Paper by Patrick Miller (SMRU)
In 2006 and 2008, an international collaborative team of scientists from St Andrews, FFI in Norway, and TNO in Holland conducted a series of dose-response experiments to describe the influence of sonar frequency on behavioural responsiveness of cetaceans. The experiments consist of attaching a sound and movement-recording Dtag to a subject whale, and visually observing the tagged animal and group members before, during, and after controlled exposures by 1-2 kHz or 6-7 kHz sonar signal transmitted by a boat approaching the whales at 8knots. Control stimuli include no-sonar silent approaches and playback of killer whale sounds. To date, we have conducted 3 experiments with killer whales, 4 with pilot whales and 1 with a sperm whale. Another trial is scheduled for May-June 2009. In our dataset, we have noted striking behavioural changes coincident with the sonar presentations, but these changes seem quite variable both within and across species, likely reflecting the diverse behavioural context in which the sonar signals were played to the animals. Standard frequentist statistical approaches are likely to be challenging with our data, due to a small sample size and variability in responses observed, so I hope to consider other statistical approaches by which we might describe what we can infer from our dataset about response thresholds, response type, and biological significance of responses.