What did the ocean look like before humans?

Imagine it’s the early 1900s and you’re a giant blue whale basking in the warm waters of the Santa Barbara Channel, just off the coast of Southern California. What do you hear? Whale songs, murmuring currents, an occasional foghorn, perhaps.

Fast forward to 2024, and the calm environment you once considered home now seems very different as massive cargo ships circle overhead, cutting through the water with powerful propellers as they converge on two of the busiest ports in the world.

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Although few land-dwellers 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 increased the volume of waters off the coast of Los Angeles.

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

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

“Sound is essential for marine organisms,” ZoBell said, especially because about 90% of the ocean is dark during the day and 100% at night.

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

A Garibaldi swims in the shallow waters 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 endangered Northeast Pacific blue whale. of disappearance at the federal level.

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

They found that before the introduction of containerization of goods by ship in the 1950s, the baseline volume in the canal was around 60 to 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 (rather than) having a conversation on the side of a highway with a bunch of tractor-trailers,” ZoBell said.

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

Sean Hastings, head of policy, information and management at the Channel Islands Marine Sanctuary, called the study findings “very important” and said they highlight the urgent need to slow down ship speeds, adjust shipping lanes and other efforts to mitigate ocean noise and protect wildlife.

“These animals have evolved over millions of years in an ocean that has only changed in the last 150 years – around the time of the Industrial Revolution – at a rate and scale with which they have never not evolved,” 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 their stress.

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

(Allen J. Schaben / Los Angeles Times)

The findings are particularly significant 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 and humpback whales typically arrive in the channel around May 1 and stay until December to feed, breed and give birth to their young, “so it’s a very important time when they’re here.” , Hastings said.

Although divers generally avoid swimming where ships and whales converge, Hastings said it’s not difficult for humans to imagine what the extra noise is like.

“I know when I’m snorkeling or diving and a small boat passes overhead, it’s dizzying because the sound feels like it’s everywhere,” a- he declared.

The Channel Islands may also act as a “shield” that constricts sound in the Santa Barbara Channel, allowing noise to propagate further than in deeper, more open ocean waters, according to ZoBell. It’s one of several factors the researchers had to take into account in their acoustic modeling, alongside wind speed, temperature and time of year, all of which can affect how the its spread in the ocean.

And although container ships generate the most underwater noise, small vessels – notably fishing boats and pleasure boats – also contribute to the volume, which can affect not only whales but also dolphins, lobsters and certain fish.

“It’s an area with a lot of human and wildlife interactions,” ZoBell said.

Ocean noise isn’t limited to commerce, either. In recent years, the U.S. Navy has been criticized for its testing and training activities involving high-intensity mid-frequency sonar in ocean waters, with the Navy admitting in 2002 that the noise killed at least six whales near the Bahamas.

In 2015, a federal court approved the settlement of 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 have been proven once again to harm marine life.

“There is no simple solution to separating ships from whales and national defense training,” Hastings said. “So… when the whales are present, we ask the ships to slow down. And when and where we can, we push the routes into deeper waters, we expand the areas to avoid. You see this multi-pronged approach.

This approach includes a program called Protecting Blue Whales and Blue Skies, run by a coalition of nonprofit organizations, government agencies and industry groups, which recognizes and rewards shipping companies for voluntarily reducing their speed to 10 knots or less in the Santa Barbara Channel, as well as other parts of the southern California coast and the San Francisco and Monterey Bay area.

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

The program’s 2023 season included the participation of 33 global shipping companies, which collectively sailed approximately 375,000 nautical miles at 10 knots or less in speed reduction zones.

The best-performing ships had sound levels 5.4 decibels lower per transit than 2016 baseline levels, the organization reported, adding that “with a reduction in noise pollution, whales can likely communicate more easily “.

New legislation introduced this year, Assembly Bill 2298, aims to expand the Blue Whale and Blue Sky Protection Program to California’s entire coast “to reduce air pollution, the risk of fatal collision with whales and harmful underwater acoustic impacts.”

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

Although it may be some time before these 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 conditions for the ocean and marine wildlife.

“Can they wait a few extra hours for their 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 more sustainably. »

And while the study may help inspire additional changes in the future, ZoBell said it also plays an important role in establishing a clearer idea 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,” she said. “I don’t think we’ll get back to that, but at least we have something to aim for.”