Aquarium of the Pacific - Online Learning Center - Species Print Sheet
In addition to being the smallest member of the porpoise family, vaquita are the smallest of all known cetaceans, have the most restricted range, and are the most critically endangered of all cetaceans. Native to Mexico, their scientific name, Phocoena sinus means “porpoise of the gulf”. Vaquita is Spanish for “little cow”. Their other common names are Gulf of California harbor porpoise, cochito, and vaquita marina. They were not discovered or named until 1958 when three skulls were found on the beach. More than 40 years later little is known about their natural history, and they may become extinct before more is known. Current knowledge is based on sightings of live animals, observations of stranded or trapped animals, and necropsies.
At the Aquarium
Due to the space requirements for these intelligent and dynamic animals, we do not exhibit live cetaceans. This information is available for a reference.
Restricted to northwestern corner of Gulf of California (Sea of Cortez) and, perhaps, the Colorado River Delta.
Vaquita live in shallow lagoons no more than 25 km (16 mi) from shore where there is a strong tidal mix. Although they can survive in lagoons that are so shallow that their back protrudes above the surface of the water, they prefer water that is 10 to 28 m (33 to 92 ft) deep.
Vaquita have the typical robust body shape of a porpoise with the middle of the body measuring about 68% of the body length. They have little or no beak with a slight protrusion of the upper jaw at the base of the melon. Their dorsal fin is upright with a straight vertical or slightly curved (falcate) rear margin and bumps and whitish spots on the leading edge. Their dorsal fin is relatively large when compared to that of other porpoise species.
They are dark gray on their upper body and halfway down their sides where the coloration fades to a lighter gray. The throat and belly are streaked with white. There is a dark stripe extending from the middle of the lower jaw to the front of the flippers. They have black eye and chin patches and black lips. Juveniles are darker than adults.
Adults are 1.2-1.5 m (3.9-4.9 ft) long and weigh about 45 to 50 kg (99 to 110 lb). Females tend to be larger than males.
Examination of stomach contents of dead animals has shown that vaquitas are not picky about their diet, eating a variety of fish species (17 species found in one animal) that live near or on the gulf bottom. They also eat squid and crabs.
Little is known about vaquita reproduction but researchers believe it is probably similar to that of harbor porpoises. If that is true, then sexual maturity is reached at three to five years of age and the gestation period is probably about 11 months. Births occur in February-April, peaking in late March to early April. Newborn calves are 70-78 cm (31-38 in) long and weigh 7.5 kg (17 lb). The calf probably nurses for six to eight months.
Many scientists believe that vaquita will become extinct because the genetic pool is too small for effective reproduction
Vaquita are shy, rather secretive animals. They have been observed singly, in pairs, and in groups of up to seven animals. They generally do not engage in acrobatics at the surface of the water, emerging from beneath the surface with a slow, forward-rolling movement that barely disturbs the water’s surface, taking a breath, and then quickly disappearing in a quiet dive.
These porpoises echolocate using a series of high frequency clicks.
The closest porpoise species to vaquita geographically is central California’s harbor porpoise which is 2500 km (1500 mi) distant, however, they are more closely related morphologically to Burmeister’s porpoise which occur from Peru southward, 5000 km (3000 mi) away. It is thought that vaquita evolved from an ancestral population of Burmeister’s porpoise that moved northward into the Gulf of California one million years ago.
Vaquitas are the only porpoise species adapted to living in warm water. Most porpoises inhabit water that is cooler than 20oC (68oF) whereas vaquita are able to tolerate water that fluctuates from 14oC (57oF) in the winter to 36oC (97oF) in the summer.
These porpoises may live 20 years if they escape gillnets.
In general porpoises are very prone to entanglement in fishing nets. This is undoubtedly the reason why vaquita are critically endangered today and believed by many scientists to be on the brink of extinction. They share their upper Gulf of California (Sea of Cortez) habitat with totoaba, a large sea bass. Commercial fishing for the fish, which started in 1930 and peaked in 1942, was done with large-mesh gillnets, deadly fishing gear for air-breathing marine mammals and turtles and for other incidental catch. The commercial fishery closed in 1970 but that did not solve the problems for vaquita.
Mexico banned fishing for totoaba in 1975, placed totoaba on the country’s endangered species list in 1977 and vaquita in 1978, and banned large mesh gillnets in 1992. Although Mexico established the Upper Gulf of California and Colorado River Biosphere Reserve in 1993 to provide some measure of protection for vaquita, totoaba, sea turtles, and other wildlife, illegal fishing for totoaba continues and along with it the entrapment of vaquita in the fishing nets. Also, 40% of the range of vaquita is outside the boundary of the reserve where legal fishing does occur. They continue to be drowned in the small mesh gillnets used legally to catch sharks, Spanish mackerel, sierra, chano, and other species, and by shrimp trawling nets. The current best estimate of today’s vaquita population is only 500-600 animals with 40-80 animals in the population drowned in fishing nets each year, trapped as incidental or bycatch.
Some scientists believe that vaquita (also bottlenose dolphin) have some dependence on water flow from the fresh water Colorado River delta for feeding grounds. Today because of dams in the United States and dependence of seven U. S. states plus Mexico on the river for agricultural and municipal drinking water, the river flows only in times of El Nino weather patterns to provide breeding grounds and nurseries for shrimp and fish larvae, part of the diet of both cetaceans.
Vaquita are listed as critically endangered by the IUCN-World Conservation Union (IUCN) In the United States they are protected by the Marine Mammal Protection Act of 1972 and have been listed as endangered under the Endangered Species Act since 1985. The United States banned importation of totoaba in 1977 but to this day the fish still appears in fish markets in border states.
The terms porpoise and dolphin are often used interchangeably in error. There are differences between the two cetaceans. Porpoises are smaller, more robust, have smaller more triangular dorsal fins, lack a prominent beak, and have spade instead of conical-shaped teeth. Most inhabit shallow, nearshore waters and rarely follow vessels as dolphin often do bowriding or surfing in the wake.