Endemic to upper quarter of Gulf of California, extent of occurrence (EOO) >2,000 km², area of occupancy (AOO) (core area) approx. 2,000 km².
The range of Phocoena sinus is extremely restricted. This species of porpoise is found only in the northern end of the Gulf of California. Phocoena sinus (commonly known as the vaquita) are found only in shallow water, close to shore.
Biogeographic Regions: pacific ocean (Native )
- UNESCO-IOC Register of Marine Organisms http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1318
Mexico (Gulf of California)
Adult vaquitas are typically 1.2 to 1.5m in length with females being slightly larger than males. At birth their average length is 0.6-0.7m. Juveniles also have white spots on their dorsal fins.
Phocoena sinus has between 34-40 teeth which are unicuspid, or "acorn like" (Silber, 1990) and a blunted rostral profile. P. sinus are physically similar to the Harbor Porpoise (/Phocoena phocoena/) in many ways with an exception being that the vaquita is more slender. This has been explained in terms of their warmer habitat--the slender body increases surface area/volume ratio thus increasing heat dissipation in a warm environment. This explanation has also been used to explain the occurrence of larger appendages within this species (Hohn et al., 1996).
Range mass: 30 to 55 kg.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Habitat and Ecology
An interesting feature of the vaquita is that it is the only species of porpoise that is found in such warm waters. Most phocoenids are restricted to water cooler than 20 degrees Celsius, vaquitas are unique in their ability to tolerate large annual fluctuations in temperature (Hohn, et al, 1996). The Gulf of California may experience temperature ranges from 14 degrees C in January to 36 degrees C in August. This may have an effect on the reproductive seasonality of this species.
Aquatic Biomes: coastal
- UNESCO-IOC Register of Marine Organisms http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1318
Depth range (m): 0 - 0
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Vaquitas feed on teleost fishes and squid, which are found near the surface of the water. In several individuals the remains of Guld croakers were found.
Animal Foods: fish; mollusks
Primary Diet: carnivore (Piscivore )
Life History and Behavior
Vaquitas are usually solitary. This would indicate a social system in which sperm competition is extremely important (Hohn et al., 1996). Within such systems, males attempt to maximize their fitness not by monopolizing access to females, but rather by mating with as many females as possible. As would be expected in multi-male breeding systems, male vaquitas have relatively large testes size in comparison to their body size.
Mating System: polygynous
Sexual maturity is believed to be reached between the ages of three and six years. Body mass may help to distinguish mature from immature specimens for both males and females (Hohn et al., 1996). Vaquitas have highly seasonal reproduction. During the spring there is a complete lack of larger calves. The mating period is from mid-April to May, with a gestation period of roughly 10.6 months. Births occur at the beginning of the following March. P. sinus have non-annual ovulation, thus they do not produce calves each year (Hohn et al., 1996). Females have one calf per pregnancy and lactate for less than one year.
Breeding season: The mating period is from mid-April to May
Average number of offspring: 1.
Average gestation period: 10.6 months.
Range weaning age: 12 (high) months.
Average weaning age: 12 months.
Range age at sexual or reproductive maturity (female): 3 to 6 years.
Range age at sexual or reproductive maturity (male): 3 to 6 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
In 2012, Phocoena sinus was included among the world's 100 most threatened species, in a report by the IUCN Species Survival Commission and the Zoological Society of London.
- Fiona Harvey (September 10, 2012). "The expendables? World's 100 most endangered species listed". The Guardian. http://www.guardian.co.uk/environment/2012/sep/11/100-most-endangered-species-listed. Retrieved March 1, 2013.
- Jonathan E. M. Baillie & Ellen R. Butcher (2012). Priceless or Worthless? (PDF). Zoological Society of London. ISBN 978-0-900881-67-1. http://static.zsl.org/files/priceless-or-worthless-final-wq-2040-2050.pdf
IUCN Red List Assessment
Red List Category
Red List Criteria
The generation time for the vaquita is estimated as 10 years (Rojas-Bracho and Taylor 1999, Taylor and Rojas-Bracho 1999), therefore three generations is approximately 30 years.
