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Wednesday, April 24, 2024

Want to Save the Whales? Eavesdrop on Their Calls

Things have been rough lately—the pandemic, unprecedented wildfires, General Governmental Awfulness—and all the while, a less conspicuous plague has been menacing whales, particularly off the California coast: ship strikes. In 2018, according to the National Oceanic and Atmospheric Administration, there were 14 confirmed cases of ships hitting whales in the region, 10 of which were fatalities. In 2019 there were 13 strikes and 11 fatalities. Put together, they were the worst two years for California ship strikes ever. And that’s only what’s recorded. Scientists reckon they’re only finding between 5 and 17 percent of the dead whales. The vast majority sink or wash out to sea, so the actual toll is probably much higher.

Today, a multidisciplinary team of scientists is launching a project to help give whales safer passage along the California coast, and they hope to spread the system around the world. “We see whales either wash up onto beaches with signs of broken bones and bruising, or we see them actually come into port on the bow of the ship,” says Morgan Visalli, project scientist at UC Santa Barbara’s Benioff Ocean Initiative, who helped develop the system, called Whale Safe. “Often the captain and crew don't even know that this has occurred.”

With Whale Safe, Visalli and her colleagues are deploying a network that combines three components to alert ships of humpback, blue, and fin whales in the area: oceanographic models that predict where individuals might show up, human observers on whale-watching boats spotting the animals as they surface, and a clever buoy that spies on the animals’ calls. It’s all collated into a website and email alert system for cargo companies that move ships through the ports at Los Angeles and Long Beach so operators can warn their vessels to slow down if whales are in the shipping lanes.

Think of it like establishing a school traffic zone, of sorts. “In a similar fashion, slowing down around the whales gives them more time to react and gives the ships a little more opportunity to avoid running into the whales,” says Douglas McCauley, director of the Benioff Ocean Initiative, who helped develop Whale Safe. “So it's a bit like that same concept for oceans—with really, really big school kids.”

These school kids are much harder to spot, though, which is where that buoy comes in. Floating near the shipping lanes of the Santa Barbara Channel, the buoy is attached to an underwater microphone, known as a hydrophone, positioned 200 meters deep on the seafloor. When the hydrophone hears a whale song, it sends that data up a line to the buoy, which transmits the signal to scientists on land.

But that’s not as easy as it sounds—literally—because it’s hard to anchor a floating microphone without creating background noise. “Moorings are typically made from chain, so they clank a lot,” says Mark Baumgartner, whale ecologist and senior scientist at the Woods Hole Oceanographic Institution, who helped develop the technology. “And that's not really good when you're trying to hear animals that are many miles away making sounds.” So Baumgartner and his colleagues made the first 100 feet of mooring out of a rubbery “stretch hose.” When the buoy bobs on waves and tugs on the mooring, that stretchy bit coming off the instrument stays silent, allowing the hydrophone to listen for whales undisturbed.

Transmitting the data is another hurdle: Audio files take up a lot of space, and the connection that sends them from the buoy to a satellite to Baumgartner’s lab is maddeningly slow. Like, worse than 1X, the primitive cell phone technology, and way worse than LTE or 3G. “You have to squeeze them through this tiny, tiny, slow, really expensive data pipe to get home,” says Baumgartner. “And so one way around that problem is to not send the audio home, but to send representations of the audio home.”

Think about sheet music: The notes and other symbols are a distillation of the extremely complex sounds of the orchestra, but musicians can still read and play them. “It faithfully captures sound, if you know what you're looking at, but it doesn't actually contain the sound,” Baumgartner says. “This instrument does exactly that—it almost deconstructs the sounds into musical notes.”

They call these representations “pitch tracks,” which document the changes in the sounds the hydrophone is detecting, creating a sort of sheet music for whale song. A small computer in the instrument contains a database of whale calls, so it can take an educated guess at which species it might be hearing. But the instrument doesn’t make the final interpretation. “We have an analyst who, like the musician, can look at those pitch tracks and interpret what sounds are there,” Baumgartner says. And the analyst is damn good at it, nailing just about 100 percent of the species identifications during tests as the team evaluated their instrument in the real world.

