Phocoena spinipinnis (Burmeister, 1865)

English: Burmeister porpoise
German: Burmeister-Schweinswal
Spanish: Marsopa espinosa
French: Marsouin de Burmeister

Family Phocoenidae

Phocoena spinipinnis © Wurtz-Artescienza (see links)

1. Description

The body is robust with a small, blunt head and relatively large flippers. The dorsal fin is set behind the midline, triangular in shape and canted backward in an unusual fashion for a cetacean. The Spanish name for this porpoise "marsopa espinosa" meaning "spiny porpoise" refers to the series of tubercles present on the leading edge of the low dorsal fin. Colouration varies from dark to brownish grey on the back and sides, and a light grey on the ventral region. A dark patch often surrounds the eye. A dark grey stripe runs from the chin to the base of the flipper. A pair of stripes is also present on the abdominal region. Maximum reported length is 200 cm, and maximum weight 105 kg (Reyes, 2009), however of 402 Burmeister's porpoises examined in Peru the largest female measured 183cm and the largest male 182cm. The heaviest specimen weighed 79kg (Reyes and Van Waerebeek, 1995).

2. Distribution

P. spinipinnis ranges on the west coast of South America from Paita (05°11'S), Peru, south to Valdivia (39°46'S), Chile; on the east coast of South America from Santa Catarina (28°48'S), Brazil, south to Chubut (42°25'S), Argentina; and in coastal waters around Tierra del Fuego (Rice, 1998).

Distribution of Phocoena spinipinnis: temperate and subantarctic coastal waters around
South America (Hammond et al. 2008; © IUCN; enlarge map).

Whether Burmeister's porpoise has a continuous distribution throughout its range is unclear. There are numerous gaps in the known distribution along both Atlantic and Pacific coasts, but it was thought that many or most of these simply reflect a lack of survey effort in the areas concerned (Brownell and Clapham, 1999). Rosa et al. (2005), however, assessed the genetic differentiation among Burmeister's porpoises from different localities in Peruvian, Chilean, and Argentine waters. Clustering analyses indicate a major population differentiation along the South American Pacific coast, separating Peruvian from both Chilean and Argentine individuals, which has implications for conservation strategies.

3. Population size

There are no quantitative data on abundance (Carwardine,1995; Hammond et al. 2008; Reyes 2009). Burmeister's porpoise is very difficult to detect in any but calm conditions, a fact that may explain the discrepancy between the assumed abundance of this animal in coastal waters on the one hand and the relative rarity of field observations on the other. The animal's respiratory and diving behaviour does not lend itself to easy observation: swimming is highly unobtrusive, surfacing is quiescent, and relatively prolonged dives of 1-3 min are common (Brownell and Clapham, 1999).

4. Biology and Behaviour

Habitat: This is essentially a coastal species, which sometimes frequents rivers and estuaries and, off Tierra del Fuego, is occasionally observed inside the kelp line. Its habitat preferences seem to closely resemble those of the harbour porpoise, which is typically found shoreward of the 60m isobath, but occasionally they have been recorded offshore in up to 1000 m of water (Brownell and Clapham, 1999 and refs. therein). Although the species prefers close distance to shores of 100 - 1000 m and water depths of 5 - 25 m, there have been records from more offshore waters, 50 km from the coast of Argentina (Reyes, 2002, 2009).

Burmeister's porpoise is found associated with a broad range of water temperatures. At the southern limit of its distribution near Cape Horn and Tierra del Fuego, water temperatures range from 3°C in June to about 9°C in the summer months. To the north, the species appears to be associated with temperate waters in the two major northward flowing currents of South America, the Humboldt and Falklands Currents. The highest recorded temperature associated with a Burmeister's sighting was 19.5°C in Golfo San José, Argentina (Brownell and Clapham, 1999 and refs. therein).

Behaviour: A limited number of observations indicate that it is a very shy animal. Some records suggest that small groups scatter when frightened, or approached by a boat, and regroup later. (Carwardine, 1995). There are no reports of porpoising or bow-riding (Reyes, 2009). Behaviour is inconspicuous; they breathe with little surface disturbance (Jefferson et al. 1993).

Schooling: Very little is known about the natural history of this species. Most sightings are of less 2-8 individuals, but aggregations of up to 150 have been reported in waters approx. 30 m deep, presumably associated with foraging behaviour (Van Waerebeek et al. 2002; Reyes, 2009).

