Underwater Noise Decreases Whale Communications in Stellwagen Bank Sanctuary
According to a NOAA-led paper published recently in the journal Conservation Biology, high levels of background noise, mainly due to ships, have reduced the ability of critically endangered North Atlantic right whales to communicate with each other by about two-thirds. From 2007 until 2010, scientists from Stellwagen Bank National Marine Sanctuary, Cornell Lab of Ornithology, NOAA’s Northeast Fisheries Science Center, and Marine Acoustics Inc. used an array of acoustic recorders to monitor noise levels, measure levels of sound associated with vessels, and to record distinctive sounds made by multiple species of endangered baleen whales, including “up-calls” made by right whales to maintain contact with each other. Vessel-tracking data from the U.S. Coast Guard’s Automatic Identification System was used to calculate noise from vessels inside and outside the sanctuary. By further comparing noise levels from commercial ships today with historically lower noise conditions nearly a half-century ago, the authors estimate that right whales have lost, on average, 63 to 67 percent of their communication space in the sanctuary and surrounding waters. The authors suggest that the impacts of chronic and wide-ranging noise should be incorporated into comprehensive plans that seek to manage the cumulative effects of offshore human activities on marine species and their habitats.