After the winds of yesterday, it was a relief today to have winds mostly around 10 knots or less. But swells and waves remained from yesterday, creating difficulties for the visual observers. The acoustic monitoring worked well, and we set a course outside of our normal survey tracks in order to get the best weather conditions we could find for beaked whales. Twice during the day, acoustics got good enough detections to direct the ship nearby the whales, get a bearing, and orient the ship for optimal location for the visual observers to monitor the location where the whales were heard. Both times the visual observers were able to sight whales even though the visibility conditions were marginal. Unfortunately, the conditions were too rough to attempt tagging. We considered using a large workboat from the ship for tagging, but even then the conditions were not good enough.
The tag team kept itself busy analyzing data from one of the tagged pilot whales from earlier in the cruise. The dive profile shows that this whale spent most of its time near the surface in the top 15 m, but it did make one deep dive to nearly 650 m that lasted 11 min. Even though we had great observation conditions of the pilot whales, none of the visual observers had any idea that the whale had made this dive. The whale made echolocation clicks starting at the red asterisk and ending at the green asterisk. The black asterisks in between mark times that the whale accelerated the clicks, which we think means that she had identified a prey item she wanted, and she attempted to capture it. The recordings from the surface also include lots of social calling. All in all, a fascinating glimpse into a few hours in the life of these whales.
» Listen to Pilot Whale Call 1Social calls of pilot whales as recorded by the Dtag. The image to the right shows the spectrogram (visual representation) of the call.
» Listen to Pilot Whale Call 2
Social calls of pilot whales as recorded by the Dtag. The image to the right shows the spectrogram (visual representation) of the call.
