In FEAST, we combined in a novel manner, the use of acceleration and acoustic data (passive and active acoustic) to quantify the links between pinnipeds foraging decisions and energetics with 3-D prey distribution using two species of coastal seals : the harbour and Weddell seals as highly relevant model species. Firstly, harbour seals target small fish (of commercial interest) in the shallow, temperate waters of Denmark generating almost inevitable interactions with human activities. We can also access harbour seal both in the wild and in captivity allowing for critical validation of both ecological and methodological assumptions before applying them to wild conspecifics and other species. In contrast, Weddell seals target bigger prey in colder, deeper water in an extreme but pristine environment, Antarctica. This allows for a unique comparison of niche specific foraging strategies among pinnipeds in two contrasting environments.
The originality and innovative aspects of FEAST lied at the intersection of bioacoustics, cutting edge engineering tools, signal processing, ecology and physiology to determine foraging optimization in free-ranging wild animals and how it can, ultimately, impact their individual fitness. In accomplishing FEAST objectives, I provide unprecedented tools, datasets and results to further understand the ecology of pinnipeds to ultimately address data gaps in assessing the potential impact of human activities and environmental changes on coastal marine mammals. This will be directly relevant to several of the objectives aimed by the European Commission’s Marine Strategy Framework Directive.
These are the objectives we addressed in FEAST:
WP1b: Quantify harbour seals’ fine scale foraging activity and associated energetic budgets to investigate how they optimize resource acquisition.
WP2b: Estimate prey type and field densities using active acoustic and D-Tags to simultaneously record seals’ foraging behaviour as well as direct information on the quality of the prey patch encountered.
WP3b: Estimate the body condition of wild seals, which is an important determinant of ecological fitness, from aerial images acquired from unmanned vehicles.
Research methodology and approach: To address these WPs, FEAST required the concomitant acquisition of the horizontal (GPS track) and vertical movements (dive profiles and 3D acceleration) as well as passive and active acoustics of the seals. Passive acoustic allows to record sounds associated with the surroundings of the seals but also provides access to physiological inferences, such as breathing sounds. Active acoustic allows getting information on objects that are in front of the seals, such as the prey they target. To do so, I took advantage of the latest development of D-Tags and sonar tags – size reduction, extended battery life, combination of movement sensors (i.e. GPS, magnetometer and accelerometer) – that were deployed on harbour and Weddell seals. Finally, recent advances in unmanned aerial vehicle (UAV) technology, and its increased accessibility have made UAVs an attractive tool for wildlife research and monitoring. UAVs offer a safe and inexpensive tool to collect data from individuals (i.e. behaviour and morphometric)
