Vaquita – Last Chance for the Desert Porpoise

Vaquita Porpoise – Phocoena sinus

Estimated Population – 200 animals.

Background

The vaquita is one of six species of porpoise. The term ‘porpoise’ is derived from the Latin porcus for ‘pig’ and piscus for ‘fish’. Porpoises are quite distinct from other species of cetacean (whales, dolphins and porpoises). They are generally found close to the coast, they are smaller in size, have smaller flippers, no prominent beak and their teeth are laterally compressed to form a cutting edge.
The vaquita (Phocoena sinus) is a rare species of porpoise endemic to the northern extreme of the Gulf of California (Sea of Cortez), Mexico. It is the most critically endangered of all cetaceans, and also has the most limited distribution. Indeed, the Latin name sinus means ‘pocket’ or ‘bay’, referring to its restricted range.
Vaquita, meaning ‘little cow’ in Spanish, was only recognized in 1958 on the basis of a few skulls. It wasn’t until 1985 when fresh specimens were found and sightings of live animals made, that the vaquita was fully described.

Evolution:

Although geographically closer to the harbor porpoise off the coast of central California some 1,500miles/2,500km away, the vaquita is more closely related to a Southern Hemisphere species of porpoise. It’s closest cousin, the Burmeister’s porpoise occurs some 3,000 miles/5,000km away in Peru, and further south. Presumably, the vaquita evolved from an ancestral population that moved northward into the Gulf of California around one million years ago during the Pleistocene era.

Physical description:

The vaquita is the smallest of all cetaceans. The current known maximum length is 4’11”/1.5 m, and the weight about 99-110 lp/45-50kg. Females are larger than males, as is the case with most species of the porpoise family. The flippers are proportionately larger than in other phocoenids and the dorsal fin is taller and more falcate.
Although it shares the typical stocky body shape of all porpoises with a girth up to 68% of its body length and a blunt beakless head, the vaquita’s appearance is quite distinct from the other five porpoise species.
The vaquita has an even, dark gray tone on the back that morphs into a lighter gray on the sides ending in a whitish belly. However, by far its most distinguishing feature is its face. The vaquita sports a black ring around each eye, a stripe from chin to flipper and a definitive black lipped-smile.

Ecology and behavior:

Very little is known about the biology of the vaquita. As is usually the case with porpoises, they occur in small groups, most often of two, but groups of 8-10 have been sighted. There are relatively few records of the vaquita in the wild; they are inconspicuous and illusive, compounded by a strong aversion to boats. Vaquita do not ride the bow waves of boats, nor are they prone to aerial activity. Vaquita rise to breath with a slow, forward rolling movement that barely disturbs the sea surface before disappearing quickly, often for long periods. It has an indistinct blow, but makes a loud, sharp, puffing sound reminiscent of the harbor porpoise.
Females reach maturity sometime between 3 and 6 year of age, and males appear to be similar. Females give birth perhaps once every two years, with most calves being born in spring after a 10-11 month gestation period. The maximum known lifespan is 21 years.

Why are they disappearing?

The main threat to the vaquita is incidental catches in fishing gear, especially gillnets set for shrimp. The majority of shrimp is destined for the US market where it is now that nations most popular seafood choice. The estimated mortality from gillnet fishing is at least 39 (an maybe as many as 84) vaquitas per year, which is certainly unsustainable. 50 animals is the estimated minimum number of vaquita needed to maintain a reproductively fit population. Any lower than this means inbreeding would occur.

Vaquita aren’t the intended target of any fishery, they, as was also the case with the baiji in China, are merely the bycatch of local fishers trying to earn a living and feed their families. For the fishers of El Golfo de Santa Clara, San Felipe and Puerto Penasco, the Vaquita is collateral damage.
Conservation of the species has being attempted through the creation of a biosphere reserve and vaquita refuge, as well as the establishment of an international committee (CIRVA) convened by the Mexican government to recommend protection measures. However, implementation has been slow and the effectiveness of these measures is very much in doubt. Despite all this, the habitat appears relatively healthy and a glimmer of hope still remains for the vaquita.

Bycatch is a problem for cetaceans everywhere. An estimated 300,000 cetaceans are drowned every year in fishing gear set across the oceans, seas and rivers of the world. This equates to one cetacean death every two minutes as a direct result of our demand for seafood.