Application of a multibeam echosounder to document changes in animal movement and behaviour around a tidal turbine structure

Benjamin Williamson, Philippe Blondel, Laura Williamson, Beth Scott

Research output: Contribution to journalArticlepeer-review

Abstract

Changes in animal movement and behaviour at fine scales (tens of metres) in immediate proximity to tidal stream turbine structures are largely unknown and have implications for risks of animal collision with turbine blades. This study used upward-facing multibeam echosounder data to detect and track
animal movement comprising fish, diving seabirds and marine mammals. Measurements over springneap tidal cycles at a turbine structure (no blades present) are compared to a neighbouring reference area with no structure and comparable conditions, with measurements consecutive in time to
maximise comparability.
The majority of tracked animals (93.4% around turbine structure and 99.1% without turbine structure) were observed swimming against the flow, with 87.5% and 97.8%, respectively, making ground and showing capability of manoeuvring in tidal stream flow speeds. Track tortuosity increased around the turbine structure compared to the reference site, particularly in the wake and at low flow speeds, indicating animal station-holding or milling behaviour. These data also evidence the benefits of multibeam echosounders to measure animal movement through larger measurement volumes rather than relying on single-beam echosounders to measure animal presence alone, including to avoid large
biases overestimating the size of schools swimming against the flow measured by time-in-beam.
Original languageEnglish
Number of pages25
JournalICES Journal of Marine Science
Publication statusAcceptance date - 12 Jan 2021

Keywords

  • Marine Renewable Energy
  • environmental monitoring
  • acoustic mapping
  • Multibeam echosounder
  • target tracking
  • tidal stream turbines
  • fish behaviour

ASJC Scopus subject areas

  • Acoustics and Ultrasonics
  • Ocean Engineering
  • Environmental Science (miscellaneous)

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