“I take the good old-fashioned ground that the whale is a fish,” Ishmael says confidently in Melville’s Moby Dick. Old-fashioned indeed—whales are mammals, not fish. Thankfully, our scientific understanding of whales has come a long way since 1851, and much of that knowledge is collected in Whales, Dolphins and Porpoises, a sperm whale-sized compendium of all things cetacean, out this weekend.

But scientists know practically nothing about beaked whales, a family that makes up about a quarter of all cetacean species. Mostly, that’s because beaked whales live in the places humans can’t easily reach—they evolved to spend long periods of time foraging in the deep ocean, only surfacing for minutes at a time. Up until recently, the only way scientists could study beaked whales was if one washed up dead on a beach. So marine biologists have a conundrum: How do they study these elusive, remote animals without killing them?

“With great patience,” says marine biologist Erin Falcone. She and her team at the Cascadia Research Collective in Olympia, Washington have spent the past decade developing a suite of hardy tech to spy on these animals.

Their system is organized around the 90 seconds or so a beaked whale spends at the surface. “They come up, they take a few breaths, they’re done, they’re gone,” Falcone says. So the Cascadia lab partners with a naval submarine training range off the coast of San Diego, which has a field of underwater microphones. When their naval partners hear the telltale clicks of a foraging beaked whale, they radio Falcone and her team, who head out and wait for the whale to surface. “We spend a great deal of time staring out at the empty ocean, hoping we’re close enough to go over and place tags on them,” she says. (It helps that they have a fast, nimble boat.)

If they’re lucky, a whale will surface in prime position for them to hit it with a tag, a $5,000 piece of technology no bigger than a golf ball. Designed specifically for deep-diving Cuvier’s beaked whales, the tag contains a depth sensor, a satellite transmitter, a saltwater switch, and a long-lived battery. It also has two titanium darts that cling to the whale’s fin during deep dives, but eventually fall out so the whale isn’t wounded forever. Each tag is tested at a land range for ballistics, since they need to fly true when scientists shoot them out of an air rifle on the choppy seas.

Erin A. Falcone/Cascadia Research Collective

Once the tag is in, the scientists wait for the data to come through. For the next few months, the tag reports the animal's goings-on back to the scientists. Every time the whale surfaces, the tag dumps data—information about location, trajectory, and depth of each dive—to a network of satellites or the lab’s shoreside data station.

This process yields great fine-grained data, but it’s also complicated and full of risks. So Simone Baumann-Pickering, a biologist at Scripps Institution of Oceanography, uses a different tactic: tracking and analyzing the high-pitched clicks the whales make when they hunt. She and her team drop large cubic meter-sized instruments to record the sounds on the ocean floor, everything from the low-frequency hum of baleen whales to passing ships to the ambient rush of water. Then, after the data come back, she reverse-engineers the soundtrack and picks out the whales’ high-pitched echolocation.

From that data, Baumann-Pickering can deduce how many animals there are, how well the population is doing, how water temperature affects numbers, and how people-generated noise impacts the whales’ behavior. “It’s a lot of ecological questions you otherwise wouldn’t be able to detect,” she says.

And that’s important, because Navy sonar can strand and kill beaked whales. That’s ironically what attracted biologists’ attention to the animals in the first place, but ultimately, all this roundabout data-collecting is to help keep the whales swimming in their remote, deep-ocean homes.