PhD Defence – Sharks, rays and offshore wind farms

On Wednesday 15 January, at 2pm, Pierre LABOURGADE will defend his PhD addressing interactions between elasmobranchs and offshore wind farms using a multi-scale spatial approach. His thesis was carried out at France Energies Marines (Brest), as part of the FISHOWF project, under the supervision of Éric FEUNTEUN (MNHN), with the co-supervision of Lydie COUTURIER (FEM) and Thomas TRANCART (MNHN), as well as Jérôme BOURJEA (Ifremer), Mathieu WOILLEZ (Ifremer) and Jan REUBENS (VLIZ).

Watch the defence (connection link)

Abstract

Elasmobranchs (sharks and rays) play a crucial role in marine food webs, but their populations are globally declining and often overlooked in the face of anthropogenic disturbances. The rapid development of offshore wind farms (OWFs) raises questions about their impacts on these species. For example, on a large scale, the installation of an OWF may affect connectivity during species movements, while electromagnetic field emissions generated by submarine cables may cause behavioural changes within a few metres around the source. Acoustic telemetry appears as a relevant tool to address knowledge gaps on space use, occupation patterns and movements of free-swimming individuals within their natural environment and how those behaviours are influenced by anthropogenic activities. Multilateral passive acoustic telemetry was used in this thesis to monitor in situ the occupancy patterns of two benthic elasmobranch species, the small spotted dogfish Scyliorhinus canicula and the undulate ray Raja undulata, around an OWF export cable. The overall results provide valuable information as the first in situ study on the interactions of these species with the submarine cables of an OWF, which can serve as a reference. In this thesis, Pierre LABOURGADE also examined the occurrence and occupancy patterns of the small spotted dogfish at a larger spatial scale, across different habitat types within the first operational French OWFs. The results showed that the OWF did not appear to repulse tagged individuals, that displayed habitat fidelity with seasonal residency of individuals. The current study has provided new insights into key aspects of the ecology of benthic elasmobranchs and how they interact with OWF structures. This thesis underscores the relevance of using acoustic telemetry at multiple spatial scales and brings new perspectives to the study of effects of OWFs in natura on free-swimming elasmobranch.

Jury members

• Marie-Laure BEGOUT (Research Director, Ifremer UMR MARBEC, France), Rapporteur
• Fabrice DUPONCHELLE (Research Director, IRD UMR MARBEC, France), Rapporteur
• Benoit BERGES (Researcher, Wageningen Marine Research, Netherlands), Examiner
• Laura IBORRA (Researcher, RWE Renouvelables, France), Examiner
• Éric FEUNTEUN (Professor, MNHN, Station Marine de Dinard, UMR BOREA, France), Thesis Director
• Lydie COUTURIER (Researcher, France Energies Marines, France), Thesis co-director
• Thomas TRANCART (Researcher, MNHN, Station Marine de Dinard, UMR BOREA, France), Thesis co-director
• Jérôme BOURJEA (Researcher, Ifremer, UMR MARBEC, France), Thesis co-supervisor
• Mathieu WOILLEZ (Researcher, Ifremer, UMR DECOD, France), Thesis co-supervisor
• Jan REUBENS (Researcher, Flanders Marine Institute – VLIZ, Belgium), Thesis co-supervisor

Photo credit : Rémy Dubas / ECOCEAN