Vaquita

The vaquita, a small porpoise endemic to Mexico's Gulf of California, is the world's smallest and most endangered small marine cetacean. With fewer than 100 left, high levels of entanglement in fishing gear threaten imminent extinction if current trends continue.

Each year, anywhere between 40 and 80 vaquitas are killed in gillnets and trawl nets used in both artisanal and commercial fishing. At the same time, the habitat of the species has been altered by damming of the Colorado River in the US.

Physical Description

The vaquita is the smallest living cetacean, closely resembling the common porpoise. However, the pectoral fins of this species are longer, and the dorsal fin taller in proportion to the body length, than in other species of porpoise.

Size

The vaquita may weigh up to 55 kg (120 lb) and females can reach up to 1.5 m (4.9'), males up to 1.4 m (4.6').

Colour

In adults, the dorsal surface is dark gray, the sides are pale gray and the ventral surface is white with some long, light gray markings. This porpoise has a large dark ring around the eyes and dark patches on the lips that form a thin line from the mouth to the pectoral fins.

In the newborn, the coloration is darker than in adults, particularly in the head and in the areas behind the eyes. There is a wide gray fringe of color that runs from the head to the dorsal flukes, passing through the dorsal and pectoral fins.

Ecology and Habitat

Squid, crab and fish for breakfast

Vaquitas are found in the open sea, and shallows areas less than 6 m deep at low tide, including sea bays and straits.

Social Structure

The species is usually seen alone or in groups of 2 to 4 individuals, although groups of up to 10 animals have been reported. Being elusive by nature, the vaquita is difficult to observe.

Life Cycle

Little is known about the age at which vaquitas reach sexual maturity, their longevity, reproductive cycle or their population dynamics. Some estimates of these data have been made, however, based on stranded animals, animals tangled in nets and sightings at sea.

Information obtained from other species of porpoises has also been used to try to understand their life cycle. It is thought that vaquitas reach sexual maturity at around six years of age. The female has only one calf in the spring, probably every two years or more. It is believed that vaquitas live up to 22 years.

Breeding

Reproduction takes place in spring or summer, with births following around spring. A female probably produces 1 calf every two years after a gestation period estimated at 11 months, and the young are nursed from 6 to 8 months.

Diet

This cetacean is reported to feed on squid, croakers, fish and crabs among others.

Population and Distribution

...and then the fisheries scaled up

Previous population and distribution

The vaquita was possibly abundant throughout the Gulf of California in the early 20th century, until the commercial fisheries operations scaled-up and were modernized in the 1940's. Its present distribution dates back to the early 1980's.

Current population and distribution

The vaquita is endemic to the upper Gulf of California, Mexico, and its distribution is restricted to an area to the North of Puertecitos, near Rocas Consag Island and El Golfo de Santa Clara and around and north of Puerto Peñasco.

What are the main threats to the Vaquita

Incidental mortality, great losses...

Directed fishing, accidental bycatch in nets set for fish and reduction of food supplies due to fishing threaten this species.

In addition, the vaquita is possibly affected by reductions in water flow into the Gulf of California from the Colorado River, and pesticide pollution is suspected as a potential problem.

Fisheries bycatch

Commercial and artisanal fishing being intensive in the upper Gulf, notably for shrimp, sharks and scombrids, the vaquita is particularly vulnerable to incidental mortality in gill nets. Since they need to surface to breath air, when they get entangled in fishing nets they cannot surface to breath and they drown.

Even though it is known that vaquitas die in all types of nets, it has been difficult to estimate the exact mortality in each type. A study by CEDO of the upper Gulf of California determined that the fishing effort is different in each community in the region, and that the fisheries are dynamic and respond to changes of tides, seasons and other environmental factors, as well as economic factors.

Habitat loss and degradation

This porpoise's habitat has been drastically altered by damming of the Colorado River in the United States. Long-term changes due to the reduced freshwater input are matters of concern and should be investigated.

Throughout the upper Gulf, coastal development is growing and uncontrolled. The coastal zones of estuaries are especially important for the growth of larvae of both non-commercial and commercially important fisheries species. Unfortunately, estuaries are the targets for development such as marinas.

The dragging of trawl nets to capture shrimp results in the destruction of the sea floor and its ecology. The removal of enormous tonnage of fauna, in many cases containing juvenile stages of many species of fish, has disturbed the benthic food web.

Investigators believe that this effect is drastic, considering that shrimp bycatch is many times greater than the amount of shrimp captured. Most of the shrimp bycatch, predominantly fish, die on the boats and are discarded. 

Pesticide pollution

The tributaries of the Colorado River drain through the agricultural lands of Southern California and the Mexicali valley. A potential problem is the presence of organic compounds and chemical fertilizers, which concentrate in the watershed. High levels of pesticides have been related to reproductive incapacity in various marine mammals. However, the most recent analyses indicate that the chlorinated organic compounds and pesticides found in mollusks collected in El Golfo de Santa Clara and near San Felipe are in low concentrations.

The accumulation of contaminants in vaquita and other organisms that inhabit the delta remains a concern. While the results of eight samples of blubber, liver, heart and kidneys from vaquita suggest that the levels of contaminants are low, the presence of possible effects from these contaminants on the species cannot be overlooked.

Natural factors

White sharks, mako, blacktips as well as other shark species have been found with vaquita parts inside their stomachs. Some vaquita tangled in nets showed scars on their flukes from teeth that could be shark or killer whale, and there have been sightings of killer whales and also of other species of sharks, like the tiger shark (Galeocerdo cuvier), scalloped hammerhead sharks (Sphyrna spp.) and bull shark (Charcharhinus leucas), among others. However there have been no direct reports of attacks on vaquita by these species of sharks or by killer whales.

How you can help

• Support efforts to improve fishing gear by only buying seafood that is MSC certified. This can help to reduce the incidence of marine bycatch, which kills whales and other marine life like turtles, dolphins, and seabirds.
   
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