World's Smallest Porpoise Nearly Extinct, Experts Say
for National Geographic News
|December 19, 2006|
The recently declared extinction of the Chinese river dolphin has focused
attention on the plight of another imperiled marine mammal—the
world's smallest porpoise.
Found only in waters off Mexico, the vaquita may now be the most endangered of any whale or dolphin species, due to the animal's frequent and fatal entanglements in fishing nets, experts say.
The International Committee for the Recovery of the Vaquita (CIRVA), a conservation research group, estimates only 250 to 400 of the elusive marine mammals remain.
Those numbers, if accurate, mean the vaquita is on a trajectory toward extinction. The last full survey, conducted in 1997, estimated its total population at 567.
Vaquitas occupy a small area in the northern Gulf of California, between the Baja California peninsula and the mainland of Mexico (see Mexico map).
The animals remain highly threatened by fishing and shrimp harvesting in the region, according to an overview of the species' status published this summer in the quarterly journal Mammal Review.
The study, led by Lorenzo Rojas Bracho of Mexico's National Institute of Ecology in Ensenada, notes that the vaquita's actual numbers are uncertain. The animal is notoriously difficult to detect and observe, making an accurate census nearly impossible.
But between 39 and 78 vaquitas are killed each year due to entrapment in fishing nets, Rojas Bracho said.
That number exceeds the estimated number of yearly births, providing the basis for the team's lowered population estimate.
A new survey being conducted by Rojas Bracho and colleagues largely agrees with the CIRVA estimate.
"Our results point to a 30 percent population reduction [since 1997]," Rojas Bracho said.
The Price of Fish
The vaquita is smallest of all the world's cetaceans—the order of animals that includes whales, dolphins, and porpoises.
The Mexican mammal is also perhaps the most seldom seen cetacean. Found within only 850 square miles (2,200 square kilometers) of the Gulf of California, the 5-foot-long (1.5-meter-long) animal was discovered by scientists only in 1958.
With its tiny range, the vaquita has probably always been small in number. But fishing has almost certainly caused the species to decline, perhaps beyond the point from which it can recover, scientists say.
Like other marine mammals, vaquitas can become entangled in fishing nets and drown when they are unable to swim to the surface to breathe.
Rojas Bracho said that, despite efforts to protect the species, "fishing effort has increased, and illegal fishing is a problem. So the risk factor has gone up."
In an attempt to protect the species, conservationists established a reserve area in the northern Gulf of California in 1993. But recent studies have shown that most vaquitas live outside of the reserve's zone of protection.
A new marine reserve established late last year by the Mexican government may offer more hope. The reserve bans certain types of fishing in an area where nearly 80 percent of vaquita sightings have occurred.
At the same time Mexico granted the equivalent of a million U.S. dollars to the state governments of Sonora and Baja California to compensate affected fishers.
Peggy Boyer is the director of the Intercultural Center for the Study of Deserts and Oceans, a Sonora-based research and conservation organization.
Her group is working with fishing communities to minimize adverse effects of the new reserve on the coastal economy and to develop alternative sources of income.
For example, in one community, part of the compensation money from the government may be used to promote ecotourism.
If the plan is approved, she said, "fishermen who retire their boats will receive new boats with more environmentally friendly motors outfitted for serving tourists rather than fishing."
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