Regional-scale patterns in harbour porpoise occupancy of tidal stream environments

James J. Waggitt*, Holly K. Dunn, Peter G.H. Evans, Jan Geert Hiddink, Laura J. Holmes, Emma Keen, Ben D. Murcott, Marco Piano, P. E. Robins, Beth E. Scott, Jenny Whitmore, Gemma Veneruso

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


As harbour porpoises Phocoena phocoena are abundant within tidal stream environments, mitigating population-level impacts from tidal stream energy extraction is considered a conservation priority. An understanding of their spatial and temporal occupancy of these habitats at a regional-scale will help steer installations towards locations which maximize energy returns but reduce the potential for interactions with populations. This study quantifies and compares relationships between the presence of harbour porpoise and several hydrodynamic characteristics across four tidal stream environments in Anglesey, UK - a region that has been earmarked for extensive industrial development. Within sites (0.57-1.13 km 2), encounters with animals were concentrated in small areas (<200 m 2) and increased during certain tidal states (ebb vs. flood). In sites showing relatively high maximum current speeds (2.67-2.87 ms '1), encounters were strongly associated with the emergence of shear-lines. In sites with relatively low maximum current speeds (1.70-2.08 ms '1), encounters were more associated with areas of shallow water during peak current speeds. The overall probability of encounters was higher in low current sites. It is suggested that the likelihood of interactions could be reduced by restricting developments to sites with high maximum current speeds (>2.5 ms '1), and placing turbines in areas of laminar currents therein. This study shows that a combination of local and regional hydrodynamic characteristics can partially explain variations in occupancy patterns across tidal-stream environments. However, it was found that such hydrodynamic characteristics could not comprehensively explain these occupancy patterns. Further studies into the biophysical mechanisms creating foraging opportunities within these habitats are needed to identify alternative explanatory variables that may have universal applications.

Original languageEnglish
Pages (from-to)701-710
Number of pages10
JournalICES Journal of Marine Science
Issue number2
Early online date31 Aug 2017
Publication statusPublished - 31 Mar 2018

Bibliographical note

J.J Waggitt, P.G.H. Evans, and J.G. Hiddink are supported through the Marine Ecosystems Research Programme (MERP: NE/L003201/1) which is funded by NERC/DEFRA. M. Piano, P.E. Robins, J. Whitmore, and G. Veneruso are supported through the Sustainable Expansion of the Applied Coastal and Marine Sectors (SEACAMS2) research project (Grant Number: 80366) part funded by the European Regional Development Fund (ERDF) through the Welsh European Funding Office (WEFO) and also the Higher Education Funding Council for Wales (HEFCW). Simulation models were made possible by High Performance Computing (HPC) Wales (a collaboration between Welsh Universities, the Welsh Government and Fujitsu), the British Oceanographic Data Centre (BODC), the UK Hydrographic Office (UKHO), and the EDINA Marine Digimap Service. We wish to thank three anonymous reviewers and Kees Camphuysen for their constructive comments on earlier versions of this article.


  • cetacean
  • environmental impact assessment
  • foraging ecology
  • hydrodynamic model
  • marine renewable energy installations
  • marine spatial planning
  • shore-based surveys


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