Over the past few years, the vaquita—a small porpoise that lives exclusively in the shallow waters of Mexico’s Gulf of California—has been careening towards extinction. By 2016, scientists had concluded that vaquita numbers had dropped to 30, down from around 200 in 2012. Despite efforts to protect the animals, the vaquita population has continued to dwindle; according to a new study published in Royal Society Open Science, there are 19 vaquitas “at most” left in the wild.

It is difficult and expensive to conduct visual surveys of vaquitas, the rarest of all marine mammals. But scientists have been able to keep track of the animals using 46 acoustic sampling locations that measure echolocation clicks; vaquitas are chatty creatures, producing a “nearly continuous” stream of vocalizations, according to the study authors.

The detectors were installed in 2011, and ever since, experts have been monitoring the vaquitas’ alarming decline. The new report looked at acoustic data from 2017 and 2018, also taking into account a population estimate from 2015 and visual observations. As of last summer, the researchers concluded, vaquitas likely numbered fewer than 19. This represents a 98.6 percent decline since monitoring began eight years ago, and the reality of the situation may in fact be even more dire.

“Based on the uncertainty inherent in the models, the number [of vaquitas] could be as few as six,” Len Thomas, an ecological statistician at the University of St Andrews and study co-author, tells Anna Ploszajski of the Guardian.

The primary threat to vaquita survival is illegal fishing, specifically the use of gillnets, a wall of netting that hangs in the water. Fishermen in Mexico use these nets with the goal of trapping totoaba fish, which, like vaquitas, have been deemed “critically endangered” by the IUCN. Totoaba swim bladders—gas-filled sacs that help fish stay buoyant—are highly prized in China for their use in traditional medicine. Justin Rohrlich of Quartz reported last month that the bladders can sell for between $20,000 and $80,000 per kilogram.

Mexico banned totoaba fishing in 1975, according to Rohrlich, but poachers continue to ensnare them—and vaquitas often get tangled up in gillnets intended for the large fish. The Mexican government has taken a number of emergency measures to protect the marine mammals. In 2004, for instance, it established a Vaquita Refuge in the northern Gulf of California and launched a monetary compensation plan for fishermen who worked in the area. In 2015, officials implemented a two-year ban on gillnets in the vaquitas’ range.

And yet, vaquitas are still dying in gillnets. According to the new study, ten dead vaquita have been found between 2016 and 2019; experts were able to determine the cause of death for eight of the animals, all of which had died due to entanglement in gillnets.

Though the outlook for vaquitas is currently grim, there is some good news. As the study authors note, a recent survey found that the surviving vaquitas are perfectly healthy, and also documented the presence of two calves—meaning that the species should be able to rebound if the bycatch threat is removed. To that effect, the researchers recommend guarding vaquitas during the totoaba spawning season, which spans from December to May. They also stress that it is vital to actively remove gillnets from vaquita territory—something that the conservation group Sea Shepherd, in partnership with the Mexican government, has been doing.

“In addition,” the study authors write, “providing access, training and support to develop legal alternatives for fishers requires a longer time frame but is critical for increasing compliance with the gillnet ban in local communities.”

With sufficient effort, in other words, it is possible to bring the vaquita back from the brink of extinction. But time is running out for the speice.

“Every day wasted is making a difference. The key thing is that we need action now,” Thomas tells Madeleine Gregory of Vice. “There are only days to do this.”