During a few weeks each year or so, an international team of scientists spends long days at sea searching for the most endangered marine mammal on Earth: the vaquita porpoise. The species is teetering on the edge of extinction, with recent surveys estimating around 10 individuals in the area where they’ve been considered most likely to live.
Results from this year’s survey, issued on Tuesday, were disappointing: Researchers estimate they saw six to eight individual vaquitas there, the lowest result ever recorded.
Still, the scientific team and the Mexican government cautioned that the population had not necessarily declined, emphasizing that more vaquitas may exist outside the search area. Since at least 2019, the visual surveys have focused on one zone where acoustic monitoring and other research has suggested the remaining animals congregate.
“It’s worrisome,” said Barbara Taylor, a longtime vaquita researcher who led the survey. “We just need to go out and find out whether the vaquitas have moved someplace else and adapt the management accordingly.”
The world’s smallest porpoise, vaquitas have rounded faces with panda-like markings around their eyes and lips that seem to pull up into a Mona Lisa smile. Their name in Spanish, vaquita marina, means little sea cow.
The individuals observed during the survey appeared in good health. One group of four included a yearling.
Vaquitas live only in the Gulf of California, the body of water that separates Baja California from the Mexican mainland. Their numbers have been decimated by gill nets, a type of fishing gear that uses huge, drifting nets to trap shrimp and fish. Vaquitas (and other marine mammals and sea turtles) can get entangled in the nets and drown.
Illegal targeting of a fish called the totoaba, itself endangered, has pushed vaquitas to the brink. The totoaba’s swim bladder sells for high prices in East Asia, attracting organized crime and fueling violent confrontations. Gill nets for totoaba are especially lethal to vaquitas.
Last year’s survey had brought brighter news: Scientists not only spotted a steady number of vaquitas, but they also documented a drastic reduction in the number of gill nets in the search area, which overlaps with the most highly protected zone for vaquitas, known as the Zero Tolerance Area. Months earlier, the Mexican Navy had dropped 193 concrete blocks with giant hooks designed to entangle gill nets, apparently deterring fishers. In August 2023, more than 200 additional blocks were approved for the same zone and nearby.
The issue, researchers say, is that vaquitas may not be staying there.
Ocean conditions can change because of natural forces like El Niño, a cyclical weather pattern, and human-driven ones like global warming. Vaquitas eat mainly small fish; if their food moves, they will move, said Lorenzo Rojas-Bracho, a biologist who participated in the survey and who spent decades studying vaquitas at Mexican government agencies before moving to the National Marine Mammal Foundation, a nonprofit group.
The blocks with hooks “are buying time, but they will not save the vaquita,” Dr. Rojas-Bracho said.
Instead, he and other experts say, the problem needs to be addressed at its root by transitioning fishers to alternative gear so they can make a living without accidentally drowning vaquitas. Only a tiny fraction of fishers in the area are doing so now.
A recent report by the scientific committee of the International Whaling Commission expressed “deep concern and disappointment at the Government of Mexico’s lack of progress in carrying out a rigorous and transparent assessment of alternative fishing gear.”
Pablo Arenas Fuentes, general director of the Mexican Institute for Research in Sustainable Fisheries and Aquaculture, a government institution, called that criticism “completely false.” He said the Mexican government has helped to develop at least two kinds of alternative gear for shrimp, the main catch.
“There’s no doubt that the fishermen have available gear,” Dr. Arenas said. “What we as a government have not done is to persuade them to implement widely this gear.”
Local fishermen say the gear doesn’t perform well enough in the conditions of the Upper Gulf.
Mexico faces potential consequences related to vaquitas, including through its trade agreement with the United States and Canada.
The Office of U.S. Trade Representative has been working with Mexico on a plan to protect vaquitas “but progress has been slow,” said Catherine White, a spokeswoman.
Vaquita researchers plan to expand acoustic monitoring this summer to better understand where the animals might be. Similar efforts have been largely thwarted because the equipment was vandalized, presumably by fishermen who resented vaquita-related restrictions. Now the scientists are trying a recording device that stays below the surface, out of sight, until it’s ready to be collected. They will also gather environmental DNA.
A spokeswoman for Mexico’s National Commission of Protected Natural Areas said the results of that research would inform proposals of new fishing and no-fishing zones, and that a training for fishers on alternative gear was planned for August and September.