Date: April 11, 2017
Source: NOAA Fisheries West Coast Region
A new study assessing the underwater soundscape off Southern California found that blue, fin and humpback whales experience a range of acoustic environments, including noise from shipping traffic as well as quieter areas within a national marine sanctuary. The study appeared in a special issue of Endangered Species Research focusing on ocean noise.
"Our research provides a framework that can be used to evaluate how shipping traffic affects acoustic environments and a tool to explore existing and future management strategies," said Jessica Redfern, a research biologist at NOAA Fisheries' Southwest Fisheries Science Center in La Jolla, Calif., and the lead author of the study.
Other authors include scientists from NOAA's Office of National Marine Sanctuaries and Office of Science and Technology, the National Park Service and private consulting companies. The analysis is a case study in NOAA's Ocean Noise Strategy Roadmap, which describes methods of measuring and assessing the impacts of ocean noise.
Blue whales feed in Southern California waters from about June to October, while humpback whales feed in the area from March to November and fin whales have been found there year-round. Underwater shipping noise occurs at low frequencies and these three species of large whales are low frequency hearing and communication specialists. Therefore, the potential for low frequency noise to mask communication has been identified as a primary concern. The study used U.S. Coast Guard data on ship traffic from 2009 to estimate sound levels throughout Southern California waters, including areas south and west of Point Conception and in the Channel Islands National Marine Sanctuary.