Mexico's Vaquita Refuge Leaves Known Habitat Exposed

Mexico's vaquita refuge covers only a small portion of the porpoise's known range, while fishermen continue setting gillnets along the exclusion zone's outer edge. The latest survey, in 2024, estimated just six to eight vaquitas. Acoustic detectors suggest the animals may range more widely, but the estimate was still no more than nine to 11.

Protection With Gaps

The Mexican government has prohibited commercial fishing in a vaquita refuge and placed cement blocks fitted with metal hooks throughout the exclusion zone to capture abandoned and illegal gillnets. Conservation groups, especially Sea Shepherd Conservation Society, monitor the area, with support from the Mexican Navy. Their work has reduced illegal fishing activity inside the protected area, but its boundaries leave out a northwestern zone where vaquitas may be active.

The 225-square-kilometer Zero Tolerance Area, established in 2020, faces pressure from calls to resume unrestricted fishing in areas where vaquitas are said no longer to be found. Meanwhile, gillnets remain along the exclusion zone's outer edge. The protections operate within a map that leaves part of the animals' known range exposed.

The netting is set to catch totoaba, a large fish endemic to the Gulf of California, not vaquitas. But vertical panels suspended from lines also trap the porpoises, and predators drawn to trapped fish can become entangled too. Totoaba bladders are used in traditional Chinese medicine and luxury cuisine, and much of the catch goes to the Hong Kong market. The target is one species; the nets ensnare another, already among the world's most endangered.

Numbers Falling, Nets Still Set

Researchers don't know how many vaquitas once lived in the gulf. Academic studies suggest about 5,000, but a comprehensive survey in 1997 estimated 567. The population estimate fell to 150 by 2007 and fewer than 19 by 2018. The latest survey's six to eight animals may be an underestimate because surveys have focused on a small area where vaquitas are known to occur. Acoustic detectors point to a wider range, though they still suggest no more than nine to 11 animals.

In 2007, scientists published “Saving the Vaquita: Immediate Action, Not More Data” in Conservation Biology after the Yangtze River dolphin, another endangered cetacean, was confirmed extinct. A decade later, the international coalition VaquitaCPR began a $5 million effort to save vaquitas by keeping them in floating sea pens if nets couldn't be removed. The team captured two. A mature female suffered acute shock and died within hours in a pen; a young calf showed extreme stress and was released. The attempt ended with the loss of both animals as the population continued to fall.

A Narrow Opening

Scientists are still studying vaquita reproduction. A female called Frida, recognizable by a bent dorsal fin, was seen with a calf in 2023 and a newborn in 2024. In 2025, she was seen with a calf that appeared about a year old and physical signs that she might have been pregnant again. Researchers have raised questions about the previous belief that females give birth only every two years. A change in breeding patterns could be linked to reduced competition for food and might offer hope for the species' future.

Historical DNA from porpoises caught in nets suggests the species has been isolated so long that it may have adapted to the risks of inbreeding. But the article notes that conservation measures introduced when numbers were in the low hundreds might have offered more optimism. Recovery would require years of protection and monitoring, while gillnets, the limits of the refuge and pressure to reopen areas for fishing remain part of the present picture.