Sunday was another great day for Cetacean Research along the Antarctic Peninsula (just in case you’d forgotten the acronym). We worked in Charlotte Bay, the northernmost of the four bays along the Peninsula in which we study whales. It’s a big bay, exposed to wind and often clogged with ice, so we don’t get up here often. Yesterday we were glad we made the journey.
We started in the morning with a survey of whales from the edge of the ice – a thick layer of brash, ice bergs and small bergy bits that the small boats could penetrate (just), but much too thick for the Point Sur – out to the mouth of the bay. Lots of humpbacks and minkes near the ice, but not much of anything further out. After lunch we returned to the ice edge, deployed the small boats and the Point Sur mapped krill in the open water – Doug will post about that later. We deployed two consecutive Acousonde tags on humpbacks – both lasted about four hours or so. One whale moved right into the ice and Reny had to use her super tag locating powers to recover the Acousonde from under a thick layer of frozen ocean.
For many of us, however, the day’s highlight came after dinner. We were heading out to tag the second humpback when John spotted killer whales skulking along the shoreline. So we quickly deployed a tag on a very sleepy humpback (an epic event that will be recounted later) and then followed the killer whales into the ice. Way into the ice. There are at least four different types of killer whales in the Antarctic; analysis of their mitochondrial genomes indicates that they are all different species, yet to be fully described. Very cool. The ones we followed in Charlotte Bay were the largest form; mammal-eating killer whales that hunt co-operatively in the pack ice (referred to as Large Type B killer whales in John and Bob’s shorthand). You can read more about their amazing hunting strategies here. These big killer whales are the world’s largest top predators.
We watched as nine of these enormous killer whales worked their way to the head of the bay through the thickest ice, stopping to spy-hop and breathe in small open patches of water. John and Bob were very excited to deploy a satellite-linked dive recorder on the dorsal fin of a resplendent adult male and we collected photo-ID images and a biopsy sample. Unfortunately or fortunately (depending on your perspective – both points of view were represented in the boat), the killer whales did not attack any of the young minke whales or seals in the ice. But we can follow their movements from data relayed by the satellite tag, so Reny and Matt may yet have an opportunity to fulfill their blood lust. Stay tuned…