Phocoena spinipinnis Burmeister 1865

4.

Burmeister’s Porpoise

Phocoena spinipinnis

French: Marsouin de Burmeister / German: Burmeister-Schweinswal / Spanish: Marsopa espinosa

Other common names: Black Porpoise

Taxonomy. Phocaena spinipinnis Burmeister, 1865,

Argentina, Buenos Aires, “captured in the mouth of the River Plata.”

This species is monotypic.

Distribution. Near-shore waters of South America, from N Peru (5° S) S to Cape Horn and up the Atlantic coast to S Brazil (28° 50” S). Records from Uruguay and Brazil may be associated with N extrusions ofcold water.

Descriptive notes. Total length 150-200 cm; weight 50-105 kg. Burmeister’s Porpoises regularly reach lengths of up to 185 cm (although individuals up to 200 cm long have been reported from Uruguay), and males are slightly larger than females. Body shapeis generally typical of that of phocoenids, with a moderately robust form. Head has a very short, poorly defined beak. Flippers are broad-based with rounded tips, and flukes are typical of other small cetaceans. Dorsal fin is unique; it rises at a very shallow angle from the posterior portion of the back and is narrow, with a convex trailing edge and a slightly concave or straight leading edge. There are several small tubercles along leading edge of dorsal fin, and sometimes on flippers, which give Burmeister’s Porpoise its scientific name. Coloration is generally uniform dark gray, with a slightly paler belly. There are subtle stripes, streaks, and patches on the head, including dark eye and lip patches, a dark chin-to-flipper stripe, and pale streaks on chin and undersides. Flipper stripes are asymmetrical, being narrower and extending farther forward on the right side. Tooth counts generally are 10-23 in each half of each jaw.

Habitat. Shallow coastal waters from very near the shoreline up to 50 km offshore. Burmeister’s Porpoises occur in some open-ocean waters but also in enclosed bays, channels, and fjords, and they have even been seen upstream in some rivers. They inhabit cooler waters, and water temperature may limit their northern distribution.

Food and Feeding. Burmeister’s Porpoises feed on a variety of pelagic and demersal fish and invertebrate species, including anchovies (Engraulis and Anchoa), hake (Merluccius), sardines (Sardinops or Sciaena), silversides (Odontesthes), sculpin (Normanichthys), squid (such as Loligo), and shrimps. In the central coast of Peru, fish generally make up the majority of the prey items (98%).

Breeding. Life history of Burmeister’s Porpoise has not been well studied, but sexual maturity appears to occur at lengths of ¢.160 cm in males and c.155 cm in females. Gestation lasts ¢.11-12 months. There are apparently protracted summer birthing peaks in most populations, and in Peru (where they have been best studied), most births occur in late summerto early autumn.

Activity patterns. Very little is known about behavior and activities of Burmeister’s Porpoises, which have not been the subject of many ecological studies. Like other porpoises, they appear to be shy and inconspicuous, often avoiding vessels. They do not bow ride, and aerial behavior appears to be rather rare.

Movements, Home range and Social organization. They live in small groups that generally number up to six individuals. On occasion, aggregations of up to 70 individuals have been reported, but these are presumably opportunistic. Although little is known for certain,it is expected that social bonds are largely short term and transitory. Essentially nothing is known about individual movements or ranging patterns of Burmeister’s Porpoises because no tagging or photo-identification studies have been conducted.

Status and Conservation. CITES Appendix II. Classified as Data Deficient on The IUCN Red List. Although very little is known about stock structure in Burmeister’s Porpoises, there appear to be separate populations in Peruvian and Chilean-Argentine waters. Nevertheless, it is not clear if there is a distributional gap separating them. Burmeister’s Porpoises have been hunted with harpoons and nets in Peru and Chile, and the meat is mostly used for human consumption (at least in Peru) and shark and crab bait. These direct kills have been supplemented with incidental kills in gillnets. In Peru, up to 2000 porpoises/year may be killed. Like all members of the family, Burmeister’s Porpoises are vulnerable to gillnet entanglement, and these kills are thought to threaten some populations. Other potential threats include mortality in other fisheries, environmental contamination, and habitat alteration. Essentially nothing is known about abundance or population trends of Burmeister’s Porpoises, but the Peruvian population appears threatened by the high kill rates.

Bibliography. Beilis et al. (2000), Brownell & Clapham (1999b), Corcuera et al. (1995), Garcia-Godos et al. (2007), Goodall, Norris et al. (1995), Goodall, Wirsig et al. (1995), Heinrich et al. (2008), Molina-Schiller et al. (2005), Reyes (2009), Reyes & Van Waerebeek (1995), Rosa et al. (2005), Van Bressem et al. (2007), Van Waerebeek & Reyes (1990, 1994), Van Waerebeek et al. (2002).