Cetaceans and naval sonar : the 3S-2009 cruise report

There is a pressing need to quantify the sensitivity of cetaceans to behavioral disturbance by naval sonar. The 3S group currently involving four main partners (FFI, TNO, SMRU and WHOI) conducted in May-June 2009 a research trial in Norwegian waters to investigate behavioral reactions of killer whales, pilot whales and sperm whales to Low Frequency Active Sonar (LFAS) and Mid Frequency Active Sonar (MFAS) signals, in order to establish safety limits for sonar operations. The research group consisted of 29 scientists from 9 different countries. We have deployed 17 dtags to sperm whales, killer whales and pilot whales. These tags have recorded the behavior of the tagged animal for 176 hrs total. We have conducted 6 sonar exposure experiments using the Socrates sonar source transmitting signals in different frequency bands and waveforms and conducted the same number of negative and positive controls using vessel approaches without sonar transmission and playbacks of killer whale sounds, respectively. In addition we have conducted a pilot experiment on how to study effects of ramp up using a different exposure protocol, and collected baseline data on all three species. In carrying out these experiments we have also systematically collected focal follow and group behavioral data according to predefined protocols and we have collected data on the effects of tagging. We also achieved significant progress in developing new techniques for deployments of tags using both the remote launching system ARTS and a specially designed setup with a very long hand held pole for sperm whale tagging. In addition, we have collected data on the acoustic transmission conditions in the environment and collected data on passive acoustic detection and tracking of marine mammals from two towed arrays (Delphinus (TNO) and Beamer (SMRU). Conducting behavioral response studies is an expensive and complicated operation involving heavy logistics, operation of sophisticated sonar equipment and collection of behavioral data of animals which are mostly invisible to humans. This is the third research cruise conducted by the 3S-team (triple S goes triple), and the total outcome of this international collaboration is 15 experiments, most of them involving multiple exposures, on three different species of cetaceans (sperm whales, long finned pilot whales and killer whales). This effort vastly increases the total amount of data available to address the question of behavioral effects of sonar on cetaceans. With the addition of some data on baseline behavior, we now believe we have a solid data set to address the questions of how our target species are affected by different sonar signals. This information should be used to make science based mitigation procedures which can better balance operational requirements and unintended environmental consequences of sonar use.