Gulf of california harbor porpoise - Phocoena sinus

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The vaquita is among the smallest of all marine cetaceans. Compared to other phocoenids, it has a taller, more falcate dorsal fin and larger flippers. Like all porpoises, it is stocky, with a blunt beakless head. Vaquitas have black to dark gray lip patches and eye rings; otherwise the body is light brownish gray. Calves tend to be somewhat darker than adults.

In the small number of specimens examined to date, there have been 16-22 pairs of teeth in the upper jaw and 17-20 pairs in the lower jaw. Known maximum length is 1.5 m (females) and 1.45 m (males), but very few specimens have been examined.

When seen at a distance, the tall dorsal fin of the vaquita must be distinguished from those of bottlenose and long-beaked common dolphins, both of which are common in the vaquita’s range. However, the small group size and unique body shape will generally allow the vaquita to be distinguished.

The restricted distribution of the vaquita appears to be defined by relatively murky coastal waters in the northern quarter of the Gulf of California, although there are some suggestions that the range may extend further south in the Gulf as well.

Very little is known of the biology of the vaquita. As is generally true for porpoises, they occur in small groups, most often of about two, although groups of up to 8-10 have been sighted. They are relatively inconspicuous in their behavior, and are not known to ride bow waves. Aerial behavior is rare.

Most calving apparently occurs in the spring.

Only 34 stomachs have been examined, and the contents indicated opportunistic feeding on a wide array of demersal and benthic fishes, squids, and crustaceans.

The vaquita, along with the baiji, is one of the two most endangered species of cetaceans in the world. There are a number of potential identified threats, including habitat changes associated with reduction in freshwater flow to the Gulf, inbreeding depression, and environmental contamination. By far, however, main threat is incidental catches in fisheries, especially various bottom-set gillnets. Estimated annual mortality from gillnet fishing is 39-84 vaquitas per year, which is thought to be unsustainable. Conservation of the vaquita is being achieved through the creation of a biosphere reserve in the upper Gulf of California, and the establishment of an international committee to recommend protection measures. Currently, the conservation statuses of the vaquita are ‘Critically Endangered’ (IUCN) and ‘Endangered’ (ESA).

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Jaramillo-Legorreta, A.M., L. Rojas-Bracho and T. Gerrodette. 1999. A new abundance estimate for vaquitas first step for recovery. Marine Mammal Science 15:957-973.

Rojas-Bracho, L. and B.L. Taylor. 1999. Risk factors affecting the vaquita (Phocoena sinus). Marine Mammal Science 15:974-989.

Rojas-Bracho, L. and A. Arammillo-Legorreta. 2002. Vaquita Phocoena sinus. pp. 1277-1280 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

Silber, G.K. and K. S. Norris. 1991. Geographic and seasonal distribution of the vaquita, Phocoena sinus. Anales de la Instituto Biologia, Universidad Nacional Autonoma de Mexico, Serie Zoologie 62:263-268.

Vidal, O. 1995. Population biology and incidental mortality of the vaquita, Phocoena sinus. Reports of the International Whaling Commission Special Issue 16:247-272.

Vidal, O., R.L. Brownell, Jr. and L.T. Findlay. 1999. Vaquita Phocoena sinus Norris and McFarland, 1958. pp. 357-378 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 6: The second book of dolphins and the porpoises. Academic Press.