Criterion A4d: Given what is known about fishing history in the northern Gulf of California and the vaquita?s vulnerability to entanglement in gillnets, it is reasonable to assume that the porpoise population has been declining since the 1940s when gillnet fisheries became widespread in the region. The best estimate of total population size is from 1997: 567 (95% CI: 177, 1,073) (Jaramillo-Legorreta et al. 1999). The estimated annual level of mortality in the early 1990s for one of the three main fishing communities, based on reports from onboard observers (Method 1) and those observer reports combined with information from interviews with fishermen (Method 2), was 84 (95% CI: 14, 155) (Method 1) or 39 (95% CI: 14, 93) (Method 2) (Rojas-Bracho and Taylor 1999, D?Agrosa et al. 2000). Using the 1997 abundance estimate, the range of bycatch estimates for a single community in the early 1990s, and plausible potential rates of population increase for phocoenids, Rojas-Bracho and Taylor (1999) estimated that the vaquita population was declining rapidly, possibly by as much as 15% per year. Using the lower of their plausible decline rates (0.05), the population size would be reduced by more than 80% over three generations (i.e., 30 years), including both the past and the future (Rojas-Bracho and Taylor 1999). The cause of the reduction (incidental mortality in fisheries) has not ceased and may even have increased over the last 10 years based on fishing effort (ca. 1,000 gillnet boats might operate in vaquita habitat each year; Rojas-Bracho et al. 2006).
Criterion C2a(ii): The mature and reproductively active component of the census population is estimated as 0.55 (Woodley and Read 1991), or 311 in 1997. Given the inferred decline in abundance due to fishery bycatch during the nine years since 1997 (possibly at a rate of 0.05 to 0.15/yr according to Taylor and Rojas-Bracho 1999), there are now plausibly far fewer than 250 mature individuals (criterion C). From available data on fishery activities (types and effort) and vaquita bycatch rate, a continuing decline in number of mature individuals is projected and inferred (C2). It is assumed that the species population is not divided into subpopulations and therefore 100% of mature individuals are in a single population (C2aii).
- 2007Critically Endangered
- 1996Critically Endangered
- 1994Endangered(Groombridge 1994)
- 1990Endangered(IUCN 1990)
- 1988Vulnerable(IUCN Conservation Monitoring Centre 1988)
- 1986Vulnerable(IUCN Conservation Monitoring Centre 1986)
Vaquita are listed as critically endangered. They are perhaps the most endangered of the cetaceans with only a few hundred remaining. Phocoena sinus are often caught in fishing nets which are set to catch other marine animals, most often shrimp. This species becomes entangled either in the shrimp nets or within gillnet fisheries for sharks. It is estimated that 25-30 individuals drown each year as a result. To further complicate the situation, relatively few individuals reach maturity because of the high mortality of young individuals (they are highly susceptible to being netted), and the remaining older individuals are approaching the upper limit of their lifespan so as to be contributing little to future reproduction (Hohn et al, 1996).
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: critically endangered
Date Listed: 01/09/1985
Lead Region: Foreign (Region 10)
Population location: entire
Listing status: E
For most current information and documents related to the conservation status and management of Phocoena sinus , see its USFWS Species Profile
There is no immediate means of estimating trend, so it is necessary to impute the direction and rate of population change by reference to a population model laden with assumptions.
Naturally rare (Taylor and Rojas-Bracho 1999) and very difficult to detect and count (cryptic) (Gerrodette et al. 1995). No population subdivision is known or suspected, i.e. no subpopulations, but also no fragmentation. Most recent estimate of total population size (1997 shipboard line transect survey): 567 (95% CI 177 to 1,073) (Jaramillo-Legorreta et al. 1999).
Given the difficulty of sampling the vaquita population, generation time and percent mature (i.e., capable of reproduction) can only be estimated crudely and by analogy with the life history and population biology of the better-studied harbour porpoise (Phocoena phocoena). Thus reasonable default values for porpoises (phocoenids) would be 10 years and 55%, respectively.
Ongoing decline inferred from available information on abundance and bycatch rate. Even an unrealistically optimistic scenario - high end of 95% CI for population size (1,073), lower of two estimates of annual bycatch mortality for a single fishing port (39 porpoises) - indicates likely decline (Rojas-Bracho and Taylor 1999).
An International Committee for the Recovery of the Vaquita (CIRVA) was established in 1997 and has developed recommendations including: immediate prohibition of large-mesh gillnets throughout the species' known range, followed in sequence by bans on medium- and small-mesh gillnets; exclusion of gillnets and trawls within an enlarged biosphere reserve; and improved enforcement of fishing regulations in the northern Gulf generally. Considerable attention has also been given to development of less harmful fishing methods, alternative income-generating activities for fishing communities, and community-based education and awareness (Rojas-Bracho et al. 2006).
On 29 December 2005 the Mexican Ministry of Environment declared a Vaquita Refuge that contains within its borders approximately 80% of all verified vaquita sighting positions. In the same decree, the State Governments of Sonora and Baja California were offered $(US)1 million to compensate affected fishermen. The results of this action cannot yet be evaluated.
