Project Title: Humpback whales and the impact of noise: Controlled Exposure Experiments
Chief Investigators: Dr Michael Noad & Prof Doug Cato
Over 4 weeks in September and October 2008, we conducted a series of 12 acoustic Controlled Exposure Experiments (CEEs) on humpback whales off the Sunshine Coast north of Brisbane. The acoustic exposures were conducted using an underwater acoustic transducer suspended from a small boat. The movements and behaviours of the whales were monitored by land-based observers before, during and after the exposures (BDA design). As in previous years, the signals used were humpback whale social sounds and a repeated rising, artificial tone. The exposures and monitoring were successful and the data collected added substantially to data collected in previous years allowing us to progress analysis of the full data set. While performing the CEEs, we also obtained biopsy skin samples from six whales and blow mucus samples from five whales.
As part of the CEEs, we attempted to place suction cup ‘Dtags’ on the backs of some whales as they moved down the coast so that these whales could be focal groups for exposure. The placement of tags was less successful than anticipated, with only three whales tagged, due to the use of inadequate equipment. We did, however, learn a great deal about Dtags in the process. Originally we planned to send a team member to Woods Hole Oceanographic Institution (WHOI) in the US to learn how to run the Dtags, but we ended up bringing Alison Stimpert, an experienced Dtag user from the Univ. Hawaii out to the field site instead to teach us about tag assembly, tag preparation, programming the computer, degaussing the magnetometers, tag calibration, deployment and data download. This was extremely instructive and provided a great deal of the necessary ‘technology transfer’ required.
In addition to the CEEs, we recorded and acoustically tracked 30 singers and at least seven groups that were producing social sounds in a variety of contexts. The tracking of singers is part of the long term monitoring of song pattern in the east Australian population and the development of acoustic census techniques for humpbacks.
We also performed a comprehensive set of test acoustic transmissions that were used to more accurately measure the propagation of sound at the study and improve our ability to measure acoustic source levels of whales and other sources of interest.
