During the past week we finished deploying satellite tags for the first leg of the 2018 Atlantic Behavioral Response (BRS) study. Then we conducted our first Controlled Exposure Experiment (CEE) with a mid-frequency sonar system deployed from a Navy destroyer. We also conducted another CEE with our scaled sound source, so all together it was a very busy week for us off Cape Hatteras.
Despite less than ideal weather, we worked with Daniel Webster from the Cascadia Research Collective to deploy satellite-linked transmitters on 10 short-finned pilot whales and two Cuvier’s beaked whales during the first leg of the 2018 Atlantic BRS. These tags transmit data on the diving behavior of tagged whales and allow us to estimate the position of the tagged whales through Service ARGOS. The position estimates from ARGOS are fairly imprecise, so we have been experimenting with FastLoc tags on pilot whales – these tags obtain GPS estimates of location and transmit these locations to orbiting satellites. So far, the FastLoc tags are working quite well.
Our most significant accomplishment during this period was the CEE we conducted with the USS Nitze, a guided missile destroyer based in Norfolk, Virginia. CEEs with Navy vessels require an extremely high level of co-ordination between our research team and the vessel. The day before the experiment, we determined the approximate location of one of our tagged beaked whales and provided this information to the Nitze, so that the vessel could transit overnight to the approximate starting point of the experimental trial.
On the morning of the trial, our crew on the RV Barber visually relocated the tagged whale, providing an exact position of the animal. Meanwhile, Brandon Southall and Doug Nowacek were running real-time acoustic propagation models to determine how far the vessel should be from the tagged whale to achieve a specific received level of the sonar signal. This allowed us to provide specific start and end positions for the destroyer. We successfully conduct the hour-long trial and, once the field season is completed, we’ll examine the behavioral response of the focal beaked whale plus the other 11 tagged whales. We appreciate the cooperation of the officers and crew of the Nitze in conducting the CEE and for fitting the trial into their busy training schedule.
While all this was happening, Heather Foley from Duke and Tiffany Keenan-Bateman from UNCW were in the air, listening for the radio signals from a couple of wayward Digital Acoustic Tags. Heather and Tiffany flew over the Barber and our focal beaked whale and also observed a group of sperm whales and a solitary fin whale in the Gulf Stream.
