Sperm Whale Seismic Study (SWSS)

We transited through the night back to the south side of the region with the cyclonic circulation where sperm whales were encountered earlier in the cruise. By morning, seas were too choppy to deploy the Rigid-Hull Inflatable Boats (RHIBs) for the purpose of extending our search area. Small white caps provided less than ideal conditions for the visual team. Winds died down a bit in mid afternoon. At approximately 19:40 UTC, acoustics heard a sperm whale and maneuvered Gyre into the direction of the sound. Two additional whales were heard, making three animals in this group. Within an hour, the visual team had spotted the blows of two separate whales. 3-D passive acoustic tracking data were recorded. By about 22:30 UTC, RHIB-2 was launched as the tag boat and the Gyre's Avon was launched as the photo-id boat. RHIB personnel reported there were 3-4 animals, none of which had been tagged and one of which was too small to tag. No tags were deployed.

Both RHIBs were recovered by about 00:45 UTC on 18 June 2005. The 38 kHz fishery echo sounder was deployed between 23:00 UTC and 01:00 UTC on 18 June 2005, and the 38 kHz ADCP was turned off while the echo sounder was on. Seven XBTs were deployed during the transit, with the depth of the 15C isotherm decreasing from 244 meters early in the day to 200 meters as we entered the region on the south side of the cyclonic circulation feature.

Currents in the region of the whales were about 1 knot and generally were eastward, consistent with being on the south side of a cyclonic circulation feature. The fluke photograph that was included in the report for 15 June 2005 was taken at approximately 26.87N, 95.21W. Comparison with the fluke photo-id catalogue for the Gulf suggests this sperm whale may have been photographed at approximately 27.43N, 93.82W on a SWSS cruise two years ago on 3 June 2003.