What did the ocean sound like before humans?

Imagine it’s the early 1900s and you are a giant blue whale resting in the warm waters of the Santa Barbara Channel, off the coast of Southern California. what are you listening? The songs of fellow whales, babbling streams, the occasional foghorn, perhaps.

Fast forward to 2024, and the tranquil environment you once called home now feels very different as large cargo ships sail overhead, ripping the waters with powerful propellers, as they navigate two of the world’s most Arrive at busy ports.

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While few land residents have thought much about this change in ambient marine noise, new research has for the first time modeled how the Industrial Revolution and the advent of commercial shipping have increased the volume in Los Angeles waters.

According to a study recently published in the journal Nature, the calm environment of the Santa Barbara Channel is now about 30 times noisier than before. Marine Pollution Bulletin,

According to the study’s lead author Vanessa Zobel, noise can have a profound impact on whales and other creatures that pass through the channel or call it home, many of which use sound and echolocation as their primary way of sensing the world around them. But trust. and postdoctoral researcher at the Scripps Institution of Oceanography.

“Sound is everything to marine creatures – especially because about 90% of the ocean is dark during the day, and 100% at night,” Zobel said.

“It’s the only sense that a lot of sea creatures have, and noise pollution — especially for the L.A. area — is dominated by commercial shipping,” he said. “When you’re spreading a lot of noise into this area, it’s masking the feeling that these animals need to survive.”

A Garibaldi floats in the shallow waters of Catalina Island in January 2016.

(Alan J. Schaben/Los Angeles Times)

The researchers chose to focus on the Santa Barbara Channel in part because it contains 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 had overwhelmed the ports of Los Angeles and Long Beach. Had changed. The two busiest ports in the Western Hemisphere,

They found that before the introduction of vessel cargo containerization in the 1950s, the baseline volume in the channel was about 60 to 80 decibels – relatively low compared to the cacophonous sound heard today. Now the noise level has increased by 15 decibels.

“It’s like having a conversation in your kitchen (versus) having a conversation on the side of the freeway with a bunch of semi-trucks,” Zobel said.

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

Sean Hastings, a policy, information and management officer at the Channel Islands Marine Sanctuary, called the study’s findings “very significant” and said they urgently need efforts to slow ship speeds, adjust shipping lanes and other efforts to reduce ocean noise. Meet the need and protect the wildlife.

“These animals have evolved in the ocean for millions of years, but only in the last 150 years – the era of the Industrial Revolution – have things changed dramatically at the speed and scale with which they had not evolved,” he said.

Hastings said noise pollution can reduce an animal’s ability to detect and interpret acoustic signals, including sounds used for mating, feeding, travel and migration. This may also increase their stress.

A lone boat sailing at sunset off Catalina Island in August 2020.

(Alan J. Schaben/Los Angeles Times)

The findings are particularly important in the Santa Barbara Channel, which is recognized internationally biosphere Reservea designated Whale Heritage Area, and is one of the most important whale migration routes in the United States. Blue whales and humpback whales typically come into the channel around May 1 and stay until December to feed, breed and give birth to their babies, Hastings said, “and so this is a really important time frame when they It happens here.”

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

He said, “I know that when I’m snorkeling or diving and a small boat passes overhead, it gets dizzy because the sound feels like it’s everywhere.”

According to Zobel, the Channel Islands may also act as a “shield” that blocks sound within the Santa Barbara Channel, enabling noise to be louder than in deeper, more open ocean waters. This is one of several factors the researchers had to consider in their acoustic modeling, along with wind speed, temperature and time of year, which can affect the propagation of sound through the ocean.

And although container ships produce the most noise underwater, smaller vessels including fishing boats and pleasure craft also contribute to sound volume, which can affect not only whales but also dolphins, spiny lobsters and some fish. Is.

“This is an area with a lot of human and wildlife interaction,” Zobel said.

Marine noise is also not limited to commerce. In recent years, the US Navy has come under criticism for testing and training activities involving high-intensity mid-frequency sonar in ocean waters, with the Navy admitting in 2002 that the noise was killed at least six whales Near Bahamas.

In 2015, a federal court approved settlement 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 marine life.

“There is no easy solution to separating ships and whales and national defense training,” Hastings said. “So… when whales are present, we are asking vessels to slow down. And when and where we can, we are pushing lanes into deeper water, we are expanding the areas that should be avoided. You look at this multi-dimensional approach.”

That approach involves a program called Protecting the blue whale and the blue sky, Operated by a coalition of non-profit organizations, government agencies and industry groups that require shipping companies to voluntarily reduce their speeds to 10 knots or less in the Santa Barbara Channel as well as other parts of the Southern California coast and San Francisco. Recognizes and rewards. and Monterey Bay area.

The group says slower speeds not only help limit noise but also reduce greenhouse gas emissions and prevent more ships from colliding with whales and other animals.

2023 season of the program It involved the participation of 33 global shipping companies who collectively traveled approximately 375,000 nautical miles at speeds of 10 knots or slower within speed reduction zones.

The organization reported that the top performing vessels had sound levels 5.4 decibels lower per transit compared to 2016 baseline source levels, and that “with reduced noise pollution, whales can more easily communicate.”

A new law was introduced this year, Assembly Bill 2298Seeks to expand the Protecting Blue Whales and Blue Skies program to the entire California coast “to reduce air pollution, the risk of fatal vessel strikes on whales, and harmful underwater acoustic impacts.”

The shipping industry is also beginning to explore new, green designs, such as electric engines and hydrogen hybrid propulsion systems, which can help reduce noise and provide other benefits, including improved air quality.

While it may take some time for those changes to be able to meet the needs of the largest cargo ships, Hastings said consumers can ask themselves whether they are willing to trade slower shipping speeds for better marine and marine wildlife conditions. Are willing to.

“Can they wait an extra few hours for their favorite shoes or 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 although the study could help inspire additional changes in the future, Zobel said it also plays an important role in establishing a clearer understanding of the past.

“Now we have a goal to go back and we know what the natural sound landscape is in which the animals there have evolved to thrive,” he said. “I don’t think we’ll ever get back to that, but at least we have something to try for.”