Review of Cabling Techniques and Environmental Effects Applicable

Review of Cabling Techniques and Environmental Effects Applicable to the Offshore Wind
Farm Industry – Technical Report
level. The main potential impact is the disruption of the sensory cues for feeding
in benthic dwellers in and around the wind farm area. This is general for all
species of benthic dwelling elasmobranchii that feed diurnally and nocturnally.
EMF could have two possible effects on the behaviour of elasmobranchii. Firstly,
resident elasmobranchii could be deterred from feeding in and around the area
within the wind farm footprint and where cables are buried. The second impact
could be one of attraction of elasmobranchii to the footprint of the wind farm
potentially causing an unnatural clustering effect in the area.
There are, therefore, potentially significant effects on fisheries interests but to
date there has been no evidence to indicate the likelihood and/or magnitude of
these. The research undertaken by COWRIE, under laboratory conditions only has
been insufficient to determine the precise extent of detection for many marine
species; the behavioural response within the zone of detection and therefore the
likely impacts on fisheries resources due to EMF from sub-sea cables (COWRIE
2005).
For the Thanet Offshore Wind Farm site, English Nature stated that (given current
levels of ecological understanding) there will not be a significant impact to the
populations of elasmobranchii that are resident within the wind farm footprint
and cable export route but English Nature’s advice is provided in the light of
current information that is available (English Nature, 2006).
Additional research work on electromagnetic field effects is due to be carried out
under the auspices of COWRIE, which will entail “in the field” research. It is likely
therefore that developers will be asked to commit to take on board the most up
to date information on electromagnetic field effects, thereby making necessary
and reasonable adaptations during the construction, operation and monitoring
of wind farm developments.
5.4.2 MITIGATION MEASURES
In terms of the natural fish resource, general mitigation measures should seek
to do the following:
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Avoid spawning and nursery habitats. Such information should be available
from published sources or previous surveys. If this is not available then a
series of dedicated surveys should be commissioned as part of the wider EIA,
in discussions with Cefas;
Avoid sensitive spawning times for substrate spawning species where
possible (exact periods will be site specific and require evidence);
Impacts from noise may be mitigated by timing construction to avoid sensitive
feeding, spawning and nursery area/times of the year;