Experts propose keeping some in captivity as a last resort.
SAN FELIPE, Mexico — In the shallow sea waters of the Gulf of California swims a porpoise that few have seen, its numbers dwindling so fast that its very existence is now in peril.
Known mostly by its Spanish name, the snub-nosed vaquita is the world’s smallest cetacean, a miniature porpoise with a cartoonlike features and dark smudges around its eyes. The species lives only in the fertile waters of the gulf’s northern corner.
The size of its population has always been precarious, but now voracious demand in China for a fish that shares the vaquita’s only habitat has pushed the tiny porpoise to the brink of extinction.
No more than 30 vaquitas are left, according to a November estimate based on monitoring of their echolocation clicks. Half of the vaquitas counted a year earlier have disappeared.
This calamity has hardly gone unnoticed. The vaquita has been vanishing in plain sight, to the despair of conservationists who have been advising the Mexican government on how to save it. All of the resources brought to bear, including the protection of the Mexican Navy, have proved to be no match against the illegal wildlife trade.
“If we continue on the path we’re on, we’ll have no vaquitas in two years,” said Barbara Taylor, a marine mammal expert at the National Oceanic and Atmospheric Administration.
The vaquita are simply bycatch, trapped and drowned in curtains of illegal gillnets set for an endangered fish called the totoaba. The fish’s swim bladder is dried and smuggled to China, where wealthy diners pay thousands of dollars for the delicacy, believing it to have medicinal powers.
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| Vaquitas in the Gulf of California. No more than 30 vaquitas are left, according to a November estimate based on monitoring of their echolocation clicks. Credit Paula Olson/NOAA |
To feed that appetite, totoaba poachers have killed 90 percent of the vaquita population since 2011, according to the acoustic monitoring program led by Armando Jaramillo Legorreta at the Mexican government’s National Ecology and Climate Change Institute, known as INECC.
With so few vaquitas left, experts advising the Mexican government have proposed capturing several specimens and holding them in a sea pen as a way of conserving the species until the threat to its habitat is removed. It’s a last-ditch measure that conservationists had hoped they would never have to resort to.
“We had always been opposed to captivity,” said Lorenzo Rojas Bracho, a marine mammal expert at INECC and the chairman of an advisory group, the International Committee for Vaquita Recovery. But nobody expected that the population would decline so quickly.
“There are risks,” Dr. Rojas Bracho said of the capture plan. “But they are fewer than leaving them with the fishing as it is.”
The plan would entail training United States Navy dolphins to locate vaquitas, capturing them for transfer to a temporary pool and then to a sea pen to be built in their habitat along the Gulf of California coast. The majority of vaquitas would remain in the wild.
But the unknowns loom large. “We don’t know whether they find them,” Dr. Taylor said of the dolphins. “We don’t know whether we can catch them. We don’t know how they will react.”
“If you get a negative result in any one of these steps,” she added, “it’s basically game over” for the capture plan. Even in the best of scenarios, breeding in captivity is unlikely to restore the population. A female vaquita gives birth to one calf every two years on average.
If the proposal goes forward, the vaquita would join other species at the brink of extinction — like the California condor and the golden lion tamarin, in Brazil — that are being closely managed in some form distinct from their natural setting. It would be the first such effort for a marine mammal.
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