MEXICO CITY — Gillnet fishing in the upper Sea of Cortez has pushed the vaquita marina, the world's smallest porpoise, to the brink of extinction, according to an environmental report published Friday which states fewer than 100 of them are believed left.
Despite nearly two decades of efforts by Mexico to save the vaquita, new studies using underwater listening devices found only half as many porpoises as were counted in 2012. Experts believe fewer than 25 of the remaining vaquitas are reproductively mature females.
If left unchecked, gillnet fishing and China's insatiable appetite for the swim bladder of the totoaba — another endangered fish hunted in the same area — may seal the fate of the tiny porpoise, according to the report from the International Committee for the Recovery of the Vaquita.
"If there is fishing for totoaba this September, the vaquita might disappear this year," said Omar Vidal of the World Wildlife Fund. "Totoaba nets are the best device to catch vaquitas."
The vaquita porpoise lives in just one place: the upper waters of the sea — also called the Gulf of California — between the Baja California Peninsula and mainland Mexico. They were discovered only in 1958, according to the World Wildlife Fund, and now are considered critically endangered.
Fishery restrictions implemented in Colorado River delta have failed to protect the species, in part because of illegal gillnet fishing for totoaba, a huge, heavy fish whose swim bladder is prized by chefs in China, according to the vaquita recovery committee, which is made up of international experts convened by the Mexican government.
The number of vaquitas counted has dropped steadily since around 2010, when Mexican authorities also noticed an uptick in illegal fishing for totoaba, which is similar to the Chinese bahaba that has been fished almost out of existence.
The bladder of the totoaba is prized by Chinese chefs, who use it to make soups and other dishes. According to the Smithsonian Institution's website, one totoaba bladder can attract a $5,000 payoff in the United States, and more than $10,000 in Asia.
"It's aquatic cocaine," said Jay Barlow, a marine mammal expert at the National Oceanic and Atmospheric Administration. "With two days of fishing, you can buy a new pickup truck."
In 2013 alone, Mexican regulators seized illegal totoaba bladders worth an estimated $2.25 million.
The committee report said the U.S. must play a role, noting "thousands of swim bladders are dried and smuggled out of Mexico, often through the United States. The remainder of the fish is left to rot on the beach."
"The governments of the United States and China must help Mexico eliminate the illegal trade in totoaba products," the report continued. "Unless these steps are taken immediately, the vaquita will follow the Yangtze River dolphin into oblivion and become the second species of whale, dolphin or porpoise driven to extinction in human history."
The Chinese river dolphin, which disappeared in 2006, had more challenging problems, Barlow said, such as severe pollution, overfishing and shipping traffic along the Yangtze.
"It was just a total ecological mess," he said. The northern Sea of Cortez, however, "is relatively pristine and the only thing that's preventing the (vaquita) species from surviving is gillnetting."
The committee urgently recommended extending a total ban on using, possessing or transporting gill nets in the western corner of the upper Sea of Cortez, west of Puerto Penasco. Gill nets have fine mesh and no exclusionary devices of the kind that allow by-catch to escape. They're very large, and often are left out for days, catching everything that swims by. Worse, because the totoaba is protected and fishing for it is illegal, the nets often are strung up surreptitiously at night and left unattended, increasing the potential of catching unintended species.
The report recommended exploring other ways to keep area fishermen employed. It also said the gillnet ban might have to be enforced in fishing towns beyond the vaquita habitat area.
Barlow noted that gillnets are so long and so frequently used in the upper gulf that they sometimes cover the water surface, impeding the use of "small trawl" shrimping boats that, because of their noisy motors and smaller nets, seldom catch vaquitas.
Barlow said "I do believe the species can be saved, but only with emergency action."
Capturing vaquitas to breed them in captivity isn't an option, the report concluded, because it would not be feasible to capture or hold a sufficient number of them to develop a captive breeding program. Furthermore, with so few vaquitas spread over such a wide area, chasing down and catching them would risk killing off the few remaining individuals.
"They would probably die in the attempt" to capture them, Vidal said.