| Southern right whale[1] | |
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| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Cetacea |
| Family: | Balaenidae |
| Genus: | Eubalaena |
| Species: | E. australis (Desmoulins, 1822) |
| Binomial name | |
| Eubalaena australis |
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| Range map | |
| Synonyms | |
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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.[3][4] Approximately 10,000 southern right whales are spread throughout the southern part of the Southern Hemisphere.
The maximum size of an adult female is 15 m (49 ft)[5] and can weigh up to 47 tonnes (46 long tons; 52 short tons).[5] 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.[6] 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.
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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.[7]
Synonyms for E. australis have included B. antarctica (Lesson, 1828), B. antipodarum (Gray, 1843), E. temminckii (Gray, 1864).[1]
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,[8] Rosenbaum, et al. disputed this in 2000,[9] as did Brownell et al. in 2001.[10] In 2005, Mammal Species of the World listed three species, indicating a shift to this approach.[1] 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.[11]
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.[3]
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 10,000. 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.[7]
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.[13]
Many features are still unknown about right whale populations in New Zealand waters. However, studies by Department of Conservation and sightings reported by locals helped to deepen understanding. Scientists used to believe there was a very small, remnant population of southern right whales inhabiting New Zealand's "main" islands (North and South Island), containing probably 11 reproductive females.[14] In winter, whales migrate north to New Zealand waters and large concentrations occasionally visit the southern coasts of South Island. Bay areas along Foveaux Strait from Fiordland region to northern Otago are important breeding habitats for right whales, especially Preservation Inlet,[15] Te Waewae Bay,[16] and Otago coast.[17] The population at sub-Antarctic Auckland Islands is showing a remarkable recovery.
Recent study revealed that the right whale populations from New Zealand's main islands and the one from sub-Antarctic islands interbreed though it is still unknown whether the two stock originally came from a single population.[18] Some whales can be seen at Campbell Islands, too.
In Brazil, more than 300 individuals have been cataloged through photo identification (using head callosities) by the Brazilian Right Whale Project, maintained jointly by Petrobras (the Brazilian state-owned oil company) and the International Wildlife Coalition. The State of Santa Catarina hosts a concentration of breeding and calving right whales from June to November, and females from this population also calve off Argentinian Patagonia and Uruguay.
By 1750 the North Atlantic right whale was as good as extinct for commercial purposes and the Yankee whalers moved into the South Atlantic before the end of the 18th century. The southernmost Brazilian whaling station was established in 1796, in Imbituba. Over the next one hundred years, Yankee whaling spread into the Southern and Pacific Oceans, where the American fleet was joined by fleets from several European nations.
The Southern right whale had been coming to New Zealand waters in large numbers before the 19th century, but was extensively hunted from 1830-1850. Hunting gradually declined with the whale population and then all but ended in coastal New Zealand waters.[19] The beginning of the 20th century brought industrial whaling, and the catch grew rapidly. By 1937, according to whalers' records, 38,000 were captured in the South Atlantic, 39,000 in the South Pacific, and 1,300 in the Indian Ocean. Given the incompleteness of these records, the total take was somewhat higher.[20]
As it became clear that stocks were nearly depleted, right whaling was banned in 1937. The ban was largely successful, although some illegal whaling continued for several decades. Madeira took its last two right whales in 1968. Illegal whaling continued off the coast of Brazil for many years and the Imbituba station processed right whales until 1973. The Soviet Union admitted illegally taking over 3,300 during the 1950s and '60s,[21] although it only reported taking 4.[22]
Whales began to be seen again in Australian and New Zealand waters from the early 1960s.[19]
The southern right whale, listed as "endangered" by CITES, is protected by all countries with known breeding populations (Argentina, Australia, Brazil, Chile, New Zealand, South Africa and Uruguay). In Brazil, a federal Environmental Protection Area encompassing some 1,560 km2 (600 sq mi) and 130 km (81 mi) of coastline in Santa Catarina State was established in 2000 to protect the species' main breeding grounds in Brazil and promote regulated whale watching.[23]
The Southern right whale is listed on Appendix I[24] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS) as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range.
The Southern right whale is covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).
Kelp gulls have been observed feeding on live southern right whales since at least 1996 off the coast of Patagonia.[25] The kelp gull uses its powerful beak to peck down centimetres into the skin and blubber, often leaving the whales with large open sores, some of which have been observed to be half a meter in diameter. This predatory behavior has been continually documented in Argentinian waters, and continues today. It is thought that open garbage pits that provide food for gulls contribute to an overpopulation of gulls. [26]
The southern right whale has made Hermanus, South Africa one of the world centers for whale watching. During the winter months (June to November), southern right whales come so close to the shoreline that visitors can watch them from strategically placed hotels. Hermanus also has two boat–based whale watching operators. The town employs a "whale crier" (cf. town crier) to walk through the town announcing where whales have been seen. Southern right whales can also be watched at other winter breeding grounds.
In Brazil, Imbituba in Santa Catarina has been recognized as the National Right Whale Capital and holds annual Right Whale Week celebrations in September, when mothers and calves are more often seen. The old whaling station there is now a museum that documents the history of right whales in Brazil. In Argentina, Península Valdés in Patagonia hosts (in winter) the largest breeding population, with more than 2,000 catalogued by the Whale Conservation Institute and Ocean Alliance.[27] As in the south of Argentina, the whales come within 200 m (660 ft) of the main beach in the city of Puerto Madryn and form a part of the large ecotourism industry.
In Australia's winter and spring, southern right whales can be seen from the Bunda Cliffs and Twin Rocks, both along the remote Great Australian Bight in South Australia.[3] In Warrnambool, Victoria, there exists a nursery which is popular with tourists in the winter and spring.