What did the ocean sound like before humans?

Imagine it's the early 20th century and you're a giant blue whale sunbathing in the warm waters of the Santa Barbara Channel, off the coast of Southern California. What do you hear? Songs of whales, murmurs of currents, the occasional foghorn, perhaps.

Fast forward to 2024, and the tranquil environment you once called home now sounds very different as massive cargo ships spin overhead, cutting through the water with powerful propellers as they converge on two of the world's busiest ports.

While few people on Earth have given much thought to this shift in ambient marine noise, new research has modeled, for the first time, how the Industrial Revolution and the advent of commercial shipping have increased the volume in Los Angeles waters. .

The once quiet environment of the Santa Barbara Channel is now about 30 times noisier than it was before, according to a study recently published in the journal Marine Pollution Bulletin.

The noise can have a profound effect on the whales and other creatures that pass through the channel or call it home, many of which rely on sound and echolocation as their primary way of perceiving the world around them, according to author Vanessa ZoBell. main of the study. and postdoctoral researcher at the Scripps Institution of Oceanography.

“Sound is everything to marine organisms,” ZoBell said, particularly because about 90% of the ocean is completely dark during the day and 100% at night.

“It's the only sense many marine organisms have, and noise pollution, specifically in the Los Angeles region, is dominated by commercial shipping,” he said. “When you radiate a lot of noise into the region, it kind of masks the feeling that these animals need to survive.”

A Garibaldi swims in shallow water off Catalina Island in January 2016.

(Allen J. Schaben/Los Angeles Times)

Researchers chose to focus on the Santa Barbara Channel in part because it encompasses the Channel Islands National Marine Sanctuary and a feeding ground for the federally endangered Northeast Pacific blue whale.

The study modeled the soundscape of the channel in August 2017, when both whales and heavy ship traffic were present, and compared it to the same area decades earlier, before the influx of commercial shipping transformed Los Ports. Angeles and Long Beach are the two busiest ports. in the Western Hemisphere.

They found that before the introduction of ship cargo containerization in the 1950s, the baseline volume in the channel was between 60 and 80 decibels, a relatively low hum compared to the cacophony heard today. Now, noise levels are up to 15 decibels higher.

“It's like having a conversation in your kitchen. [versus] having a conversation on the side of a highway with a group of trucks,” ZoBell said.

The problem may worsen in the coming years, the study says, as global containerized trade is expected to continue to rise due to growing consumer demand and expanding global markets. The volume of that trade more than tripled between 1990 and 2021, according to the United Nations Conference on Trade and Development.

Sean Hastings, policy, information and management officer at the Channel Islands Marine Sanctuary, described the study's findings as “very significant” and said they highlight the urgent need to reduce ship speeds, adjust shipping routes and other efforts to mitigate ocean noise and protect wildlife.

“These animals have evolved for millions of years in an ocean that only in the last 150 years (the era of the Industrial Revolution) has changed dramatically at a pace and on a scale they had not evolved before,” he said.

Noise pollution can reduce an animal's ability to detect and interpret acoustic signals, including sounds used for mating, feeding, traveling and migrating, Hastings said. It can also increase your stress.

A lone sailboat sails into the sunset off Catalina Island in August 2020.

(Allen J. Schaben/Los Angeles Times)

The finds are especially important in the Santa Barbara Channel, which is an internationally recognized biosphere reserve, a designated Whale Heritage Area, and one of the most important whale migration routes in the United States. Blue whales and humpback whales typically arrive in the channel around May 1 and stay until December to feed, breed and give birth to their calves, “so this is a really important period of time when they're up here.” Hastings said.

Although divers typically avoid swimming where ships and whales converge, Hastings said it's not difficult for humans to imagine what the added noise feels like.

“I know that when I'm snorkeling or diving and a small boat passes overhead, I feel dizzy because the sound seems to be everywhere,” he said.

The Channel Islands can also act as a “shield” that restricts sound within the Santa Barbara Channel, allowing noise to rumble louder than in deeper, more open ocean waters, according to ZoBell. It's one of many factors the researchers had to consider in their acoustic modeling, along with wind speed, temperature and time of year, that can affect how sound propagates through the ocean.

And although container ships generate most of the underwater noise, smaller vessels (including fishing boats and pleasure boats) also contribute to the volume, which can affect not only whales but also dolphins, lobsters and some fishes.

“It's a region with a lot of human-wildlife interactions,” ZoBell said.

The noise of the ocean is not limited to commerce either. In recent years, the US Navy has been criticized for testing and training with high-intensity, medium-frequency sonar in ocean waters, with the Navy admitting in 2002 that the noise had killed at least six whales near the Bahamas.

In 2015, a federal court approved settlements in two cases brought by environmental groups against the Navy and the National Marine Fisheries Service for deploying sonar tests off the coasts of Hawaii and Southern California, which were again found to harm life. Marine.

“There is no easy solution to separating ships from whales and national defense training,” Hastings said. “So… when whales are present, we ask the boats to slow down. And when and where we can, we are pushing the lanes into deeper water, we are widening the areas that should be avoided. “You see this multiple approach.”

That approach includes a program called Protecting Blue Whales and Blue Skies, led by a coalition of nonprofit organizations, government agencies and industry groups, that recognizes and rewards shipping companies for voluntarily reducing their speeds to 10 knots or except in the Santa Barbara Channel, as well as other parts of the Southern California coast and the San Francisco and Monterey Bay region.

The slower speed not only helps limit noise but also reduces greenhouse gas emissions and prevents more ships from colliding with whales and other animals, the group says.

The 2023 season of the program included the participation of 33 global shipping companies, which together traveled around 375,000 nautical miles at 10 knots or less within the speed reduction zones.

The best-performing ships had sound levels 5.4 decibels lower per transit compared to baseline levels from 2016 sources, the organization reported, adding that “with a reduction in noise pollution, whales will likely be able to communicate more easily.”

New legislation introduced this year, Assembly Bill 2298, seeks to expand the Blue Whale and Blue Skies Protection program along the entire California coast “to reduce air pollution, the risk of fatal collisions of whale boats and harmful underwater acoustic impacts.”

The shipping industry is also beginning to explore new, greener designs, such as electric motors and hydrogen hybrid propulsion systems, which could help reduce sound and provide other benefits, including better air quality.

Although it may be some time before those changes are able to meet the needs of larger cargo ships, Hastings said consumers may wonder if they are willing to trade slower shipping speeds for better marine and ocean living conditions.

“Can you wait a few more hours for your favorite shoe, computer or smartphone?” he said. “These are really special places and we can still get the products we love and we can do it in a more sustainable way.”

And while the study may help inspire additional changes in the future, ZoBell said it also plays an important role in establishing a clearer sense of the past.

“Now we have a goal to return to and we know what the natural soundscape is that animals have evolved to thrive in,” he said. “I don't think we'll go back to that, but at least we have something to fight for.”