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Captured vaquitas will be housed in a sea pen until a sanctuary is set up.

Flip Nicklin/Minden Pictures/National Geographic Creative

Update: After death of captured vaquita, conservationists call off rescue effort

On Friday, VaquitaCPR, the $5 million last-ditch effort by the Mexican government and conservationists to capture a rare porpoise called the vaquita, will formally announce the end of the project. The team captured two vaquitas: One, a calf, had to be released because it was stressed; the other, an adult female, died before it could be released. Since that death on 5 November, the 67-person team stopped trying to capture this diminutive cetacean. Instead, it has focused on trying to get detailed photographs of the 15 or so animals that still exist in the Gulf of California, their only habitat, so they can keep better track of the animals.

Continually plagued by bad weather, the project was halted because the vaquitas reacted poorly to being placed in the sea pen designed to house them. That persuaded researchers that capturing the animals was not worth the risk. “There’s nothing worse than having an animal die in your hands,” says Frances Gulland, the lead VaquitaCPR veterinarian and a scientist at The Marine Mammal Center in Sausalito, California. 

The rescue attempt came about because illegal poaching of a fish highly prized for its swim bladder. The vaquitas become entangled and drown in the fishing nets. Despite efforts by the Mexican government to stop fishing where the vaquitas live, their numbers have dropped precipitously. With bringing vaquitas into captivity off the table for now as a solution, “what has to happen is the ramping up of enforcement” against poachers, Gulland says. 

Here are our earlier stories:

6 November: The effort to prevent the extinction of a rare porpoise found only in the Gulf of California suffered a major setback last week. A captured female vaquita died on 4 November, despite best efforts by a veterinary team, after being released into a sea pen where she would have been kept until the Gulf was made safer for this marine mammal. This was the second animal captured. The first, a young vaquita, was released almost immediately because it was showing signs of stress. The team had attempted to release the second vaquita, but it died before it could be freed, and "life-saving measures were unsuccessful," VaquitaCPR reported in a press release.  “With less than 30 vaquitas left on Earth, the entire rescue team is heartbroken by this devastating loss."  The rescue operation had been delayed more than a week because of poor weather. Now, the team is reviewing the procedures they followed to decide how to continue.

12 October: With four trained U.S. Navy dolphins acting like herding dogs and an array of special nets, enclosures, and stretchers, conservationists today began their roundup of the vaquita, a porpoise that lives in the upper Gulf of California. Only an estimated 30 vaquitas are left in the wild, and those numbers have been dwindling despite efforts by the Mexican government to ban fishing with gillnets, which inadvertently trap and drown these marine mammals. So as a final, desperate measure, the International Committee for the Recovery of the Vaquita and the Mexican government brought a team of experts to San Felipe, Mexico, to try to locate at least some of the vaquitas and corral them in nets. They hope to transfer 10 to 12 of these rare survivors to a temporary sanctuary—a sea pen off San Felipe—and eventually to release them in a part of the gulf that’s been cleared of gillnets and illegal fishing activity. The rescue effort, Vaquita CPR, will last 2 weeks, program spokesperson Steve Walker says. The strategy—first proposed by biologists last year—is a risky endeavor because porpoises, unlike dolphins, tend to be very sensitive and are hard to keep in captivity. But recent successes, including the captive breeding of harbor porpoises rehabilitated after being tangled in nets or stranded, gives the team hope of reviving the species.