Lissodelphis peroni

31.

Southern Right-whale Dolphin

Lissodelphis peroni

French: Dauphin de Péron / German: Sidlicher Glattdelfin / Spanish: Delfin sin aleta meridional

Other common names: Mealy-mouthed Porpoise, Peron’s Dolphin

Taxonomy. Delphinus peronii Lacépede, 1804,

“dans les environs du cap sud de la terre de Diémen, et par consequent vers le quarante-quatrime degree de latitude australe [= about 44° S, 141° E, south of Tasmania],” Indian Ocean.

This species is monotypic.

Distribution. Circumpolar in subantarctic waters, primarily between 30° S and 65° S, including the Great Australian Bight, Tasman Sea, and Chatham Is, but as far N as 25° S in the Malvinas Current, 23° S in the Benguela Current, and 12° S in the Humboldt Current.

Descriptive notes. Total length up to 300 cm; weight up to 116 kg. Neonates are thought to be ¢.100 cm long. Like its northern counterpart, the Northern Right-whale Dolphin (L. borealis), the Southern Right-whale Dolphin is torpedo-shaped but slightly more robust, and it has short, broad-based beak; shallow tailstock; small, slender flippers; and no dorsal fin. Skin has distinctive black and white coloring. Most offlanks and belly are white, and black streak runs dorsally from base offlukes along tail before dipping down into more of a cape over thoracic region and melon. Face and beak are white. Flippers are also white but may have dark trailing edge. Edges of flukes on dorsal side are dark gray. Some completely black individuals have occasionally been observed in New Zealand waters. There are 44-49 pairs of conical teeth in each jaw.

Habitat. Prefer deep, offshore waters of 1-20°C but may occur closer to shore along coasts off Chile and around New Zealand in water at least 200 m deep. The Southern Right-whale Dolphin appears to be restricted to southern temperate waters and is rarely observed south of the Antarctic Convergence. It may follow cool currents, such as the Humboldt Current, into lower subtropical zones. The Southern Right-whale Dolphin is most abundant off the Chilean coast (where there is major upwelling), between Patagonia and the Falkland Islands in the Falklands Current, and along the West-wind Drift in the Indian Ocean.

Food and Feeding. The Southern Right-whale Dolphin feeds on a variety of fish and cephalopod species. Lanternfish (Myctophidae) seem to be preferred. Individuals may dive more than 200 m while foraging.

Breeding. There is no specific information available for this species, but the Southern Right-whale Dolphin may hybridize occasionally with the Dusky Dolphin (Lagenorhynchus obscurus).

Activity patterns. The Southern Right-whale Dolphin travels at high speeds, up to 22 km/h, often leaping out of the water at low angles. When moving more slowly, an individual barely disturbs the water’s surface when breathing. Dives may last 6:5 minutes or more. The Southern Right-whale Dolphin does not appear particularly attracted to boats and only rarely bow-rides. Groups travel in V-shaped and “chorusline” formations, which may be tightly packed or more dispersed into subgroups.

Movements, Home range and Social organization. Groups of the Southern Right-whale Dolphin tend to contain a few hundred individuals. Average group size is 210 individuals off Chile, but groups of more than 1000 individuals have been reported. Southern Rightwhale Dolphins are often observed in mixed-species groups with the Dusky Dolphin, the Long-finned Pilot Whale (Globicephala macrorhynchus), the Short-beaked Common Dolphin (Delphinus delphis), and the Common Bottlenose Dolphin (Tursiops truncatus). There is some evidence for an inshore and northward migration of Southern Right-whale Dolphins during spring and summer off western South America and southern Africa. Nevertheless, some populations (e.g. off Namibia) appear to be year-round residents.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The IUCN Red List. There are currently no available estimates of abundance or population trends for the Southern Right-whale Dolphin. There are also no quantifications of mortality related to incidental catch, so threat status cannot be accurately assessed. Southern Right-whale Dolphins are caught purposefully on occasion for use as bait in crab fisheries and human consumption off Peru and Chile. They have been caught incidentally in the Chilean gillnet fishery for swordfish (Xiphius gladius) since it began in the early 1980s and in driftnets along the Peruvian coast. Planned future expansions of driftnet fisheries off southern Africa could become a problem for populations of Southern Right-whale Dolphin and should be monitored closely.

Bibliography. Hammond et al. (2008s), Jefferson, Newcomer et al. (1994), Jefferson, Webber & Pitman (2008), Lipsky (2009), Rose & Payne (1991), Visser et al. (2004), Yazdi (2002).