It is listed on CITES Appendix I.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
P. sinus may interfere with human activity is in that it may inadvertantly become entangled in fishing nets set for shrimp, sharks, and totoabo causing a nuisance and possibly reducing catch during one net hauling.
Economic Importance for Humans: Positive
This species is not used directly by humans. It is interesting in the sense that it is a unique phocoenid morphologically and behaviorally. The fact that it is limited in its range and is extremely endangered should encourage study of the vaquita.
IUCN Red List Category
- IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species. http://www.marinespecies.org/aphia.php?p=sourcedetails&id=125373
The vaquita (Phocoena sinus) is a rare species of porpoise. It is endemic to the northern part of the Gulf of California. Estimates of the number of individuals alive range from 100  to 300. The word "vaquita" is Spanish for little cow. Since the baiji (Lipotes vexillifer) is believed to have gone extinct in 2006, the vaquita has taken on the title of the most endangered cetacean in the world.
Other names include cochito, Gulf of California harbor porpoise, Gulf of California porpoise, and gulf porpoise.
Physical description 
The vaquita are the smallest species of porpoise and are found only in the northern end of the Gulf of California. The vaquita has a classic porpoise shape. They are stocky and curve into a star shape when viewed from the side. The species is distinguishable by the dark rings surrounding their eyes, patches on their lips, and a line that extends from their dorsal fins to their mouth. Their back is a dark grey that fades to a white underside. As vaquitas mature, the shades of grey lighten . Individuals only reach a size of 1.2-1.5 m (4–5 ft) and a weight of 40–55 kg (90-120 lb) when fully mature. The flippers are proportionately larger than other porpoise's and the fin is taller and more falcate. The skull is smaller and the rostrum is shorter and broader than in other members of the genus. The females are discernible from the males due to their larger size.
The habitat of the vaquita is restricted to the northern area of the Gulf of California, or Sea of Cortez. Vaquitas live in shallow, murky lagoons along the shoreline. They rarely swim deeper than 30 meters and are known to survive in lagoons so shallow that their back protrudes above the surface. The vaquita is most often sighted in water 11 to 50 metres deep, 11 to 25 kilometres from the coast, over silt and clay bottoms. Vaquitas tend to choose habitats with turbid waters, due to the fact that they have high nutrient content. The high nutrient content is important because it attracts the small fish, squid, and crustaceans that Vaquitas feed on. They are able to withstand the significant temperature fluctuations characteristic of shallow, turbid waters and lagoons.
There are very few records of the vaquita in the wild. They appear to swim and feed in a leisurely manner, but they are elusive and will avoid boats of any kind. Vaquitas rise to breathe with a slow, forward-rolling movement that barely disturbs the surface of the water, and then disappear quickly, often for a long time. In order to explore their environment and communicate with each other, vaquitas use sonar and produce high-frequency clicks that are used in echolocation.
Like other Phocoena, the vaquita are usually seen by themselves. If they are seen together, it is usually in small groups, ranging from 1 - 3 individuals in size. Less often groups of around 8 to 10 have been observed, with the most ever seen at once being 40 individuals.
Vaquitas tend to forage near lagoons. All of the 17 fish species found in vaquita stomachs can be classified as demersal and or benthic species inhabiting relatively shallow water in the upper Gulf of California. It appears that the vaquitas are rather non-selective feeders on small fishes and squids in this area. Like other cetaceans, vaquitas may use echolocation to locate prey. It also is possible that vaquitas locate their prey by following the sounds given off by prey movement.
Vaquitas sexually mature at 1.3 meters, between 3 and 6 years old. They have seasonal reproduction, and usually have one calf in March. Their gestation period is between 10 and 11 months. The interbirth period, or elapsed time between offspring birth, is between 1 and 2 years. The maximum observed life span is 21 years.
Vaquita have never been hunted directly, but it is known that the vaquita population is declining. Estimates placed the vaquita population at 567 in 1997. With their population dropping as low as 150 individuals in 2007 and possibly even lower today, inbreeding depression has begun to affect the fitness of the species,further accelerating the population’s decline. The decline in the vaquita population is believed to be due to animals becoming trapped in gillnets intended for capturing the totoaba, another species endemic to the Gulf.
