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<\/div>The minke whale is a smaller species of baleen whale<\/p>\n
Kerstin Meyer\/Getty Images<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
Brainwave testing of two young baleen whales has revealed they can hear higher frequency sounds than previously thought, forcing researchers to rethink how the ocean\u2019s largest animals respond to predators and human noises.<\/p>\n
\u201cThis is truly groundbreaking work,\u201d says Susan Parks<\/a> at Syracuse University in New York, who wasn\u2019t involved in the new study. \u201cDirectly measuring the hearing of a wild baleen whale is something the researchers in the field have been working towards for decades\u2026 This is, to my knowledge, the first successful test of this method with a baleen whale.\u201d<\/p>\n But baleen whales include the largest animals on Earth, and the study method of temporarily restraining them for a hearing test isn\u2019t easy. \u201cThe body size of most baleen whales is too large for the approach to be effective,\u201d says Dorian Houser<\/a> at the National Marine Mammal Foundation, a nonprofit organisation based in California. So Houser and his colleagues turned to a relatively small baleen species called the minke whale.<\/p>\n <\/p>\n The researchers examined the migratory route of minke whales along the coast of Norway and found a natural channel between two islands, where they used net barriers and boats to guide two whales \u2013 each about 3 to 5 metres in length \u2013 into a fish farm enclosure with a drop-down net door. Researchers then used a roller system to pull up a net and hold the teenage animals partially submerged at the water\u2019s surface.<\/p>\n The hearing test involved placing two gold-plated electrodes with silicone suction cups on each whale\u2019s skin near its blowhole and dorsal fin, which enabled the researchers to record brainwave signals. They measured how the whales\u2019 brains responded to sounds played from an underwater speaker for about 30 minutes for one whale and 90 minutes for the other.<\/p>\n \n