Drowned out

SFBG | Rebecca Bowe

The tiny, rigid-hull inflatable boats that researchers at Scripps Institution of Oceanography use for whale tagging are a mere fraction of the size of the blue whales they are deployed to search for. But Scripps PhD candidate Megan McKenna says there’s no reason to worry about the mammoth creatures — which can weigh as many tons as 27 elephants put together — bumping up against the boat when she reaches overboard with a pole to tag them.

“They’re just pretty mellow, I guess,” McKenna says. “There’s no flailing or anything. Some barely even notice that we’re there.” For two summers, she’s ventured out in pursuit of the endangered whales, popping short-term monitoring tags on them to learn how they behave when massive cargo shipping vessels motor past.

It’s an important question for a couple of reasons. Government funding was provided for the Scripps study after two blue whales were struck and killed by commercial shipping vessels in 2007, tragedies magnified by the fact that the marine mammals are still struggling for survival. If even two die in such collisions every few years, the entire species could be imperiled, McKenna says.

At the same time, a less-understood phenomenon has marine scientists worried that the deep-blue giants’ survival is being undermined by a subtler problem, that Jackie Dragon of San Francisco-based Pacific Environment likens to “death by a thousand cuts.” Noise generated by whirring ship propellers registers at the same frequency as the low tones whales use to communicate and forage for food, and researchers are concerned that the constant interruption is affecting their ability to engage in basic survival behavior.
Put together with an array of concerns including chemical pollution, marine debris, over-fishing, and ocean acidification, noise pollution is just coming onto the sonar of local marine sanctuary councils and federal environmental agencies, and proposed solutions are only in the fledgling stages.

At an April 8 joint meeting between the Gulf of the Farallones and Cordell Bank marine sanctuary advisory councils, the groups discussed creating a working group — bringing together stakeholders from the U.S. Coast Guard, shipping industries, and others — to establish a set of recommendations for how to regulate noise pollution in the sanctuaries.

“The purpose is to better understand the issue from the standpoint of the sanctuary,” explains Lance Morgan, who chairs the Cordell Bank council. “Ideally, we’d produce a report that says, here’s what we think the issues are.”

Yet Morgan acknowledges that it won’t be easy to get the federal government to impose new sanctuary regulations since there are still so many outstanding questions. “We’re learning a lot about the acoustic environment,” he says. One concern is whether whales are actually able to perceive the sound of the giant shipping vessels, he notes, since the environment has become so noisy. If they can’t hear the ships, they’re at a much higher risk of collision. “We certainly know we can drown out whale calls in certain situations,” he says, “but what does that mean in the long term?”

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