Sperm Whale Seismic Study (SWSS)

About mid-night last night, we turned on the ADCP to measure currents and the flow through system to measure temperature, salinity, and fluorescence at about 3.5 meters depth. We deployed the two hydrophone arrays in the middle of the night. We then took an XBT and found the depth of 15C isotherm was 202 meters. Ten nm later it was 183 m. Currents were exhibiting a cyclonic circulation (counterclockwise swirl). But we heard no sperm whales during the night.

In the morning, the sea state was too rough to launch the small boats to extend our area of observations. The wind generated small white caps that made visual observations more difficult. But both the acoustic and visual teams maintained their watches. No whales were seen or heard along our transit across the southern part of the cyclone.

We turned southwest toward a region where we had seen whales in Leg 1. In mid-afternoon (about 14:45 local time), the visual team spotted a sperm whale and the acoustics team heard two or more whales. The seas still were too rough to launch the tag boats. There were 3 whales, so we stayed with the animals to provide experience for the new members of the visual and acoustic teams. During this period a group of 15-25 melon-headed whales approached the Gyre. A recording of their sounds was made. About an hour before sunset three additional whales joined the three we were tracking. We will track these six animals acoustically as long as we can tonight.