For 275kV (separated) cables, distance would be slightly further
Table 9.3 Elasmobranch Avoidance Zone Distances Expected for East AngliaTHREE DC Cables Assuming Different Cable Burial Depths Burial Depth (m)
Avoidance Zone Distance from Cable 320kV
Bundled None 0.5 1 Tens of cm 0 0 Separated 1m 0.5m 0 For 600kV cables, distance would be slightly further 82. 83.
Significant avoidance reactions by elasmobranchs associated with EMFs from the proposed East Anglia THREE cables are therefore not expected to occur.
Attraction behaviour has been assessed through a number of studies but results have been inconclusive. Laboratory behavioural studies have demonstrated both AC and DC artificial electric fields stimulating feeding responses in elasmobranchs (Kalmijn 1982; Tricas & Sisneros 2004; Kimber et al. 2011). Recent work using lesser spotted dogfish (Scyliorhinus canicula) suggests that despite the ability to distinguish certain artificial E fields (strong versus weak; DC versus AC), sharks seemed either unable to distinguish, or showed no preference between similar strength, anthropogenic (dipole) and natural (live crab) DC E fields (Kimber et al. 2011).
84.
Experiments by Gill et al. (2009) provided the first evidence of electrically sensitive fish response to AC EMF emissions from sub-sea, electricity cables of the type used by the offshore renewable energy industry. This research found lesser spotted dogfish were more likely to be found within the zone of EMF emissions, and some thornback rays showed increased movement around the cable when the cable was switched on. Responses were, however, unpredictable and did not always occur, appearing to be species dependent and individual specific.
85.
Information gathered as part of the monitoring programme at the Burbo Bank offshore windfarm, suggested that certain elasmobranch species feed inside the windfarm and demonstrated that they are not excluded during periods of low power
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 9 Underwater Noise Page 20
500kV Bundled 0.5m 0 0 Separated 1-2m 0.5-1.5m 1m
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