Sometimes work can be intense in the ice tower. The watch starts lazily with a sighting once every 10 minutes or so, but then, all of a sudden, the elements align and we have barely enough time to record everything we see.
Last week there were a few hours like that during my shift. The sun was setting (an Antarctic sunset can easily last a full hour) and the ship was steaming through pack ice with few leads. There were lots of small, molting Adelie penguins that kept running away from the RV Palmer with their funny gait. I also saw an emperor penguin on a nice, strong floe, but it was inaccessible because the ice around it was both too thin to walk on and too thick for a zodiac to pass through.
Far ahead, a tall dorsal fin pierced through the water. It didn’t show again, so I recorded it as an “unidentified cetacean.” Fifteen minutes later we saw a pod of about 30 orcas in front of the ship. They were “B”-type orcas, seal eaters. Slapping the water with their tails (maybe to threaten any non-killer whale in the area) and “spyhopping” (sticking their heads vertically out of the water) to check each floe for seals, the orcas gave a terrifying demonstration of playful power. If any seal had been around, it wouldn’t have lived through the night. The Palmer’s first mate slowed down the ship, and for an hour the ship became a tour vessel, with everyone standing on the bow taking pictures and hooting at each appearance of the orcas.
In Antarctica, killer whales belong to three different “ecotypes.” Not only do these differ morphologically (the B- and C-types have yellowish dorsal “capes” while the A-types don’t, and the former two are considerably smaller than A-types with larger, white eye patches), but they also have different ecological niches. A-types are found in open waters, mainly near the Antarctic Peninsula and feed primarily on other cetaceans such as minke whales. B-types are seal eaters and occur in the pack ice. They’re also known for occasionally feeding on penguins. The smallest of the lot, the C-types, occur closest to the fast-ice and are frequently seen off McMurdo Station. They are fish eaters and their populations might be in decline due to ongoing fishing of Antarctic toothfish (Chilean seabass). These differences between ecotypes are such that some scientists suspect they may be different species altogether.
In 2009, I attended a presentation by Dr. Bob Pitman, a top killer whale expert from NOAA. He showed us footage of a pod of B-types swimming in a row at great speed. They were headed toward a seal hauled out on a floe. Just before reaching the ice they all ducked underneath it, letting the large wake they created wash over the floe, carrying along the unlucky seal. Another orca was conveniently placed on the opposite side to intercept the animal.
Stay tuned for more adventures from the RV Palmer!