The vaquita (Phocoena sinus) is a small marine mammal belonging to the order Cetacea, suborder Odontoceti, and family Phocoenidae. Endemic to the northern Gulf of California, Mexico, it is the world’s most endangered cetacean, with the IUCN classifying it as Critically Endangered. Adults reach 150–210 cm in length and weigh 45–65 kg, making them the smallest of all porpoises. Their dark gray coloration, rounded dorsal fin, and distinctive facial markings—dark patches around the eyes and a thin line from the mouth to the pectoral fin—aid identification. Vaquitas inhabit shallow, murky coastal waters less than 30 meters deep, preferring estuarine habitats with abundant prey. Their limited range, combined with a fragmented population estimated at fewer than 10 individuals, makes them highly vulnerable to anthropogenic pressures. Conservation efforts focus on eliminating gillnet fisheries, establishing protected zones, and conducting intensive monitoring to prevent the species’ extinction.

Vaquitas are generally shy and elusive, spending most of their time near the surface where they can quickly evade predators. They are primarily solitary or found in very small groups of two to three individuals, often a mother with a calf. Their activity peaks during dawn and dusk, with foraging bouts lasting 30–45 minutes followed by brief surface rests. Home ranges are limited to a few square kilometers within the Upper Gulf, and individuals show strong site fidelity, rarely venturing beyond the core habitat. Communication relies on a repertoire of high‑frequency clicks and burst pulses used for echolocation and social interaction; these sounds are beyond human hearing but can be recorded with specialized equipment. Vaquitas exhibit low aggression, and interactions are mostly limited to mother‑calf bonding and brief social contacts during mating.

The vaquita is a carnivorous specialist, feeding primarily on small pelagic fish such as Pacific anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), and lanternfish (Myctophidae). Cephalopods, especially squid species like Loligo opalescens, and occasional crustaceans supplement the diet. Individuals consume roughly 5% of their body weight daily, equating to 2.5–3.5 kg of prey. Vaquitas employ high‑frequency echolocation clicks to locate prey in the turbid, low‑visibility waters of the Gulf. Their foraging strategy involves short, rapid dives of 2–5 minutes, during which they scan the water column and bottom substrate. Prey capture is achieved through swift lunges and suction feeding, allowing them to ingest fish whole. Seasonal shifts in prey availability can lead to temporary changes in diet composition, but the species remains highly dependent on abundant small fish stocks.

Sexual maturity is reached at 3–4 years for both sexes, with females typically larger and slightly earlier to mature. Breeding occurs opportunistically throughout the year, though peaks have been observed in the winter months. Gestation lasts approximately 10–11 months, after which a single calf is born, weighing about 5–6 kg and measuring 55–65 cm. Calves are nursed for 6–8 months, during which they rely entirely on their mother’s milk before transitioning to solid prey. Maternal care is intensive; mothers protect calves from predators and guide them to productive foraging grounds. Weaning coincides with the calf’s ability to perform independent echolocation. Reproductive rates are low, with females producing a single offspring every 2–3 years, a factor that hampers population recovery under current threat levels.

The vaquita is listed as Critically Endangered by the IUCN, with the most recent population estimate (2023) indicating fewer than 10 mature individuals remaining. The primary threat is incidental capture (bycatch) in illegal gillnet fisheries targeting the endangered totoaba (Totoaba macdonaldi) for its prized swim bladder. Gillnets entangle vaquitas, leading to drowning as they cannot surface for air. Despite a 2015 ban on gillnet use in the Upper Gulf, enforcement is weak, and illegal nets persist. Habitat degradation from coastal development, pollution, and reduced prey availability due to overfishing further exacerbate the decline. Climate change may alter water temperature and prey distribution, adding additional stress. Conservation actions include a total gillnet ban, establishment of a marine protected area, intensive patrols, and a captive‑breeding feasibility study, though no individuals have ever survived in captivity. Without immediate and effective mitigation, extinction is imminent.

• The vaquita is the smallest and most endangered cetacean in the world.
• It was only scientifically described in 1958, making it a relatively recent discovery.
• Vaquitas have a unique facial marking: a dark ring around each eye and a thin line from the mouth to the pectoral fin.
• Their echolocation clicks can reach frequencies up to 130 kHz, far beyond human hearing.
• Despite intensive conservation efforts, the species’ population has declined by over 95% since the 1990s.