastly reduced by intensive harvesting during the most active years of the whaling industry. Nowadays, instead of hunting them, people commonly watch this acrobatic family for pleasure.
Finally, about 7,500 Southern Right Whales are spread throughout the southern hemisphere.
Right whales are easily distinguished from other whales by the large number of callosities on their heads, a thick back without a dorsal fin, and a long dropping mouth that begins high above the eye and the arches round beneath it. The body of the whale is very dark grey or black with some white patches, particularly on the belly. The white patches on the whale's skin around the callosites are not the result of skin pigmentation, but because of large colonies of whale lice.
Right whales have between 200 and 300 baleen plates on each side of the mouth. These are narrow, approximately 2 m long and are covered in very thin hairs. The plates enable the whale to feed (see Diet below). The testicles of the right whale are likely to be the largest of any animal. Each weighs around 500 kg. At 1% of its total body weight, this size is very large even taking into account the size of the whale. This suggests that sperm competition is important in the mating process. Right whales have a distinctive wide-V shaped blow, caused by the widely-spaced blowholes on the top of the head. The blow rises to 5m above the ocean's surface.
Females reach sexual maturity at 6-12 years and breed every 3 to 5 years. Both reproduction and calving take place during the winter months. Calves are approximately 1 metric ton (1.1 short tons) in weight and 4-6 metres in length at birth following a gestation period of 1 year. The right whale grows rapidly in its first year - typically doubling in length. Weaning occurs after eight months to one year and the growth rate in later years is not well understood - it may be highly dependent on whether a child stays with its mother for a second year.
Very little is known about the life span of right whales. One of the few pieces of evidence is the case of a mother Atlantic Northern Right Whale that was photgraphed with a baby in 1935, then photographed again in 1959, 1980, 1985 and 1992, with callosity patterns being used to ensure it was the same animal. Finally in 1995 she was photographed with a seemingly fatal head wound that is presumed to have been caused by a ship strike. The animal was around 70 years of age at death. Research on Bowhead Whales suggest this age is common and may be exceeded.
Right whales are slow swimmers - reaching only 5 knots at top speed - but are highly acrobatic and frequently breach (jump clear of the sea surface), tail-slap and lobtail. The species are not particularly gregarious. The typical group size is two. Larger groups of up to twelve have been reported though even these were not close-knit and may have been transitory. An exception to this rule is when the whales feel threatened by a large shark or killer whale, the species' only predators. In these circumstances the whales may come together in a circle, with their tails pointing outwards, in order to deter the predator. This defence is not always successful and calves are occasionally successfully separated from their mother and killed by drowning.
Sound production and hearing
A report published in the Proceedings of the Royal Society B in December 2003 suggested that Northern Rights responded rapidly on hearing sounds similar to police sirens - sounds of much high frequency than those made by whales. On hearing the sounds they moved rapidly to the surface. The research was of particular interest because it is known that Northern Rights ignore most sounds, including those of approaching boats. Researchers speculate that this information may be useful in attempts to reduce the number of ship-whale collisions..
Hunting of right whales was begun by the Basques as early as the 11th century in the Bay of Biscay. They were replaced by the whalers of the new American colonies, the "Yankee whalers", who were able to take up to 100 right whales in good years. By 1750 the Atlantic Northern Right Whale was as good as extinct for commercial purposes and the Yankee whalers moved on to taking Sperm Whales and into the South Atlantic before the end of the 18th century where they were joined by fleets from several European nations and Japan. By 1937, there had been 38,000 takes in the South Atlantic, 39,000 in the South Pacific, 1,300 in the Indian Ocean and 15,000 in the north Pacific. Given the incompleteness of these records, the actual take was somewhat higher.
As it became clear that stocks were nearly destroyed, a worldwide total ban on right whaling was implemented in 1937. Because the oceans are so large it is very difficult to accurately gauge the size of a whale population. The estimate of 7,000 Southern Right Whales came about following a workshop of a IWC workshop held in Cape Town in March 1998.
Researchers counted used data about number of adult females from three surveys (one in each of Argentina, South Africa and Australia collected during the 1990s) and extrapolated to include unsurveyed areas, number of males and calves using available male:female and adult:calf ratio data to give an estimated 1999 figure of 7,000 animals. Further information may be obtained from the May 1998 edition of "Right Whale News" available online here.
Southern Right Whales spend the summer months in the far Southern Ocean feeding, probably close to Antarctica. Animals migrate north in winter for breeding and can be seen around the coasts of Chile, Argentina, Brazil, South Africa, Mozambique, Australia and New Zealand. The total population is estimated to be 7,000 to 8,000. Since hunting of the Southern Right Whale ceased, stocks are estimated to have grown by 7% a year. It appears that the South American, South African and Australasian groups intermix very little, if at all, because the fidelity of a mother to its feeding and calving habitats is very strong, and is passed from mother to calf.
The Southern Right Whale is protected in the jurisdictional waters of all countries with known breeding populations (Argentina, Australia, Brazil, Chile, New Zealand, South Africa and Uruguay). Southern Right Whales have made Hermanus, South Africa one of the world centers for whale watching. During the winter months (July-October) Southern Right Whales come so close to the Cape shoreline that visitors can watch whales from their (deliberately placed) hotels. The town employs a "whale crier" (cf. town crier) to walk through the town announcing where whales have been seen. Southern Rights can also be watched at other winter breeding grounds.