The US Navy plans to deploy its squadron of highly trained, bomb-locating bottlenose dolphins this spring. But the dolphins won’t be using their sonar for their usual missions of hunting down underwater mines or warding off enemy swimmers. Instead, the dolphins will be searching out their tiny, highly endangered relatives called vaquitas in an effort to conserve the last of these rapidly disappearing porpoises.

There are less than 30 vaquitas left in the world

According to a new report, there are less than 30 vaquitas left in the world. That means that half of the population has disappeared since the last survey in 2015 — and this alarming drop means they soon could be gone forever.

The vaquitas live in the slice of ocean called the Gulf of California that splits the Sonoran Desert in Mexico. Over the last two decades, they’ve been driven to near extinction — drowned by the gillnets that poachers use to catch a giant fish called the totoaba. The totoaba is also critically endangered and prized in China for its swim bladder used in traditional Chinese medicine, according to Ben Goldfarb for Environment 360.

The US and Mexican Navies as well as scientists in both countries have partnered up to use the Navy’s bottlenose dolphins to locate vaquitas, the San Diego Union-Tribune reports. The plan is to capture a few vaquitas, and keep them safe until the region is free from illegal fishing.

“Despite heroic efforts to ban gillnets and to increase enforcement using the Navy, this illegal fishing for totoaba has continued and the recovery team felt that they needed to try something else — because at that rate [the vaquitas] will be gone in the next year or two,” says Barbara Taylor, a marine mammal geneticist with the National Oceanic and Atmospheric Administration and a vaquita conservationist. Taylor has been involved in acoustical surveys that listen in on the Gulf of California to try and hear how many vaquitas are talking. She’s hearing fewer and fewer of them.

For the past year, experts from the US and Mexico have been collaborating with the Navy to figure out how to save the last of the vaquitas, said Lorenzo Rojas-Bracho, chair of the International Committee for the Recovery of the Vaquita, in a statement emailed to The Verge. More details will be released in the coming weeks, a spokesperson with the Ministry of the Environment and Natural Resources of Mexico, added in an email.

“If we can’t get this situation under control with illegal totoaba fishing, we’ll at least have some vaquitas left.”

The US Navy has been working with marine mammals since the 1950s, and these days it focuses on training dolphins and sea lions for underwater missions. Both can be taught to find and mark underwater objects like mines or research and military equipment that needs to be retrieved. They also can be trained to be the underwater equivalent of guard dogs, protecting naval assets like piers and ships from attacks by swimmers. These highly trained marine mammals have been deployed across the world.

Now, the dolphin team will turn its particular set of skills toward protecting the vaquita. Right now, the plans are to use the bottlenose dolphins to locate and capture a few vaquitas, and transport them to a safe location. If the captured vaquitas were then to breed, that would be ideal — but Taylor’s not raising her hopes. The team just hopes to keep a few vaquitas alive. Eventually the goal is to return the tiny porpoises to the Gulf of California.

“There are a million puzzle pieces that have to come together.”

“We’re targeting late spring but there are a million puzzle pieces that have to come together and we’re flat out working as hard as we can,” Taylor says. One of the puzzle pieces included a test run in the San Francisco Bay, according to the San Diego Union-Tribune. The Navy’s bottlenose dolphins successfully located San Francisco’s harbor porpoises, the Tribune reports.

Not everyone supports an attempt to capture vaquitas — fearing it could endanger the few that remain. “The risk of killing a vaquita while catching them is very high,” Omar Vidal, director general of the World Wildlife Fund Mexico, told Ben Goldfarb writing for Science in July. With that potential for risk, it’s a difficult decision to endanger the few still alive. But as their population continues its alarmingly precipitous decline, it’s difficult to imagine that there are many other options.

Taylor agrees that the most important thing is to make sure that the vaquitas remaining in the wild can survive. “The first and most important thing is to continue the gillnet ban and to increase enforcement because most vaquitas are still going to be in the wild,” she says. “The new part is trying to take at least some of the vaquitas into temporary sanctuary so if we can’t get this situation under control with illegal totoaba fishing, we’ll at least have some vaquitas left.”

Update 1:59PM ET, 2/2: Updated to include new vaquita population counts published today.