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Whales Now Live in a World of “Acoustic Smog”

By Laura Erickson
graphic showing the noise of shipping traffic drowning out the vocalizations of whales
These two graphics show the acoustic scene in the waters outside Boston Harbor. Each pale blue dot represents the sound energy from a calling North Atlantic right whale. On the left, the whales are calling without commercial ship noise. On the right, the large colorful area radiating from the red dot is noise from a commercial ship entering the harbor. The ship’s noise swamps the whales’ vocalizations over a wide area.

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Ultra-low songs of the great whales can be heard many hundreds of miles across an ocean, providing communication networks that support the social fabric for these acoustically dependent leviathans. Christopher W. Clark, I. P. Johnson Director of the Bioacoustics Research Program (BRP) at the Cornell Lab of Ornithology, says that the rising tide of ocean noise from human activities is making it increasingly difficult for whales to hear each other and depriving them of critical opportunities to mate, find food, and navigate. Chris is one of a handful of scientists documenting the rise in ocean noise and carefully studying how whales respond to these changes. He has observed that some species stop communicating with each other as huge commercial ships pass through their habitats. When the noise level rises, whales stop calling and males stop singing. He suspects that when these things happen whales can’t alert one another about rich food resources and so don’t aggregate around food patches, or they have difficulty finding mates.

“Many female right whales have lost their thick layer of fat,” Chris says. “When they don’t have enough blubber, they don’t reproduce. So noise could be reducing their opportunities to tell each other where the food is, which in turn reduces the amount of food they eat. They become skinny and have a calf once every five to six years—not once every three years. Ninety-eight percent of the world’s commerce travels on the backs of ships. In some places all those ships bringing us stuff might be having real impacts on whale populations, not just by running the whales over, but by depriving them of their ability to listen and communicate.”

The BRP team works with government, industry, and other scientists to explore ways to reduce increasing ocean noise levels in the belief that a normally quiet ocean is a healthy ocean, and a healthy ocean for whales is a healthy ocean for humans.

The major contributor to ocean noise comes from shipping, but sounds from other human activities, such as oil and gas exploration, construction, and Navy sonars are also a concern. Unlike noises from shipping and construction, which are waste products, sounds for energy exploration and military sonar are designed for specific purposes. Energy exploration relies on arrays of airguns that generate intense seismic impulses to probe beneath the seafloor for oil and gas, whereas military sonars produce intense, modulated sounds to probe for submarines in the ocean.

BRP is actively engaged in providing objective scientific data to inform decision making and enable effective solutions for all of these human activities. A multi-year program involving collaboration between BRP, Woods Hole Oceanographic Institution, and liquefied-natural-gas offshore terminal developers, Excelerate Energy and Suez Energy, has created the first real-time detection and vessel warning system for critically endangered North Atlantic right whales. BRP is partnering with Imperial Oil in the Canadian Beaufort Sea to provide baseline monitoring information in support of environmental permitting processes before the company starts seismic testing. BRP recently conducted a training workshop for 10 of the Navy’s top marine mammal acoustics specialists, and is conducting marine mammal acoustic surveys during naval training exercises along the Eastern seaboard. BRP scientists are working with the North Slope Borough in Barrow, Alaska, to acoustically monitor the annual bowhead migration. In the Stellwagon Bank National Marine Sanctuary, BRP is working cooperatively with National Oceanic and Atmospheric Administration scientists to establish baseline sanctuary noise budgets to closely monitor the acoustic environment and the impacts of shipping noise on seasonally resident endangered whales.

Chris said, “Most people don’t realize that sounds in the ocean, especially low-pitched sounds, travel really, really efficiently. The reason I can hear a blue whale 1,600 miles away is because the whales have adapted their voices to take advantage of this incredible efficiency. Different whale species depend on these different opportunities for long-distance communication. What we’re finally doing is measuring and predicting how all these human acoustic activities deprive whales from establishing and maintaining their communication networks. Off the East Coast, some species are losing 80 to 90 percent of their acoustic communication opportunities just from the daily smog of commercial shipping. This is one of the invisible costs that we impose on the ocean and the whales when we go to the store to buy more stuff. It is simply not sustainable. Not for the whales, not for the ocean, and not for us.”


Originally published in the October 2009 issue of BirdScope.

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