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= Vaquita = From Wikipedia, the free encyclopedia

The vaquita (Phocoena sinus) is a species of porpoise endemic to the northern end of the Gulf of California in Baja California, Mexico. Averaging 150 cm (females) or 140 cm (males) in length, it is the smallest of all living cetaceans. The species is currently on the brink of extinction, and currently listed as Critically Endangered by the IUCN Red List; the steep decline in abundance is primarily due to bycatch in gillnets from the illegal totoaba fishery.

Taxonomy
The vaquita was first described as a species by two zoologists, Kenneth S. Norris and William N. McFarland, in 1958 after studying the morphology of skull specimens found on the beach. It was not until nearly thirty years later, in 1985, that fresh specimens allowed scientists to describe their external appearance fully.

The genus Phocoena comprises four species of porpoise, most of which inhabit coastal waters (the spectacled porpoise is more oceanic). The vaquita is most closely related to Burmeister's porpoise (Phocoena spinipinnis) and less so to the spectacled porpoise (Phocoena dioptrica), two species limited to the Southern Hemisphere.

The vaquitas current habitat range was likely reduced or rendered entirely absent by decreases in sea level over the last 350,000 years, though sea levels reached a low during the Saalian glacial period, which fell squarely within the Penultimate Glacial Period , and the Last Glacial Maximum (LGM), followed by a significant rise during the Eemian warm period and after the LGM.

'''There is no fossil evidence that the vaquita ever inhabited the colder parts of the eastern North Pacific, including the Baja California coast and offshore regions. Because the Burmeisters and Spectacled porpoises are both native to temperate waters of the southern hemisphere, and based on the timing of sea level and vaquita population decline, it is thought that climate change brought by the Saalian Glacial Period caused northward migration of the vaquita into the newly expanded and productive gulf of California, where they persist to this day.'''

Genome sequencing from an individual captured in 2017 indicates that the ancestral vaquitas had already gone through a major population bottleneck in the past, which may explain why the few remaining individuals are still healthy despite the very low population size.

"Vaquita" is Spanish for "little cow".

Description
The smallest living species of cetacean, the vaquita can be easily distinguished from any other species in its range. It has a small body with an unusually tall, triangular dorsal fin, a rounded head, and no distinguished beak. The coloration is mostly grey with a darker back and a white ventral field. Prominent black patches surround its lips and eyes. Sexual dimorphism is apparent in body size, with mature females being longer than males and having larger heads and wider flippers. Females reach a maximum size of about 150 cm, while males reach about 140 cm. Dorsal fin height is greater in males than in females. They are also known to be around 60-150 pounds. This makes them one of the smallest species in the porpoise family.

Distribution and habitat
Vaquita habitat is restricted to a small portion of the upper Gulf of California (also called the Sea of Cortez), making this the smallest range of any marine mammal species. They live in shallow, turbid waters of less than 150 m depth. Vaquitas inhabit murky warm waters within 16 miles of the shoreline since there is high food availability and a strong tidal mix. Since they are able to survive in shallow waters, their triangle-shaped dorsal fin sticks out above water and they are commonly mistaken for dolphins (Center for Biological Diversity, n.d).

Diet
Vaquitas are generalists, foraging on a variety of demersal fish species, crustaceans, and squids, though benthic fish such as grunts and croakers make up most of the diet.

Social behavior
Vaquitas are generally seen alone or in pairs, often with a calf, but have been observed in small groups of up to 10 individuals.

Little is known about the life history of this species. Life expectancy is estimated at about 20 years and age of sexual maturity is somewhere between 3 and 6 years of age. While an initial analysis of stranded vaquitas estimated a two-year calving interval, recent sightings data suggest that vaquitas can reproduce annually. It is thought that vaquitas have a polygynous mating system in which males compete for females. This competition is evidenced by the presence of sexual dimorphism (females are larger than males), small group sizes, and large testes (accounting for nearly 3% of body mass).

Population status
Because the vaquita was only fully described in the late 1980s, historical abundance is unknown.

'''Genomic analysis indicates that the effective vaquita population size has been small, ranging from approximately 1400 to 3200 for the last 300,000 years. The population likely declined during the late Pleistocene due to climate change and related habitat changes in the eastern North Pacific.'''

The first comprehensive vaquita survey throughout their range took place in 1997 and estimated a population of 567 individuals. By 2007 abundance was estimated to have dropped to 150. Population abundance as of 2018 was estimated at less than 19 individuals. Given the continued rate of bycatch and low reproductive output from a small population, it is estimated that there are fewer than 10 vaquitas alive as of February 2022.

Reproduction
Vaquitas reach sexual maturity from three to six years old. Vaquitas have synchronous reproduction, suggesting that calving span is greater than a year. Their pregnancies last from 10 to 11 months. Vaquitas give birth about every other year to a single calf. They give birth between the months of February and April.

Fisheries bycatch
The drastic decline in vaquita abundance is the result of fisheries bycatch in commercial and illegal gillnets, including fisheries targeting the now-endangered Totoaba, shrimp, and other available fish species. Despite government regulations, including a partial gillnet ban in 2015 and establishment of a permanent gillnet exclusion zone in 2017, illegal totaoba fishing remains prevalent in vaquita habitat, and as a result the population has continued to decline. The vaquita is the most critically endangered marine mammal, with fewer than 19 remaining in the wild. First described in 1958, the vaquita has been in rapid decline for more than 20 years resulting from inadvertent deaths due to the increasing use of large-mesh gillnets.

In 2021, the Mexican government eliminated a "no tolerance" zone in the Upper Gulf of California and opened it up to fishing.

