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ATI's Underwater Acoustics for Biologists and Conservation Managers: A comprehensive tutorial designed for environmental professionals
Dr. Orest Diachok is a Marine Biophysicist at the Johns Hopkins University, Applied Physics Laboratory.
Dr. Diachok has over 40 years experience in acoustical oceanography, and has published numerous scientific papers. His career has included tours with the Naval Oceanographic Office, Naval Research Laboratory and NATO Undersea Research Centre, where he served as Chief Scientist. During the past 16 years his work has focused on estimation of biological parameters from acoustic measurements in the ocean. During this period he also wrote the required Environmental Assessments for his experiments. Dr. Diachok is a Fellow of the Acoustical Society of America.
Acoustical Society of America - 151st Meeting Press Luncheon Press Release
Presenter: Orest Diachok, Johns Hopkins Applied Physics Laboratory, Laurel, MD (firstname.lastname@example.org)
In the Gulf of Alaska, humpback whales work in groups to capture herring, with one whale broadcasting sound at a herring school to drive them to the water surface. A second whale blows a "net" of bubbles to encircle the rising school. As Orest Diachok of the Johns Hopkins University Applied Physics Laboratory in Laurel, MD reports, during this process one or more of the whales emits long "trumpet" tones at several different frequencies, one of which resonates with, and is attenuated (absorbed) by the swim bladders of the herring (analogous to x-rays being absorbed by water in human lungs). Diachok proposes that the whales might use this phenomenon to infer the fish length, species, and size of school.
Orest Diachok, a research physicist at Johns Hopkins University, told Discovery News that the killer whale study provides "compelling evidence on the function of tail slaps, much more compelling than previous studies of this phenomenon."As for the herring flatulence, Diachok agreed the fish may do this to facilitate escape, but he said it also might just be inadvertent.Diachok and his team discovered that whales use similar bubbles to their own advantage.Diachok and his colleagues believe whales may even classify fish before they catch them.Diachok explained, "If one humpback transmits a series of tones, like plucking all the strings of a harp, then the listening (bottom) whale may notice that he can hear all of the tones, except for the one, which corresponds to the resonance frequency of fish swim bladders when the school of fish is swimming between the transmitting and listening whale."
Acoustical Society of America - 151st Meeting Press Release
As Orest Diachok of the Johns Hopkins University Applied Physics Laboratory (email@example.com) in Laurel, MD reports, during this process one or more of the whales emits long "trumpet" tones at several different frequencies, one of which resonates with, and is attenuated (absorbed) by the swim bladders of the herring (analogous to x-rays being absorbed by water in human lungs).
Diachok proposes that the whales might use this phenomenon to infer the fish length, species, and size of school (4aA05). What whales may do naturally is something that fisheries managers covet: Diachok and his collaborators have been working toward developing artificial acoustic systems that work in much the same way to detect and monitor fish populations.
Rhode Island news | projo.com | The Providence Journal | Local News
OREST DIACHOK, 65, from Johns Hopkins University, decided to study sound early in his career, after he got an offer to work for the Navy, measuring gravity at sea, he said.He found that naval officers, who trusted sonar technology, had no respect for any scientists -- except the experts in acoustics, he said.Diachok has studied the sounds made by humpback whales.He theorizes that whales might use sound to not only detect schools of fish, but to determine the composition of the schools.Imagine two whales on opposite sides of a school, he said.