The Scale of the Whale: Using Video-tag Data to Determine Sea Ice Utilization of Antarctic Minke Whale (Balaenoptera Bonaerensis)

Advances in bio-logging technology have opened doors for new sensors and tools to aid in the remote study of wildlife. These tools allow researchers access to previously unobservable behavioral states and movement patterns of marine animals. In order to relate behaviors to environmental variables, features must be evaluated at scales relevant to the individual animal or behavior. Historically, remotely-sensed environmental data (collected via satellites) lack the spatial or temporal resolution to adequately link with individual animal behaviors or bouts. The aim of this study is to establish a new method for remotely and continuously quantifying Sea Ice Concentration (SIC) at a scale relevant to an individual whale. Motion-sensing and video-recording suction cup tags were deployed on 30 Antarctic minke whales in February and March of 2018 and 2019 around the Antarctic Peninsula. For a typical dive in each tag position, observable surface area (m²) upon ascent was calculated from depth, tag pitch and camera angle of view. SIC was evaluated by three independent observers at the beginning and end of each dive as a % value fitting one of six bins (0%, 1-20%, 21-40%, 41-60%, 61-80%, 81-100%). For each observation SIC was determined as the median value between the observers. Initial results from 6 tags show that the animals in this study spent 52% of their time in open water, and only 15% of their time in water with SIC greater than 20%. Over time, we find significant variation in observed SIC, indicating that Antarctic minke occupy an extremely dynamic environment. As part of on an integrated multisensor platform, our ability to quantify SIC continuously at the scale of the animal will improve upon current remote sensing methods to understand the link between animal behavior and dynamic environmental variables.