Phocoena sinus Norris & McFarland 1958

The vaquita is an elusive marine mammal, which surfaces slowly, barely disturbing the water's surface when it breathes and then quickly disappearing for long periods (8). It cryptic behaviour and rarity may be the reasons why little is known about the biology of the vaquita, except that most vaquita births occur around March, gestation is believed to last around 10 to 11 months and one individual was estimated to have lived for 21 years (2). Little is also known about the social organisation of this enigmatic species (2). While the vaquita is most often seen in schools of one to three individuals (8), groups as large as eight or ten have been seen, and these small schools may form large, loose aggregations for short periods (2). The vaquita has a varied diet, comprising fish that live on or near the ocean bottom, squid and crustaceans. Like other cetaceans, the vaquita produces high-frequency clicks which are used in echolocation. This may be used to locate their prey, but several of the fish species it feeds on are known to produce sound and so it is possible that the vaquita locates them by following their sound, rather than by echolocating. In the murky waters of its habitat, echolocation may also be used to communicate with other vaquitas (2).

Time is quickly running out for the vaquita, with a group of scientists in 2007 stating that they believed there were only two years remaining in which to find a solution to saving this species (4). Some measures have already been implemented; the Mexican government created the Upper Gulf of California and Colorado River Delta Biosphere Reserve in 1993 to protect the vaquita and other endangered species (2). In 2005, the Government also created a vaquita reserve, the area of which partially overlaps with the Biosphere Reserve (10). A ban on gillnet fishing is currently being enforced within the vaquita reserve, but gillnetting and shrimp trawling continues in the Biosphere Reserve and elsewhere within the range of vaquita (10) (11). Whilst these are incredibly important steps in the battle to save the vaquita, if conservation efforts are not increased substantially the vaquita will become extinct (7). The Mexican government created the International Committee for the Recovery of the Vaquita (CIRVA): a group of scientists from the UK, Canada, US and Mexico (2). CIRVA recommends that the most critical measure for the conservation of the vaquita is to reduce by-catch to zero as soon as possible (2). This will need to be achieved by banning the use of all entangling fishing nets within the vaquitas range. Unfortunately, this is not an easy law to implement, as this will have a serious impact on the people whose livelihoods depend on fishing in the Gulf of California (2) (4). Funds are urgently needed to buy out these net fisheries and to develop economic alternatives for those people affected (4) (10). One can only hope that lessons are learnt from the tragic tale of the baiji and that necessary measures are implemented before the vaquita too is driven to extinction.

Since the baiji (Lipotes vexillifer) was believed to have become extinct in 2006 (3), the vaquita has taken on the unfortunate title as the most endangered cetacean in the world (4). It also has the distinction of being the smallest porpoise species (2), a group of marine mammals that differ from dolphins in their stockier, robust body, lack of an elongated beak, and their distinctively shaped teeth (5). The vaquita has a dark grey back and pale grey sides, blending into white on the underside, and there are highly conspicuous large black rings around its eyes and mouth. The fin on the back of its body, the dorsal fin, is proportionally taller than that of other porpoises and is roughly triangular, but curves slightly backwards (6).

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. Its habitat is characterised by turbid water with a high nutrient content (2).

Endemic to the upper Gulf of California, Mexico (2) (7).

Classified as Critically Endangered (CR) on the IUCN Red List (1).

It was estimated in 2007 that only around 150 vaquita remained in the world (4); a number that is declining rapidly as the species is impacted by significant threats (7). The upper Gulf of California is not only home to this Critically Endangered species, it is also the site of intensive commercial and artisanal fishing (7). Vaquitas become entangled in the gill nets and trawl nets that are used in these activities, claiming the lives of an estimated 39 to 84 vaquitas each year (2). This is considered the principal threat to the vaquita's survival (7). The habitat of the vaquita has undoubtedly been changed by the damming of the Colorado River in the United States and the resulting loss of its flow into the Gulf of California; however, the Gulf remains incredibly productive and loss of river input is not believed to be an immediate threat to the vaquita (9).