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Naval sonar has been linked to mass strandings of otherwise-healthy whales for nearly two decades, but the precise mechanisms of how it affects whales has eluded scientists. Now, researchers have explained key details of how this disruptive signal triggers behavior in some whales that ends in death.
Previously, necropsies of beaked whales from multiple stranding incidents found nitrogen bubbles in their body tissues, a hallmark of decompression sickness, or "the bends." This dangerous condition also affects scuba divers when they rise too rapidly from deep water; it can cause pain, paralysis and even death.
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Mass strandings of Cuvier's beaked whales (Ziphius cavirostris) were almost unheard of prior to 1960, but that changed with the introduction of midfrequency active sonar (MFAS) in naval exercises in the open ocean. This type of sonar, developed in the 1950s for submarine detection, operates in a range of 4.5 to 5.5 kHz, according to the study. After this sonar appeared, mass stranding events soon skyrocketed for beaked whales, with 121 such strandings taking place between 1960 and 2004, the researchers wrote.
Scientists - Connection - Mass - Strandings - Cuvier
Scientists first noted a connection between mass strandings of Cuvier's beaked whales and naval exercises using sonar in the late 1980s, lead study author Yara Bernaldo de Quirós, a researcher at the Institute for Animal Health and Food Safety at the University of Las Palmas de Gran Canaria in Spain, told Live Science in an email.
That link strengthened after similar stranding events in Greece in 1996 and in the Bahamas in 2000, de Quíros added. And in September 2002, when 14 beaked whales stranded in the Canary Islands during a NATO naval exercise, veterinary pathologists discovered lesions in the animals that were "consistent with a decompression sickness," de...
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