Mammal-eating killer whale diving behavior

For more information contact Robin W. Baird at rwbaird (at) cascadiaresearch.org

Sept. 10
Hi Susan, On Sunday afternoon (September 10) we encountered a group of transients in Admiralty Inlet near Bush Point. We followed the group northbound, though they didn't cover much ground over the few hours we were with them (last seen south of Marrowstone Point, slowly heading north into a flood current). Whales present included T101, T101A, T101C, T102, T100, T100C, T100B, another T100 calf (presumably T100D), T90, T124, T124D, T124E, and possibly T124C. We deployed one of our suction-cup attached time-depth recorders on T100B. During the period we followed the group there were two kills, a porpoise (we collected a small muscle sample to confirm this genetically), and a harbor seal. The next day we found the tag floating SW of Hein Bank (located using the VHF radio signal), and when we downloaded the data confirmed the tag had stayed on 13 hours, coming off at about 4:45 on Monday morning. Some interesting dive patterns that will take a while to analyze, but particularly interesting that there were clear changes in diving behavior associated with the two kills, with the whales rapidly ascending (from about 10-15 m) and then diving much deeper (34-55 m). I've put some photos and an example of the dive data on the Cascadia web site, at www.cascadiaresearch.org/robin/transientdive.htm (for those who are squeamish, you may not want to look at the last photo). Robin Baird
Cascadia Research