But why not just fully automate the system and let the instrument do all the identifying? Because it’ll tally a lot of false positives by counting other noises as whale calls, Baumgartner says, and that’s unacceptable given what’s at stake: voluntary buy-in from the shipping industry. If you’ve got a lot of false alarms, and ships have to keep slowing for whales that aren’t there, you’re not doing the animals or the boat captains any service—crying whale instead of crying wolf.

“When the stakes are high, you want to be really careful,” Baumgartner says. “Like the systems, for instance, that I imagine the Air Force has for detecting incoming nuclear bombs. You probably don't want to have a fully automated system, because if they did it wrong, there are big consequences. And so if you're using a system to regulate interactions between an industry and an endangered species, automation is great, but I think accuracy might be more important than expediency or cost.”

So in addition to working with a dedicated whale listener, the Whale Safe team also relies on trained observers on whale watch and tourism boats off the coast of Southern California, who detect cetaceans the old-fashioned way and log them in a mobile app. The Whale Safe oceanographic modeling uses sea temperatures and other data to predict where whales’ favorite food, tiny crustaceans known as krill, are likely to show up. This is another data point that helps them tell cargo ships which spots whales may frequent. “So the acoustic data, the sightings, and the model data are integrated into the Whale Safe platform and then communicated out to the shipping industry and to government to help drive better decision­making to try to reduce the risk of ship strikes,” says Visalli, of the Benioff Ocean Initiative.

Until now, whale protection initiatives in Southern California have been limited to voluntary speed restrictions put in place by NOAA—10 knots or less, which is about 11.5 miles per hour—usually from May to November, when whales are most abundant off the coast. “It's voluntary, so there's not great cooperation with it,” says Visalli. “It's been slowly increasing over the years, but not everybody is following the speed limit, that's for sure.”

Why not just shift the shipping lanes to avoid the path that whales frequently travel, which runs between the shore and the nearby Channel Islands? Theoretically, the lanes could be moved to the backside of the islands. “But that region is also a missile testing range for the Department of Defense,” says Visalli. “They really do not like when ships go back there, and they tend to be able to trump other proposals for whale protection.”

The best option is to just to get ships to slow down. “The biggest thing is just speed,” says Dan Hubbell, shipping emissions campaign manager at the Ocean Conservancy, who wasn’t involved in developing Whale Safe. “If this actually can provide the kind of data necessary to help ship owners slow down below 10 knots, they'll drastically reduce the likelihood of a fatal strike on a whale.” And the planet gets a bonus: “Reducing your speed by about 10 percent reduces your [greenhouse gas] emissions by about 13 percent when every other factor is taken in,” Hubbell adds.

Slowing down has grown more critical because whales are acclimating—and not in a good way—to all the noise we're introducing into the oceans, from giant ships or otherwise. Think about the constant din of a city: Over time, people grow numb to it, and they jump less at car horns and construction noise. A whale constantly bombarded with the sound of ship engines may also be tuning the commotion out, making it more vulnerable to a strike. "It'd be like if there was a jackhammer or something going and you tuned it out, but then that jackhammer went right through you," says Tim Markowitz, cetacean field research coordinator for the Marine Mammal Center in Northern California.

The utility of Whale Safe, Markowitz adds, is that it can nicely complement traditional ways of detecting whales, like visually scanning the ocean's surface. The Marine Mammal Center staff is hoping to deploy a similar system in the San Francisco Bay, where whales face the same conundrum they do down south: The environment is simply too constrained. Ships are constantly moving in and out of the bay, squeezing under the Golden Gate while whales do the same. "Because the vessels have to go through a pretty narrow area, there's kind of limited maneuverability," says Markowitz. "It's a concern because ship strikes can happen." Last year, five gray whales were struck and killed in the bay.

“This doesn't solve the issue of ship strikes, by any means, globally,” says McCauley. But they hope that much of the tech the team developed is immediately exportable to whale guardians around the world, allowing them to spy on the cetaceans’ calls like never before. “For example,” McCauley says of the buoy’s stretchable hydrophone cable, “this silent deep-water mooring that isn't singing like a 200-meter guitar string anymore.”

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