Sea Technology

JUL 2018

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 17 of 44 July 2018 | ST 17 ago, this fascinating discov- ery was made by listening to the sounds of the ocean. This discovery helped create the modern conservation move- ment "Save The Whale." The subsequent album produced by Dr. Roger Payne, "Song of The Humpback Whale," is the most successful natural history recording ever made. Today, it is still unclear why only male humpback whales sing. Dr. Jim Darling, a humpback whale song ex- pert from Whale Trust Maui in Hawaii, is in pursuit of this mystery. Darling and his team hypothesize the song may be a way for individual males to recognize how closely associated they are with other males and may determine if specific males cooperate or compete for females. Darling's research focuses on comparing songs from different regions within the North Pacific Basin to identify the similarities and differences between them. JRF is exploring the hypothesis that humpback whales may be congregating around shallow-water seamounts between Hawaii and Mexico, which provide diverse ecosystems for marine life. Even one record of a hump- back song in the deep waters would be significant and could lead to further investigations. Furthermore, track- ing their song and migration patterns could shed some light on biological responses to environmental changes, including climate change and global warming. The HUMPACS Mission JRF has partnered with Darling to search for hump- back whales by listening for their song in the deeper wa- ters between their known breeding grounds. To perform this mission, they used a Wave Glider SV3, called Euro- pa, to transect the Pacific between Hawaii and Mexico. Europa is a wave- and solar-powered unmanned surface vehicle made by Liquid Robotics. The vehicle is loaded with high-tech listening and monitoring gear that contain sound triggers and satellite uplinks to collect, record and transmit data. JRF pro- grammed Europa to store all recordings on an onboard solid-state drive, although they can request audio files at will. If JRF hears some- thing of interest, they can command Europa to survey that area before proceeding. The mission is a little like searching for a needle in a haystack. However, the humpbacks' song has a vast range of frequencies and amplitude; therefore, it is a large needle in a haystack. The data they collect are crit- ical to studies of behavior and abundance of humpback whales in the North Pacific Basin. The HUMPACS mission, covering more than 2,000 nautical miles, is the first survey of seamounts from Ha- waii to the Baja California Seamount Province searching for these humpback whales. Ships, satellites and subma- rines have surveyed the Pacific; however, never at the slow pace of 1.5 kt. over several months while record- ing the acoustic soundscape 24/7, collecting sea surface temperatures, salinity levels, ocean currents, weather data and taking above and underwater photos, and cer- tainly never from an unmanned surface vehicle. Soundscapes, Marine Ecoacoustics Ecoacoustics is a relatively new field of science. It is the study of sounds and their relationship with the en- vironment over a wide range of scales (both spatial and temporal). Scientists investigate sounds to understand their evolution, functions and properties under environ- mental stressors and changes. They use these sounds as tools to monitor ecological factors, such as biotic and abiotic relationships, animal behavior, diversity, abun- dance and distribution. (Top) Europa, the SV3 Wave Glider. (Bottom) A spectro- gram of humpback whale WAV file (0 to 10 kHz): a graphical representation of mp3 audio.

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