With all of the success we have had to date on this trip, the one remaining target on our list is to deploy a multi-sensor suction cup tag on an Antarctic minke whale. These elusive and abundant ice-loving whales are at the center of considerable debate and discussion within the scientific community, yet very little is known about their behavior and habits. We achieved a significant milestone with the successful deployment of so many satellite tags that will monitor the long-term movement patterns of the whales around the Antarctic Peninsula. But, to date, we have no data on their fine-scale movement and diving behavior. This would change today.
As with so many of our most memorable discoveries, Wilhelmina Bay was the theater. The blue sky ceiling and crown of craggy peaks were wrapped up in a thick layer of low, grey clouds. The once open water was plastered with ice floes broken from the fast ice once connected deep inside of Piccard Cove. These snow white geometric puzzle pieces covered almost half of the open space, and the still air overnight had frozen much of the rest of the surface in a plastic, crunchy translucent film. The remaining open water glimmered, opposing the matted finish of the newly frozen sea. From a safe distance outside of and high above the ice, we saw a few distinctive puffs of breath appear deep inside the bay. The small boats were launched and soon we were weaving our way through the maze of ice towards minke whales. At first, we thought a handful were around us, and we were excited about the prospects of tagging one, since this is how they appeared on previous days. As we approached though, from under the rigid edge of the pack ice, minke whales appeared en masse. Surrounded by boiling ocean and heaving breaths, we counted nearly 50 whales! We were taken aback not only by the number of whales, but the seemingly social and coordinated movements of the group. And, best of all, they took no notice to our presence among their herd.
Andy deftly maneuvered our boat in and among the 20-30 foot torpedoes, and it was clear that we would have our best opportunity ever to deploy our multi-sensor recording tag. We were all nervous, frightened, excited, and giddy with anticipation. Dorsal fins of all shapes and sizes appeared, knifing through the water: round, sickle-shaped, triangular, nicked, notched, bent, curved. Behind the sharp point of the rostrum, each whale varied from titanium grey to white, with splotches of papaya-colored diatoms along the flanks and belly.
The tags we are using are an engineering marvel. They stick to the back of the whale with 4 small silicon suction cups. The tag itself, and its floatation, are about the size of a remote control. The tag measures the pitch, roll, heading, depth, temperature, and acceleration of the whale 10 times per second. As well, it also records all of the sounds that the animal makes and those in the surrounding environment. Once deployed, the tag remains on the whale until the suction cups give way, sometimes 24 hours later. In order to keep track of the whale, a small VHF transmitter emits a friendly beep whenever it is above the surface and we can track the whale with antennas and receivers. easier said than done, especially with an animal rarely at the surface and one that slinks around among the ice floes almost invisible from the water line.
We were ready though. As Doug and Nick shouted out the position of whales around us, Andy guided us, putting the bow of the ship just behind and to the side of a couple of whales. The group was approaching the ice edge, preparing to go down, go under, and go deep into the habitat that only they can negotiate. With only a couple of feet to spare, each animal expelled one final breath and inhaled deeply, arched its back acutely, and slid under, its dorsal fin inches from the edge. Still moving rather quickly, and only 20 feet from the ice edge, the whale off our bow exploded at the surface. I readied myself moments before when, from my pulpit above, I could see the whale tip its rostrum up and begin to surface. I could feel the approaching white curtain and pushed the tag pole down. The tag found purchase halfway between the blow hole and the dorsal fin, along the midline of the animal, high on its back. It was solidly attached. We had just tagged an Antarctic Minke whale.
The shouts of joy were quickly tempered with the realization that our tag, now attached to an ice-loving whale, was being taken somewhere below the ice around us. Would it stay on the whale or would it dislodge and float up only to find the underside of the impenetrable ice and never be heard from again? We were freaked out. After the longest 3 minutes of our trip, and enough heartbeats for an hour, the whales began to erupt from the ice edge a kilometer away from us. We moved closer, looking, listening, hoping, that one of these whales would surface with the tag and we would hear the siren sounds of the VHF chirping. Nearly all of the whales were up now, breathing heavily, yet no tag. We looked at each other, tension present and accounted for, and then we heard it. Next we saw it, and finally we believed it. The tag was riding high, settled on the whale, and collecting data!
The next few hours were magical. The 51st whale in a group of 50, we were treated to sights and sounds that none of us will ever forget. The whales lunged, rolled, glided, and played around us. At times, they fed, sometimes they rested cooly, and often they dove. But they always came back. As we got into a rhythm with the whales, making looping circuits around the bay and forays under the ice, something changed. A few of the whales began charging and breaching, porpoising and splashing. Soon the group of 50 was no more and we were left with a diminished herd of 10 whales. They continued on and we followed. Smiles plastered to our faces, we talked nonstop about what the whale was doing, what it might be doing, what we thought we knew and what were going to learn. As evening approached and the light faded we lost our visual contact with the whale and returned to the Point Sur to track the animal from the big boat. Using a powerful array of antennas, we positioned ourselves at the head of the Bay and listened for the whale. Without knowing when the tag would come off, we had to maintain contact with the whale. If, by chance, the whale stayed in the Bay, there was a good chance the tag could come off the whale while it was under sea ice and it would be lost. If it moved into the open water of the Gerlache Strait we could track it easier and hopefully recover it more easily.
At 0430, after nearly 19 hours, the whale swam out of Wilhelmina Bay, into the Gerlache Strait, and promptly shed the tag. The constant sounds of the VHF at the surface, floating with the invaluable data it just collected, was music to our ears. We quickly maneuvered the ship, found the tag and scooped it up with a net. Before long it was offloading its cargo of information. We sat, more than eager to start unlocking the mysteries and complexities of how these whale behave, as the information rolled in.
Our minds are now full of ideas and questions, and the hope that this deployment will open the door to help us and other researchers understand more about these whales that persist on the knife-edge in Antarctica, especially in the warming waters around the Antarctic Peninsula.