Meeting Abstract
Marine mammals must function effectively during extended periods without access to atmospheric oxygen during behaviors such as migration or foraging. How efficiently these animals swim directly affects oxygen management and determines both dive duration and activity levels that can be maintained. Therefore, an understanding of energetic cost during these behaviors is critical for determining the physiological (and thus behavioral) envelope of diving animals, and the consequences of anthropogenic stressors on their fitness. However, direct measurements of energetic cost or external forces (thrust for propulsion or drag on the body) are challenging for large swimming animals. Recent work has been conducted to directly measure the thrust created by swimming bottlenose dolphins using particle image velocimetry. But, these studies are limited by camera-based kinematic data collection in controlled environments that restrict data collection to a few fluke strokes of straight-line swimming, and are not practical for use with wild animals. As such, energetic expenditures of free-swimming whales and dolphins can be estimated only by using proxies such as heart rate, respiration rate or body acceleration. Further, experimental validation of these proxies has been limited. This work seeks to create the knowledge necessary to estimate mechanical work, a key contributor to the overall metabolic cost of free-swimming cetaceans. Here we present new estimation algorithms to combine data from multi-sensor tags and models of swimming kinematics to estimate per-stroke work and power during swimming. These estimates were evaluated in a controlled experimental environment with managed animals during controlled swimming tasks.
