Whales and wave power: bringing the noise to avoid collisions

Oregon researchers investigate a noise deterrent system to steer gray whales from incoming wave energy buoys.
Written by Melissa Mahony, Contributor

Weighing in at up to 40 tons, a gray whale is a formidable creature. But should it swim into a wave energy bouy tipping the scales at 200 tons, the marine mammal could be in deep trouble.

Rising and falling with the waves, the 150-kilowatt power buoys (below) capture the kinetic energy of the ocean and send it to land via cables.

By 2012,Ocean Power Technologies plans to place 10 of these buoys 2.5 miles off Reedsport, Oregon. Also in these waters are about 18,000 gray whales, migrating twice a year between Mexico and the Pacific Northwest. A 2008 study found 61 percent of these whales pass within three nautical miles of Oregon's coast, likely to avoid predation by the killer whales that swim farther out.

Anticipating scenarios in which the emerging renewable energy could harm marine life, whale expert Bruce Mate of Oregon State University's Marine Mammal Institute (MMI) is looking to keep gray whales away from wave power generators through noise. MMI will test small acoustic devices in the hopes of sonically persuading the whales to slightly detour around a 500-meter area that would surround the proposed wave farm.

While there are worries over whales becoming entangled in the transmission cables, according to Mate the major concern is blunt trauma from a collision. With thousands of pounds of pressure, the 4-to-6-inch cables are very taut. A large whale migrating at speeds of about 4 miles per hour could seriously damage itself.

During a six-hour period each day, the devices will send out a low-pitched "whoop" three times a minute. According to researchers, the sound energy (one-eighth of one watt) will be less than 1 percent of the sonar emitted from a fishing boat. Beginning in December, the researchers will observe the reactions of northbound single whales. The testing will end before mothers and their calves travel north from Baja *California in May. (*edit)

Mate says in a recent statement:

We do not even expect gray whales to react to the sound unless they are within 500 to 750 meters of the mooring location. We’re not talking about much sound here. Although baleen whales, including grays, don’t have sophisticated sonar, they are good listeners, so we hope it will alert them to be more aware.

Reliant on sonar for communication and finding food, many cetacean species are very sensitive to noise. Because adding more sounds to an already noisy ocean might negatively impact marine mammals, whether or not these devices might become standard for the industry is unknown. For now, the researchers just want some measure to deploy should the whales begin crashing into the power structures.

Mother Nature Network quotes Justin Klure of Pacific Energy Ventures:

Nobody knows if a large buoy or any other technology is going to have an impact on an ecosystem. A misstep early could set back the industry. This is hard work, it’s expensive, if you don’t have a solid foundation, we feel, that is going to cost you later.

Beyond the wave power implications, Mate hopes the study, funded by the Department of Energy, could lead to ways to keep whales from other dangerous areas, such as oil spills.

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Images: Bruce Mate and Ocean Power Technologies

This post was originally published on Smartplanet.com

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