Desmoilins, 1822 - Southern right whale
Distinctive Characteristics
These stocky whales have extremely large heads, which can be over one-fourth of the body length. The mouthline is bowed and the rostrum is arched and very narrow when viewed from above. As is true for right and bowhead whales in general, there is no trace of a dorsal fin or ridge in the southern right whale. The flippers are fan-shaped, and the flukes are broad with smooth contours. All right whales have callosities on their heads, the largest of which is called the bonnet. These callosity patterns are individually distinctive and have been used by researchers in many areas to identify individuals.
Southern right whales are largely black, but some have white patches of variable shape and size on the belly and sometimes on the back. Colour variants have been noted; these include blue-black, light brown, and nearly white individuals. In addition to those on the callosities, whale lice are common in creases and folds on the bodies of southern right whales.
The 200 to 270 baleen plates per side are narrow and long, up to 3 m in length. The plates tend to be dark grey to black (some can be nearly white) and have fine grey to black fringes. The blow of the southern right whale is relatively short and V-shaped, making this species identifiable at a distance, if seen from ahead or behind.
Can be confused with
The southern right whale is the only whale in its range with a smooth, finless back and callosities; this should make misidentifications unlikely. From a distance the bushy, somewhat V-shaped blows of humpback whales can be mistaken for those of right whales. At close range, the 2 species are unmistakable.
Size
Southern right whale adults reach up to 17 m in length; females grow larger than males. These animals can reach weights of at least 100 t. Newborn animals are 4.5 to 6 m.
Geographical Distribution
Southern right whales are distributed throughout the Southern Hemisphere, from approximately 20°S to 55°S, although they have been observed as far south as 63°S. In winter and spring, the distribution is concentrated near coastlines. Major breeding areas are nearshore off southern Australia, New Zealand, southern South America, and South Africa. A few right whales have been sighted in Antarctic waters in summer.
Biology and Behaviour
Southern right whales have been well-studied on their winter breeding grounds, especially at Peninsula Valdes, Argentina, and in South Africa. Researchers have used callosity patterns to identify individuals on these grounds, and have learned much about the right whale's behaviour, communication, and reproduction. Right whales often seem slow and lumbering, but can be surprisingly quick and active. They often breach, and slap their flippers and flukes on the surface. Southern right whales often raise their flukes on a dive.
Most of the breeding in Argentina takes place in August and September, but mating has been observed in most months of the year. Male right whales have huge testes and long penises, 2 characteristics predicted in species in which males compete for females primarily through sperm competition, rather than by direct aggression.
Surface and subsurface skim feeding is the rule in this species. Southern right whales prey on copepods and krill, apparently sometimes feeding near the bottom.
Exploitation
Southern right whale populations, like their northern counterparts, have been heavily depleted by commercial whaling. Although not as endangered as the northern species, southern right whale populations are still relatively small. Although fully protected by the IWC, there is probably still some hunting for right whales. Despite the threats from whaling, entanglement in fishing gear, vessel collisions, and habitat destruction, some southern right whale populations have shown recent signs of recovery.
IUCN Status
Vulnerable. |
