Wave energy development and gray whales in Oregon: Potential risk and mitigation Public Deposited

http://ir.library.oregonstate.edu/concern/technical_reports/70795844s

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  • The Oregon coast has been identified as an area with great potential for production of electricity from wave and wind energy, and development of marine renewable energy facilities are being discussed for several locations along the Oregon coast. The potential impact of this development on eastern gray whales is largely unknown, but collisions, entanglement, or displacement are all possible effects. To evaluate their potential level of exposure to such risks, gray whales were tracked from shore during their southbound and northbound migration along the central Oregon coast from December 2007 to May 2008. This study’s objective was to generate accurate, up-to-date baseline information on gray whale behavior and distribution relative to shore in an area where installation of wave-driven electricity generators has been proposed. Three observers surveyed gray whales from an observation station at Yaquina Head, Oregon (44.67675º N, 124.07956º W, 25.39 m above mean sea level) using binoculars (7x50 Fujinon) and a theodolite (Sokkia, 2 sec resolution, 30x scope) during daylight hours when environmental conditions permitted. Locations were recorded of all whales seen during scan surveys of the 200o field of view of the ocean, and of individual groups tracked during focal follows. Average distance from shore (Fig. 1), median depth of locations, and average speed were all significantly different between southbound and northbound phases of migration. 61% of all whales and 78% of mothers and calves passed within 3 nautical miles of shore, through areas of proposed wave energy development, thereby putting them at potential risk of collision, entanglement, or displacement from the structures. During winter and spring 2012, a low-powered acoustic deterrent was tested off Yaquina Head to see if it could successfully keep whales a modest distance (500 m) away from wave energy buoys in case such risks are realized. In this test, an acoustic device was moored in the migration path of gray whales and transmitted a 1-s, 1-3 kHz warble signal three times per minute during daylight experimental periods. The device was turned off during the remainder of each day to serve as control periods. Shore-based observers conducted observations using the same sampling protocol as the 2007/08 study. Whale locations were compared between experimental (active sound transmission) and control (no sound) periods to determine whether the device successfully deterred gray whales. A combination of bad weather and equipment problems resulted in a much smaller sample size than required to detect a difference in whale locations between experimental and control periods. To achieve the desired sample size will require continuing the experiment for another winter migration season and increasing power to make the zone of influence 3 km, rather than 500 m. We have prepared the necessary equipment changes and are actively seeking funding partners to create the first ever tool that could protect whales from future anthropogenic stressors, including wave energy facilities, oil spills, or other issues.
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  • Lagerquist, B. A. & B.R. Mate. 2012. Wave energy development and gray whales in Oregon: Potential risk and mitigation. In: Boehlert, G., C. Braby, A. S. Bull, M. E. Helix, S. Henkel, P. Klarin, and D. Schroeder, eds. 2013. Oregon Marine Renewable Energy Environmental Science Conference Proceedings. U.S. Department of the Interior, Bureau of Ocean Energy Management, Cooperative Agreement with Oregon State University M12AC00012. OCS Report BOEM 2013-0113. 149 pp.
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  • description.provenance : Approved for entry into archive by Maura Valentino(maura.valentino@oregonstate.edu) on 2013-02-07T00:31:03Z (GMT) No. of bitstreams: 1 Lagerquist-graywhales.pdf: 6934034 bytes, checksum: f1dee00be5a040f88b93712644ba61cf (MD5)
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