Food: Feeding is on demersal and pelagic fish, such as anchovies (Engraulis spp.), hake (Merluccius gayi), silverside (Odontesthes regia), sardine (Sardinops sagax), jack mackerel (Trachurus murphyi) as well as squid (Reyes and Van Waerebeek, 1995; Reyes, 2002; Garcia-Godos et al. 2007). The stomachs of some Chilean animals also contained small snails, crustaceans and mollusc egg capsules (Brownell and Clapham, 1999 and refs. therein).

Reproduction: There appears to be a protracted summer birth peak; most births in Peru apparently occur in summer to autumn. Gestation lasts 11-12 months (Reyes and Van Waerebeek, 1995; Reyes, 2009).

5. Migration

There is no evidence of seasonality in occurrence either off Peru or Chile and both sightings and by-catches (Peru) are made in all seasons (Van Waerebeek et al., 2002). A year-round population of Burmeister's porpoise appears to exist in the Beagle Channel, suggesting site-fidelity; sightings have been made in every month except August and September. Data on seasonal movements are sparse and come largely from entanglements and incidental sightings. At Golfo San José, Argentina, P. spinipinnis is observed almost exclusively in spring and summer. This suggests that seasonal movement (either north-south or inshore-offshore) does occur, although whether this is correlated with water temperature or abundance of prey is unknown. Seasonal porpoise movements inferred from capture rates of the "corvina" fishery off Valdivia, Chile, with animals caught inshore (up to 18.5 km from the coast) in summer, and offshore (18-37 km) in winter, are biased by fishing methods: fishermen move their nets offshore in winter. Although it is unclear whether this by-catch truly reflects movements by the porpoises, it is possible that Burmeister's porpoises migrate offshore to match seasonal movements of potential prey, sardines (Brownell and Clapham, 1999 and refs. therein). Movements of porpoises following sporadic cold-water intrusions associated with the Subtropical Convergence may account for sightings as far north as Uruguay and Brazil (Reyes, 2009).

6. Threats

Direct catch: The most extensive known takes occur in Peruvian waters, where Burmeister's porpoise is caught primarily in net fisheries, and where it has been used extensively for human consumption. Mortality in Peru was recently estimated as >450 per year and the high mortality is cause for considerable concern (Van Waerebeek and Reyes, 1994; Van Waerebeek et al. 1997). Reyes (2002) states that annual captures in Peru may account for up to 2,000 animals, but current numbers are unknown (Reyes 2009). At least some gillnets are set with the direct intent to capture porpoises (Van Waerebeek et al., 2002). It is widely suspected that Burmeister's porpoises were shot or harpooned for use as crab bait in southern Chile, although this has been reduced due to modified fishery operations (Reyes, 2009). However, because quantitative data are lacking, the current extent of this problem is unknown.

Incidental catch: By-catch occurs in various areas with-in the species' range, including Peru, Chile, Argentina, Uruguay and Brazil. Coastal or shark gill net fisheries are responsible for mortality in Burmeister's porpoise in Argentina (>12 per year), Tierra del Fuego, and, to a lesser extent, Uruguay. Takes are poorly documented in all areas (Brownell and Clapham, 1999 and refs. therein).

Between 1991 and 1998, observers stationed at the port of San Juan in southern Peru observed the landings of 214 Burmeister's porpoises. Most of these animals were captured in 1992-1994, when the fishers were mainly using surface-drift gillnets to target a pelagic schooling fish called cojinova (Seriolella violacea). Capture rates were much lower in 1995-1998, when fishers were mostly using fixed demersal gillnets and shellfish diving, due apparently to a lack of surface-schooling cojinova in the vicinity (Majluf et al. 2002). This clearly shows how alterations in gear type can reduce cetacean mortality.

More recently, South of Santa Cruz and in Tierra del Fuego,Argentina, the gill net fishery targeted at Patagonian blenny Eleginops maclovinus and silverside (Atherinidae) was made responsible for incidental porpoise mortality (Crespo et al. 2007).

Pollution: There has been only one study of pollutants in this species on eight animals caught in gill nets off northern Argentina. Organochlorine levels in all animals were low, a finding which is consistent with the relatively low degree of pollution known from local waters (Brownell and Clapham, 1999 and refs. therein).

7. Remarks

Range states (Hammond et al. 2008) :
Argentina; Brazil; Chile; Peru; Uruguay

Phocoena spinipinnis is considered as "Data Deficient" by the IUCN (Hammond et al. 2008). The species is included in Appendices II of CMS and CITES.

