Buoys watch for whales at risk

 作者:姬溏畸     |      日期:2019-03-08 02:20:00
By Duncan Graham-Rowe AN ARRAY of buoys now under construction will ensure that ships and trawlers steer clear of endangered whales that are swimming off the Massachusetts coast. US legislation that came into force last week requires ships of more than 300 tonnes to report to the local coastguard when entering critical habitats of the right whale, Eubalaena glacialis. The coastguard can then issue instructions to the vessels to avoid the endangered whales—provided the animals’ whereabouts are known. This is where the buoys come in. There are thought to be fewer than 300 whales left in the relatively shallow waters off Cape Cod. The most effective way of monitoring them is to use spotter planes. But according to Jonathon Gordon of the International Fund for Animal Welfare in Oxford, the planes are hampered during bad weather, which is when the whales need protection most. The buoys will operate around the clock, using hydrophones—underwater microphones—designed to detect the frequency range of right-whale song, which is typically between 100 and 120 hertz, says Ken Ekstrom an engineer at the Massachusetts Institute of Technology who worked on the design. Information from the buoys will be relayed to an onshore receiving station by radio. By analysing signals from the entire array,