The vaquita is one of few marine mammal species and is considered the most endangered. The vaquita has been classified as one of the top 100 Evolutionary Distinct and Globally Endangered (EDGE) mammals in the world. The vaquita is an evolutionarily distinct animal and has no close relatives. These animals represent more, proportionally, of the tree of life than other species, meaning they are top priority for conservation campaigns. The EDGE of Existence Programme is a conservation effort that attempts to help conserve endangered animals that represent large portions of their evolutionary trees. The U.S. government has listed the vaquita as endangered under the Endangered Species Act (ESA). The vaquita is also listed by the International Union for the Conservation of Nature (IUCN) and the Convention on International Trade in the Endangered Species of Wild Fauna and Flora (CITES) in the most critical category at risk of extinction.
Because vaquitas are indigenous to the Gulf of California, Mexico is predominantly leading conservation efforts with the creation of the International Committee for the Recovery of the Vaquita (CIRVA), which has attempted to help prevent the accidental deaths of vaquita by outlawing the use of fishing nets within the vaquita’s habitat. CIRVA has worked together with the CITES, the ESA, and the Marine Mammal Protection Act (MMPA) to make a plan to nurse the vaquita population back to a point at which they can sustain themselves. CIRVA concluded in 2000 that between 39 and 84 individuals are killed each year by such gillnets. In order to try to prevent extinction, the Mexican government has created a nature reserve covering the upper part of the Gulf of California and the Colorado River delta. CIRVA recommends that this reserve be extended southwards to cover the full known area of the vaquita's range and that trawlers be completely banned from the reserve area.
On October 28, 2008, Canada, Mexico, and the United States launched the North American Conservation Action Plan (NACAP) for the vaquita., under the jurisdiction of the Commission for Environmental Cooperation (CEC), a NAFTA environmental organization. The NACAP is a strategy to support Mexico’s efforts to recover the vaquita.
Possible Threats 
- Other lesser-discussed culprits of human-based threats on the vaquita population include pollutants and habitat alterations. The habitat of the vaquita is small and the food supply in marine environments is largely dependent on water levels. The damming of the upper Colorado river has potentially decreased the food supply by decreasing water levels, indirectly effecting the vaquita population and ability to reproduce. In addition to reduced flow of freshwater from the Colorado River due to damming, the use of chlorinated pesticides and depression due to inbreeding may also have a detrimental effect. Despite the potential detrimental effects, it is important to note that most of the recovered bodies of the vaquitas show no signs of emaciation or environmental stressors, implying that the decline in the vaquita population is accredited almost solely to by-catch. However these additional hazards may pose a threat in the long-term. Even with a gillnet ban through The Refuge Area for the Protection of the Vaquita which contains 50% of the vaquita’s habitat, the population is still in decline which suggests a complete ban of gillnet use may be the only solution to saving the vaquita population.
Primary Impact 
- Removal of the vaquita will have a significant ecological impact on the Northern Gulf of California. The Gulf of California is considered a Large marine ecosystem (LME), due to its high species diversity and large habitat size. With such biodiversity in the region, it is important to consider the potentially harmful effects of slight drops in the vaquita population on seemingly unrelated species due to apparent competition.
- Sharks have been determined to be the only predators of vaquitas. Due to its limited number of predator species, the vaquita population is sensitive to small changes in predation from sharks. Although the vaquita accounts for only a small percentage of the diets of sharks in the region, extinction of the vaquita could potentially cause negative effects on shark population sizes. Extinction of the vaquita may also impact the vaquita prey populations in the Northern Gulf ecosystem. The disappearance of the vaquita could lead to potential over-population of their prey species such as benthic fishes, squid, and crustaceans.
- Conservation efforts for the vaquita are mainly focused on fishing restrictions to prevent vaquita bycatch. These fishing restrictions could prove beneficial for the fish in the upper gulf as well as the vaquita. As a result of increased restrictions on gillnet use, the populations of the targeted fish and shrimp species will receive protection from overfishing. Historically, numerous commercially fished species have experienced devastating impacts due to overfishing, and the vaquita conservation program may lessen the severity of such devastation in the future. Another solution to prevent vaquita bycatch might be to redesigning fishing nets. A redesigned net could be used to effectively catch fish but leave the vaquita untouched.
Secondary Impact of Declining Numbers 
- Though the major cause of vaquita porpoise mortality is bycatch in gillnets, numbers continue to dwindle and new factors will arise that will cause the population to further decline. One future problem that will arise with the current rate of population decline is reduced breeding rates. With less vaquita porpoise individuals in the habitat, there will eventually be significantly less contact between the different sexes and consequently less reproduction. With an even lower reproductive rate, the rate of population decline will increase. With lower contact levels between sexes, there may likely be reduced fitness due to inbreeding and less genetic variability in the gene pool, following the bottleneck effect.