Jefferson and Curry (1994) summarise that existing information is insufficient to evaluate the effects of gillnets on porpoise populations, but where this is possible, impacts often prove to be severe. Gillnets represent the single most important threat to porpoises as a group. Better documentation of catches and new approaches to dealing with porpoise/gillnet interaction problems are clearly needed in order to enable an assessment of the effects and suggest mitigation measures in the case of Burmeister's porpoise. For conclusions and recommendations for small cetaceans off South America: please see Hucke-Gaete (2000).

8. Sources

· Brownell RL, Clapham PJ (1999) Burmeister's porpoise - Phocoena spinipinnis Burmeister, 1865. In: Handbook of Marine Mammals (Ridgway SH, Harrison SR, eds.) Vol. 6: The second book of dolphins and porpoises, pp. 393-410.
· Carwardine M (1995) Whales, Dolphins and Porpoises. Dorling Kindersley, London, UK, 257 pp.
· Crespo EA, Dans SL, Koen Alonso M, Pedraza SN (2007) Interactions between marine mammals and fisheries. In: "The Argentine Sea and its fisheries resources. Vol. 5. The marine Ecosystem" pp. 151-169
· García-Godos I, Van Waerebeek K, Reyes JC, Alfaro-Shigueto J, Arias-Schreiber M (2007). Prey occurrence in the stomach contents of four small cetacean species in Peru. The Latin American Journal of Aquatic Mammals 6(2).
· Hammond PS, Bearzi G, Bjørge A, Forney K, Karczmarski L, Kasuya T, Perrin WF, Scott MD, Wang JY, Wells RS, Wilson B (2008). Phocoena spinipinnis. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>.
· Hucke-Gaete R ed. (2000) Review on the conservation status of small cetaceans in southern South America. UNEP/CMS Secretariat, Bonn, Germany, 24 pp.
· Jefferson TA, Leatherwood S, Webber MA (1993) FAO Species identification guide. Marine mammals of the world. UNEP/FAO, Rome, 320 pp.
· Jefferson TA, Curry BE (1994) A global review of porpoise (Cetacea: Phocoenidae) mortality in gillnets. Biol Conserv 67: 167-183.
· Majluf P, Babcock EA, Riveros JC, Schreiber MA, Alderete W (2002) Catch and Bycatch of Sea Birds and Marine Mammals in the Small-Scale Fishery of Punta San Juan, Peru. Conserv Biol 16: 1333-1343.
· Reyes JC, Van Waerebeek K (1995) Aspects of the Biology of Burmeister's porpoise from Peru. Reports of the International Whaling Commission (Special Issue 16): 349-364.
· Reyes JC (2002) Burmeister's porpoise. In: Encyclopedia of marine mammals (Perrin WF, Würsig B, Thewissen JGM, eds.) Academic Press, San Diego, pp. 177-179.
· Reyes JC (2009) Burmeister's porpoise - Phocoena spinipinnis. In: Encyclopedia of marine mammals, 2nd Ed. (Perrin WF, Würsig B, Thewissen JGM, eds.) Academic Press, Amsterdam, pp. 163-167.
· Rice DW (1998) Marine mammals of the world: systematics and distribution. Society for Marine Mammalogy, Special Publication Number 4 (Wartzok D, ed.), Lawrence, KS. USA.
· Rosa S, Milinkovitch M, Van Waerebeek K, Berck J, Oporto J, Alfaro-Sigueto J, Van Bressem M, Goodall N, Cassens I (2005) Population structure of nuclear and mitochondrial DNA variation among South American Burmeister's porpoises (Phocoena spinipinnis). Cons Genet 6: 431-443.
· Van Waerebeek, K. and Reyes, J.C. 1994. Post-ban small cetacean takes off Peru: a review. Reports of the International Whaling Commission (Special Issue 15): 503-520.
· Van Waerebeek K, Van Bressem M F, Felix F, Alfaro Shigueto J, Garcia Godos A, Chavez Lisambart L, Onton K, Montes D, Bello R (1997) Mortality of dolphins and porpoises in coastal fisheries off Peru and southern Ecuador in 1994. Biol Cons 81: 43-49.
· Van Waerebeek K, Santillán L, Reyes JC (2002) An unusually large aggregation of Burmeister's porpoise Phocoena spninipinnis off Peru, with a review of sightings from the eastern South Pacific. Noticiario Mensual 350: 12-17

© Boris Culik (2010) Odontocetes. The toothed whales: "Phocoena spinipinnis". UNEP/CMS Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.