Other threats
Given their proximity to the coast, vaquitas are exposed to habitat alteration and pollution from runoff. Bycatch is the single biggest threat to the survival of the few remaining vaquita. Exposure to toxic compounds has also had a deleterious effect on vaquitas.

'''While some claim that the reduced flow of fresh water from the Colorado River caused by the construction of the Hoover Dam has a negative effect on the health of vaquita populations, there is no evidence indicating that this is the case. This idea deflects from the primary threats to the vaquitas survival - fisheries bycatch.''' Predation on vaquita by sharks has also been reported from fishermen, who have seen whole or parts of individuals in the stomachs of caught sharks, although no quantitative analysis is readily available. However, the biggest threat still towards vaquita are fisheries. Northern fishing fleets have had an indirect positive impact mainly on marine mammals, because fishing on predators like sharks reduces its predatory negative impact on those groups. Although the predation of sharks towards vaquita do result in a decline in population and is seen as an alternate threat, northern fishing fleets also negatively impact this small marine mammal because the negative influence of incidental catch is greater than the positive influence of predation reduction by shark fisheries.

Attempts to start a population in captivity have proved to be more threatening to the population than helpful. A November 2017 effort ended up traumatizing and killing one female vaquita, as well as invoking unnecessary stress onto a juvenile.

Conservation status
The vaquita is listed as critically endangered on the IUCN Red List. It is considered the most endangered marine mammal in the world.

The species is also protected under the US Endangered Species Act, the Mexican Official Standard NOM-059 (Norma Oficial Mexicana), and Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Conservation efforts
The Mexican government, international committees, scientists, and conservation groups have recommended and implemented plans to help reduce the rate of bycatch, enforce gillnet bans, and promote population recovery.

Mexico launched a program in 2008 called PACE-VAQUITA in an effort to enforce the gillnet ban in the Biosphere Reserve, allow fishermen to swap their gillnets for vaquita-safe fishing gear, and provide economic support to fishermen for surrendering fishing permits and pursuing alternative livelihoods. '''The efficacy of PACE-Vaquita was largely dependant on several factors, chiefly the gender and locality of the participant, and whether or not the participant also received a loan outside of the PACE-Vaquita program. It was found that the participant was more likely to remain in their alternative lifestyle if they were a woman residing in the community of San Felipe whos alternative lifestyle was also partially funded by a loan outside of the PACE-Vaquita program.''' Despite the progress made with legal fishermen, hundreds of poachers continued to fish in the exclusion zone.

'''These management actions polarized those in the industry and created a large rift between the fisheries and conservation sectors. These rifts have been made worse by fishers being excluded from the development of new conservation strategies, like the creation of vaquita-safe trawls and nets, while still being expected to collaborate in data collection.'''

Many fishers were hesitant to use the new vaquita-safe gear, as standard gill nets are considerably more efficient at catching shrimp; gillnets caught an average of 3.2 times more shrimp than the RSINP trawlers, which caught a similar amount to the modified trawler nets.

'''Gillnets also covered nearly twice the area and caught a much higher biomass of shrimp per unit area, as well as a much higher rate of both incidental and unusable bycatch. Consequently, both the RSINP and modified trawlers used almost 30% more fuel per working trip than the gillnets.'''

With continued illegal totoaba fishing, which is largely motivated by sales to the Chinese market where it is used in traditional medicine, and uncontrolled bycatch of vaquitas, the International Committee for the Recovery of the Vaquita (CIRVA) recommended that some vaquitas be removed from the high-density fishing area and be relocated to protected sea pens. This effort, called VaquitaCPR, captured two vaquitas in 2017: One was later released and the other died shortly after capture after both suffered from shock.

Local and international conservation groups, including Museo de Ballena and Sea Shepherd Conservation Society, are working with the Mexican Navy to detect fishing in the Refuge Area and remove illegal gillnets. In March 2020, the U.S. National Marine Fisheries Service (NMFS) announced a ban on imported Mexican shrimp and other seafood caught in vaquita habitat in the northern Gulf of California.

In response to the dire circumstances facing the vaquita as by-catch of the illegal totoaba trade, in 2017 Earth League International (ELI) commenced an investigation and intelligence gathering operation called Operation Fake Gold, during which the entire illicit totoaba maw (swim bladder) international supply chain, from Mexico to China, has been mapped and researched. Thanks to the confidential data that ELI shared with the Mexican authorities, in November 2020, a series of important arrests were made in Mexico.

To date, efforts have been unsuccessful in solving the complex socioeconomic and environmental issues that affect vaquita conservation and the greater Gulf of California ecosystem. Necessary action includes habitat protection, resource management, education, fisheries enforcement, alternative livelihoods for fishermen, and raising awareness of the vaquita and associated issues.

The Secretariat of Environment and Natural Resources (SEMARNAT) announced on February 27, 2021, that it may reduce the protected area for the vaquita in the Sea of Cortés as there are only ten of the porpoises left and it may never recuperate its historical range.

'''In March of 2022, The Standing Committee of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) voted in favor of permitting the trade of captive-bred totoaba. Critics argue that this would provide cover for illegal wild-sourced totoaba trade, which could be harmful for the few remaining vaquitas.'''

Consumers
Consumers in America play a role in the endangerment of the vaquitas due to consumption of shrimp with a high aquatic mammal bycatch rate, and roughly 80% of shrimp caught in the northern end of the Gulf of California is consumed in the United States. Efforts can be made to save endangered species like the vaquita through the use of market restrictions on problematic goods. The Marine Animal Protection Act of 1972, which forbids foreign fishers from exporting seafood with high levels of marine mammal bycatch, may allow for better efforts to preserve endangered vaquitas.