Hakai Magazine

Coastal science and societies

a humpback whale surfaces with a container ship in the distance
Whales are more at risk of deadly collisions when ships are moving quickly. Photo by Enrique R. Aguirre Aves/Alamy Stock Photo

How California Clear Air Laws May Have Helped the Whales

Regulations aimed at reducing pollution pushed ships to slow down.

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by Julia Rosen

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Many species of whales feed, breed, and sing in California’s cool waters. They may seem impervious to terrestrial concerns, like improving air quality for coastal residents. But a new study suggests that clean air rules implemented in California led to dramatic changes in ship routes and speeds, some of which likely bode well for whales.

A team led by T. J. Moore, a research analyst at the US National Oceanic and Atmospheric Administration, studied ship tracking data from 2008 to 2015. They wanted to see how ship traffic changed in response to a series of clean air regulations implemented during that period. The regulations were designed to reduce ship exhaust, which causes heart and lung diseases and contributes to acid rain.

California’s first attempt to curb ship emissions came in 2009, when it implemented a rule requiring ships to use cleaner-burning, low-sulfur fuels within 45 kilometers of the mainland. By 2012, the United States had adopted the International Maritime Organization’s new clean fuel standard, which expanded the low-sulfur fuel area to anywhere within 370 kilometers of the coast. Over the following years, both state and international requirements grew increasingly strict.

Initially, ships began seeking new routes to circumvent the protected areas to avoid having to use the more expensive clean fuel. It’s not yet clear how that impacted whales, Moore says, but the results may have been mixed. Starting in 2009, for instance, ships abandoned the passage between Santa Barbara and the northern Channel Islands, opting for a longer route outside the emission-control area where they could burn regular fuel. That might have been good news for the whales in the Santa Barbara Channel, but may have created fresh problems for whales living west of the Channel Islands. Some ships also sped up to compensate for the longer distance, increasing the risk of lethal ship strikes.

By the time the full suite of air regulations was in place, many ships had swung back into shore, since the low-sulfur area was now so wide that there was little benefit to staying further from shore. But the rules did usher in one lasting change: up and down the coast, ships have slowed down to save money by burning fuel more efficiently. Before the clean air regulations took effect, ships often sailed faster than 20 knots. Today, Moore’s team found, average ship speeds have dropped to between 14 and 18 knots.

Though the researchers are still working to understand exactly how the change in ship speed might have affected specific whale populations, there are reasons to believe the effects were positive. Numerous studies have shown that slower sailing speeds reduce the threats ships pose to whales. Slower ships make less noise that could interfere with whale communication and cause fewer fatal ship strikes.

“There’s less momentum, less force, and a higher likelihood of survivability if you do have a strike,” says Jens Currie, a research analyst at the Pacific Whale Foundation who was not involved in the study.

Moore’s team estimates that the ships’ slower speeds reduced the risk of deadly collisions in the Santa Barbara Channel by 20 percent. Statewide, the number of whales that washed up on beaches because of ship strikes dropped significantly after the new rules were implemented, though Moore stresses that changes in ship traffic is just one potential factor.

Since 2005, California has launched several voluntary speed reduction programs aimed at preventing whale deaths by ship strikes. Currie says some companies have been eager to participate because “nobody wants a whale on their bow when they come into port.” He says these programs may have contributed to the slowdowns Moore’s team identified in their study.

But in general, John Calambokidis, a biologist at Cascadia Research Collective who was not involved in the research, says these voluntary efforts are “anemic.” He says Moore’s study shows that economic incentives are necessary to bring the rest of the shipping industry along.

“You have to do more than just ask ships to slow down,” he says.

In this case, the forces at work had nothing to do with whales. “These were all almost unintended consequences,” Calambokidis says. “They could change at any point.”