- When inbreeding depression occurs, the population experiences reduced fitness because deleterious recessive genes can manifest the population. In small populations where genetic variability is low, individuals are more genetically similar. When the genomes of mating pairs are more similar, recessive traits appear more often in offspring. The more related two individuals are in the breeding pair, the more deleterious homozygous genes the offspring will likely have which can greatly lower fitness in the offspring  It is important to note that these secondary impacts of dwindling vaquita numbers are not necessarily a threat yet, but they will become problematic if the vaquita population continues to decline.
See also 
This article incorporates text from the ARKive fact-file "Vaquita" under the Creative Commons Attribution-ShareAlike 3.0 Unported License and the GFDL.
- Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A. & Taylor, B.L. 2008. “”Phocoena sinus. In: IUCN 2012. IUCN Red List of Threatened Species.”” Version 2012.2. [www.iucnredlist.org]. 2013.
- Whales, Dolphins and Porpoises, Carwardine, 1995, ISBN 0-7513-2781-6
- Aquarium Passport Book, Aquarium of the Pacific 2005
- "Vaquita (Phocoena sinus)". Encyclopedia of Endangered Species. Volume 1. Gale. 1 February 2009. Retrieved 2 November 2011.
- Turvey, S.T.; Pitman, R.L., Taylor, B.L., Barlow, J., Akamatsu, T., Barrett, L.A., Zhao, X., Reeves, R.R., Stewart, B.S., Wang, K., Wei, Z., Zhang, X., Pusser, L.T., Richlen, M., Brandon, J.R. and Wang, D. (2007). "First human-caused extinction of a cetacean species?". Biology Letters 3: 537–540. doi:10.1098/rsbl.2007.0292. PMC 2391192. PMID 17686754.
- Jaramillo-Legorreta, A.; Rojas-Bracho, L., Brownell Jr, R.L., Read, A.J., Reeves, R.R., Ralls, K. and Taylor, B.L. (2007). "Saving the vaquita: immediate action, not more data.". Conservation Biology 21 (6): 1653–1655.
- Barlow, Jay, Dr. “"Mammals."” EDGE of Existence. The Zoological Society of London, n.d. 2013.
- Jefferson, Thomas A., Marc A. Webber, and Robert L. Pitman. “”Marine Mammals of the World: A Comprehensive Guide to Their Identification.”” London: Academic, 2008.
- Examining the risk of inbreeding depression in a naturally rare cetacean, the Vaquita, Taylor and Rojas-Bracho, Marine Mammal Science Vol 15. Pages 1004-1028.
- "Vaquita (Phocoena sinus)". The Zoological Society of London. Retrieved 22 April 2013.
- "Gulf of California Harbor Porpoise / Vaquita / Cochito (Phocoena sinus)". NOAA Fisheries Office of Protected Resources. Retrieved 22 April 2013.
- "Project Summary". Commission for Environmental Cooperation. 2011. Retrieved 5 November 2011.
- Rojas-Bracho, Lorenzo, Reeves, Randall R., Jaramillo-Legorreta, Armando. Conservation of the vaquita Phocoena sinus. Mammal Rev., 2006,Volume 36, No. 3, 179–216.
- Gerrodette, T., B. L. Taylor, R. Swift, S. Rankin, A. M. Jaramillo-Legorreta, and L. Rojas-Bracho. A combined visual and acoustic estimate of 2008 abundance, and change in abundance since 1997, for the vaquita, Phocoena sinus., Marine Mammal Science, 2011
- Diaz-Uribe, J. Gabriel; Francisco Arreguín-Sánchezb, Diego Lercari-Bernierc, Víctor H. Cruz-Escalonab, Manuel J. Zetina-Rejónb, Pablo del-Monte-Lunab, Susana Martínez-Aguilara (10). "An integrated ecosystem trophic model for the North and Central Gulf of California: An alternative view for endemic species conservation". Ecological Modeling 230: 73–91. Retrieved 21 April 2013.
- Elton, Catherine (November/December 2011). "Safety Net". Audubon 113 (6): 74–80. Retrieved 21 April 2013.
- CIRVA committee, Report of the Fourth Meeting of the International Committee for the Recovery of the Vaquita (CIRVA). IUCN. 2012
- Rojas-Bracho, L. and B. L. Taylor. Risk factors affecting the vaquita (Phocoena sinus). Marine Mammal Science 15:974-989
- General references
- Preventing the extinction of a small population: Vaquita fishery mortality and mitigation strategies D'Agrosa, Lennert and Vidal. Conservational Biology vol 14. pages 1110-1119
- National Audubon Society: Guide to Marine Mammals of the World, Reeves et al. 2002, ISBN 0-375-41141-0
- Convention on Migratory Species
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