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).