Southern Right Whales

The Southern Right Whale (Eubalaena australis) is a baleen whale, one of three species classified as right whales belonging to the genus Eubalaena. Like other right whales, the Southern Right Whale is readily distinguished from others by the callosities on its head, a broad back without a dorsal fin, and a long arching mouth that begins above the eye. Its skin is very dark grey or black, occasionally with some white patches on the belly. The right whale's callosities appear white due to large colonies of cyamids (whale lice). It is almost indistinguishable from the closely related North Atlantic and the North Pacific Right Whales, displaying only minor skull differences. It may have fewer callosities on its head and more on its lower lips than the two northern species. Approximately 12,000 Southern Right Whales are spread throughout the southern part of the Southern Hemisphere.

The maximum size of an adult female is 18.5 m (61 ft) and can weigh up to 80 tonnes (79 LT; 88 ST).  The testicles of right whales are likely to be the largest of any animal, each weighing around 500 kg (1,100 lb). This suggests that sperm competition is important in the mating process.

Right whales cannot cross the warm equatorial waters to connect with the other (sub)species and (inter)breed: their thick layers of insulating blubber make it impossible for them to dissipate their internal body heat in tropical waters.

Taxonomy

The Southern Right Whale was initially described as Balaena australis by Desmoulins in 1822. It has been reclassified repeatedly, most recently as a species separate from the other right whales, and may be reclassified again into its original genus because scientists now find greater differences among the three Balaenoptera species than between the Bowhead Whale, the only current member of Balaena, and the right whales. All four species may be placed in one genus in a future review.

Synonyms for E. australis have included B. antarctica (Lesson, 1828), B. antipodarum (Gray, 1843), E. temminckii (Gray, 1864).

Three species theory

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 that the Southern Right Whale is a distinct species. More surprising is the finding that the northern Pacific and Atlantic populations are also distinct, and that the Pacific species (now known as the North Pacific Right Whale) is more closely related to the Southern Right Whale than to the North Atlantic Right Whale.

While Rice continued to list two species in his 1998 classification, Rosenbaum, et al. disputed this in 2000. and Brownell et al. (2001). In 2005, Mammal Species of the World listed three species, indicating a shift to this approach. The communities first split because of the joining of North and South America. The heat of the equator then separated them further into northern and southern groups.

"Whale lice", parasitic cyamid crustaceans that live off skin debris, offer information through their own genetic patterns. Lice genetic diversity is greater than whales' because lice reproduce more quickly. Marine biologists at the University of Utah examined lice genes and determined that their hosts split into three species 5–6 million years ago, and that these species were equally abundant before whaling began in the 11th century.

"This puts an end to the long debate about whether there are three [Eubalaena] species of right whale. They really are separate beyond a doubt," said Jon Seger, the project's leader.

Behavior

One behavior unique to the Southern Right Whale, known as sailing, is that of using their elevated flukes to catch the wind. It appears to be a form of play and is commonly seen off the coast of Argentina and South Africa.

Population and distribution

The Southern Right Whale spends summer in the far Southern Ocean feeding, probably close to Antarctica. It migrates north in winter for breeding and can be seen by the coasts of Argentina, Australia, Brazil, Chile, Namibia, Mozambique, Peru, Tristan de Cunha, Uruguay, Madagascar, New Zealand and South Africa. The total population is estimated to be around 12,000. Since hunting 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 maternal fidelity to feeding and calving habitats is very strong. The mother also passes these choices to her calves.

The most recent population estimates, published by National Geographic in October 2008, put the southern whale population at 10,000. The estimate of 7,000 followed a March, 1998 IWC workshop. Researchers used data about adult female populations 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 ratios to give an estimated 1999 figure of 7,500 animals.