Redefining optimal foraging paradigms in air-breathing divers

Recently published in Science Advances, our team integrated ecological and physiological approaches to test long-standing theoretical models of optimal foraging. In order to exploit a patchy resource like krill in the marine environment, rorqual whales such as blue whales must exhibit behavioral plasticity to maximize foraging efficiency. Air breathing divers must also balance the trade-offs of oxygen use versus energy gain when determining how long a dive should last during foraging. Technological advances in our ability to measure the underwater feeding performance of marine predators have allowed for great insights in top predator foraging ecology, but rarely is this combined with quantitative measures of prey. We used data from 55 high-resolution suction cup tag deployments to quantify feeding rates and energy budgets as a function of prey density per lunge. In our study, we falsified and redefined the paradigm put forth in previous analyses by showing how a top predator switches from minimizing oxygen consumption to maximizing energy gain as a direct function of prey patch density and depth for the first time in the wild. Without advanced anatomical specializations for extreme engulfment capacity and the ability to exploit high-density prey patches, we posit that baleen whales could not have evolved nor maintain such large body sizes. Once thought of as indiscriminate filer feeders, our study shows that blue whales can adapt to prey field conditions on a dive-by-dive basis to exploit the highest quality prey patches and optimize multiple energetic currencies associated with diving and feeding. The results of our study was featured in several news media outlets including NPR’s Science Friday, Washington Post, San Francisco Chronicle, and Gizmodo.