High-frequency Acoustic Recording Package (HARP) for long-term monitoring of marine mammals

Abstract

Advancements in low-power and high-data-capacity computer technology during the past decade have been adapted to autonomously record sounds from whales over long time periods. Acoustic monitoring of whales has advantages over traditional visual surveys including greater detection ranges, continuous long-term monitoring in remote locations under various weather conditions, and lower cost. One currently used tool for providing long-term acoustic monitoring of marine mammals is an autonomous acoustic recording package (ARP) which uses a tethered hydrophone above a seafloor-mounted instrument frame. Since 2000, ARPs have been deployed to record baleen whale sounds in the Bering Sea, in the Beaufort Sea, in the Gulf of Alaska, off the coast of southern California, around Antarctica and near Hawaii. ARP data have provided new information on the seasonal presence, abundance, call character and patterns of calling whales. The need for a broader-band, higher-data capacity system capable of recording odontocete whales, dolphins and porpoises for long time periods has prompted the development of a High-frequency Acoustic Recording Package (HARP). The HARP design is described and data analysis strategies are discussed using examples of HARP broad-band (sample rates up to 200 kHz) recorded data.