Conservation plan involves sending dolphins into Gulf of California to find vaquita and then surface to raise the alarm

US Navy-trained dolphins and their handlers will participate in a last-ditch effort to catch the last few dozen of Mexico’s vaquita porpoises to save them from extinction.

The trained animals will use their sonar to locate the extremely elusive vaquitas, then surface and advise their handlers.

The number of vaquitas, the world’s smallest and most endangered porpoise species, has been devastated by illegal fishing for the swim bladder of the totoaba, a fish which is a prized delicacy in China.

According to rough estimates, with the vaquita population falling by 40% a year, and only 60 alive a year ago, there could be as few as three dozen left.

World's smallest porpoise 'at edge of extinction' as illegal gillnets take toll Read more

Although the vaquita has never been held successfully in captivity, experts hope to put the remaining porpoises in floating pens in a safe bay in the Gulf of California, also known as the Sea of Cortez, where they can be protected and hopefully breed.

International experts confirmed the participation of the navy marine mammal program in the effort, which is expected to start in the spring. Jim Fallin of the US Navy Space and Naval Warfare Systems Center Pacific said on Tuesday the dolphins’ participation was still in the planning stage.

“Their specific task is to locate” vaquitas, which live only in the Gulf of California, Fallin said. “They would signal that by surfacing and returning to the boat from which they were launched.”

The dolphins have been trained by the navy for tasks such as locating sea mines.

Lorenzo Rojas-Bracho, the chairman of the International Committee for the Recovery of the Vaquita, wrote that “an international group of experts, including navy personnel, have been working on two primary goals: determining the feasibility of locating and catching vaquitas, as a phase one. And as a second phase, to determine the feasibility of temporarily housing vaquitas in the Gulf of California.”

Rojas-Bracho said the effort by the international team of experts “would involve locating them, capturing them and putting them in some kind of protective area”, probably a floating enclosure or pen in a protected bay where they would not be endangered by fishing nets. Mexico has banned gillnets that often trap vaquitas in the area, but has had trouble enforcing it because the totoaba draws very high prices on the black market.

“At the current rate of loss, the vaquita will likely decline to extinction by 2022 unless the current gillnet ban is maintained and effectively enforced,” Rojas-Bracho wrote.

Some experts, like Omar Vidal, Mexico’s director of the World Wildlife Fund, oppose the capture plan, which could risk killing the few remaining vaquitas and open up a free-for-all of illegal fishing once they are removed from their natural habitat. “We must strive to save this porpoise where it belongs: in a healthy Upper Gulf of California,” he said.

Catch-and-enclose is risky. The few remaining females could die during capture, dooming the species. Breeding in captivity has successfully saved species such as the red wolf and California condor, but the vaquita has only been scientifically described since the 1950s and has never been bred or even held in captivity.

Experts including Rojas-Bracho; Barbara Taylor, leader of Marine Mammal Genetics Program at the National Oceanic and Atmospheric Administration; and Sarah Mesnick of the NOAA’s Southwest Fisheries Science Center, emphasized that the capture program “should not divert effort and resources away from extension and enforcement of the gillnet ban, which remains the highest-priority conservation actions for the species”.

Veterinarians would evaluate vaquitas’ reactions and release stressed individuals, they wrote. Should a death occur, the team would re-evaluate the sanctuary strategy. “It is important to stress that the recovery team goal is to return vaquita from the temporary sanctuary into a gillnet-free environment,” they wrote.