Vaquita Porpoise – Phocoena sinus
Class – Mammalia
Order - Cetacea
Suborder - Odontoceti
Family - Phocoenidae
Genus - Phocoena
Species - Phocoena sinus
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.
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.
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.
The few stomachs that have been examined indicate the vaquita preys on a wide range of demersal and benthic fishes, squids and crustaceans.
The vaquita is endemic to the relatively murky, shallow waters of the northern Gulf of California, near the estuary of the Colorado River. Most sightings have been in water less than 130ft/40m depth and within about 25 miles/40km of shore.
The vaquita is listed as Critically Endangered by the IUCN Red List authority, and has received a great deal of attention within the IUCN Cetacean Specialist Group and the International Whaling Commission’s Small Cetacean Subcommittee. There is widespread acceptance within the marine mammal community of the extremely serious situation that the species is in, and for many years it has been considered the second-most endangered cetacean species, after the baiji (Lipotes vexillifer) of China’s Yangtze River.
With the recent discovery that the baiji is functionally extinct, the vaquita is now recognized as the most-endangered cetacean species in the world. Based on abundance estimated in 1997 (567) and information on life history and recent mortality rates, there are estimated to be only about 150 vaquitas remaining. (They are thought to have numbered in the low thousands at the time of discovery). Based on expected levels of decline, this means there is a window of about two years in which to implement solutions to save the species. After that, it will likely be too late.
The main threat to the vaquita is incidental catches in fishing gear, especially gillnets set for shrimp and fish. The 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.
The vaquita is also threatened by the dwindling flow of fresh water from the Colorado River into the gulf, depleted by western U.S. cities for drinking water. The water that does make it to the gulf carries high levels of agricultural runoff that may alter the gulf's chemistry.
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.
What is being done to save the vaquita from extinction?
The government of Mexico is currently developing a plan to remove entangling nets from the vaquita’s range, compensate fishermen with alternative livelihood options, and enforce net removal. The impact of these activities on local fishing communities will be significant and because of this, a critical part of the conservation plan is to monitor the vaquita population over time.
Acoustic methods have been identified as the best monitoring strategy because vaquita are difficult to detect visually (group size is small, they avoid ships, they spend little time at the surface). Unfortunately, currently used acoustic methods are not adequate to monitor a species as rare as vaquita. Mexico’s Instituto Nacional de Ecología (INE) has therefore requested collaborative support from the international scientific community, NOAA Fisheries included, to develop new autonomous acoustic monitoring methods.
In response to this invitation, US and Mexican scientists together with expert acousticians from Great Britain, the United States and Japan planned and conducted a research cruise in the fall of 2008.
The objective of the cruise was to develop, test, and calibrate an acoustic monitoring system that: can cover a sufficient part of vaquita range to reliably detect trends in abundance with the objective of being able to detect a 4%/year increase as “positive growth” within a 10 year period (this is a 50% population increase if maximum growth rates occur).
What can you do?
What is currently needed is public support. The plight of the vaquita is not well known outside the marine mammal community, or in the surrounding geographic areas of northern Mexico and the southwestern United States. Follow updates in the coming months on the effort to save the vaquita on vaquita.tv
Donate online to our site - Vaquita - The Search for the Desert Porpoise. Funds will be used to maintain this bilingual website and support conversation and collaborative conservation efforts between groups in Mexico and the United States.
At a grass-roots level, the most important thing you can do is to be aware of where the seafood you consume is coming from, and how it is caught. Fishing is still the greatest threat to cetaceans worldwide, and fisheries kill hundreds of thousands of marine mammals every year. A number of non-profit organizations have published guidelines for making sustainable seafood choices. Also, it is important to let your government representatives know that a healthy ocean is important to you.
- Articles -How now, little cow? http://findarticles.com/p/articles/mi_m1134/is_6_116/ai_n27283540Vaquita Porpoise, and a Way of Life, Face Extinction http://www.nytimes.com/2007/02/13/world/americas/13dolphin.htmlPapers –Saving the Vaquita: Immediate Action, Not More Data. Jaramillo-Legorreta et al., 2007. http://www.vaquita.org/PDF%20Files/Jaramillo_et_al_2007_Conservation_Biology%5B1%5D.pdf
- Conservation of the Vaquita (Phocoena sinus). Rojas-Bracho et al., 2006. http://www.vaquita.org/PDF%20Files/Rojas Bracho%20et%20al.,%202006%20(MMMR).pdf
- Vaquita Bycatch in Mexico's Artisanal Fisheries: Driving a Small Population to Extinction. D'Agrosa et al., 2000. http://www.vaquita.org/PDF%20Files/D%27Agrosa%20et%20al.,%202000%20(CB).pdf
Related websites -
- www.iucn.org www.iucnredlist.org IUCN, the International Union for Conservation of Nature, helps the world find pragmatic solutions to our most pressing environment and development challenges. It supports scientific research, manages field projects all over the world and brings governments, non-government organizations, United Nations agencies, companies and local communities together to develop and implement policy, laws and best practice
- www.iwcoffice.org The International Whaling Commission (IWC) was set up under the International Convention for the Regulation of Whaling in Washington DC on 2 December 1946. It is most famous for implementing an international moratorium on all commercial whaling after whale populations were decimated by decades of unsustainable hunting.
References and acknowledgments:
- Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A. & Taylor, B.L. (2007). Phocoena sinus. 2007 IUCN Red List of Threatened Species. IUCN 2007.Jefferson, T. Webber, M. Pitman, R. (2008).
- Marine Mammals of the World - A Comprehensive Guide to their Identification. Elsevier, UK.Reeves, R. Stewart, B. Clapham, P. Powell, J. (2002). Guide to Marine Mammals of the World. Knopf Inc. NY.