Energetics of Foraging Decisions in Deep-Diving Toothed-Whales: Linking Individual Strategies to Population-Scale Processes in the Deep Sea

Objective

Foraging is the key energetic currency transfer system governing survival, reproduction, and population viability. Thus, individual foraging success scale directly to population dynamics. Yet in the deep sea, quantitative knowledge of predator-prey energetic transfer is almost entirely absent. D3EP-FINS addresses this gap by quantifying for the first time energetics of deep-sea foraging by large top predators. This is achieved by developing a stochastic dynamic programming model of Risso’s dolphins (Grampus griseus), deep-diving specialists on deep-sea squid. Existing frameworks quantify energetic trade-offs and scale findings to population-level effects but require concurrent data on predator and prey energetics, which are rarely available for deep-diving whales. As a result, these frameworks cannot yet accurately predict population-level consequences for deep-diving whales. I will use an exceptional dataset from the Azores, where Risso’s dolphin (Grampus griseus) foraging behaviour has been studied alongside prey distribution, density, and energy content, giving a unique holistic setting to study foraging decisions of a deep-diving predator. Fine-scale movement and acoustic data from biologging devices allow investigation of foraging consequences, while a comprehensive prey dataset, including environmental DNA prey community assessments, dietary DNA from faecal samples, acoustic monitoring, and calorific measurements, offers rare insight into prey fields in the deep sea. D3EP-FINS pursues three objectives: 1. quantify the energetics of foraging in deep-sea top predators, 2. scale individual outcomes to population-level processes, and 3. predict consequences of environmental variability and anthropogenic disturbance. The proposed project, D3EP-FINS, provides critical insight into predator-prey dynamics and delivers a framework to assess energetic impacts of foraging disruptions, with key implications for conservation of data-poor and elusive deep-diving whales.