PhD Defence: Jacopo di Clemente

Thesis title: How whales feed: a case study on inshore South African Bryde’s whales (Balaenoptera edeni brydei) - Towards understanding non-migratory whales

Supervisor: Associate Professor Elodie Floriane Mandel-Briefer, Department of Biology, University of Copenhagen
Co-Supervisor: Professor Jacob Nabe-Nielsen, Department of Ecoscience, Aarhus University

Assessment committee
Michael Poulsen, (chair), Department of Biology, University of Copenhagen
Kylie Owen, University of Tasmania, Australia
Takashi Iwata, Kobe University, Japan

Abstract
Understanding how whales feed allows for more targeted conservation strategies. In this thesis, I use inshore South African Bryde’s whales (Balaenoptera edeni brydei) as a case study to address the importance of understanding the foraging ecology of non-migratory rorquals (Balaenopteridae). Narrowing down from a pivotal study which shows that baleen whale prey consumption is up to three times higher than what hadpreviously been estimated without direct field measures — and thus, so is their role in nutrient cycling — I put this poorly known species in context with what is known nowadays about how whales forage. Bryde’s whales feed in different ways across different ecosystems, but no previous study on foraging kinematics exists for inshore South African Bryde’s whales. I present two previously undescribed feedingbehaviours for this population: the ability of switching among three different attack modes when lunging towards the prey at different depths, and the abrupt interruption the feeding operation at the point of maximum speed — introducing three possible scenarios for which such behaviour could happen. Digging in the same dataset, I explain how chasing prey along the seafloor at high-speed puts foraging whales at risk of entanglement in fishery gear. Overall, the findings of this thesis show 1) the presence of intra-population foraging flexibility in Bryde’s whales; 2) the potential decision of interrupting foraging according to the optimal foraging theory; 3) the impact of human activities on the fine scale feeding manoeuvres of whales. In an ecological context, this PhD thesis raises the question whether investigating on foraging is the key to figure out why some populations of whales do not migrate between feeding and breeding grounds — like firmly believed decades ago.

Zoom: https://ucph-ku.zoom.us/j/61861371226?pwd=pO9UwLwmSanb5WI3z2aIu3AUhbB6zq.1