This environmental impact assessment for Kriegers flak ... - Vattenfall

126 CONSEQUENSES OF THE WIND FARM
seabed conditions (Wahlberg and Westerberg, 2004).
Theoretically, the noise from wind turbines could
frighten Þ sh, but only within a distance of maximum
4 metres and only at high wind speeds, 13 m/s (Wahlberg
and Westerberg, 2004).
Studies show that Þ sh learn to associate certain
noise with a certain occurrence. This could result in
that Þ sh associate noise from wind turbines with a nondangerous
structure that does not frighten them.
Noise measurements from the wind farm at Utgrunden
show that the noise emitted by the turbines
not even frightens the Þ sh away at a distance of 1 metre
from the turbines. This could indicate that Þ sh associate
the noise from wind turbines with something that is
not dangerous.
It may further be assumed that the continuity of
noise is a determining factor for the reactions of Þ sh.
Westerbergs investigations of Þ sh behaviour near
bridges with car and train trafÞ c showed that Þ sh did
not to any great extent react to the more or less continuous
trafÞ c, but that shoal of Þ sh could make vertical
movement changes at sudden noise emissions, such
as when a train passed the bridge. This would indicate
that the continuous noise from wind turbines will not
have a signiÞ cant impact on Þ sh. However, no certain
conclusions can be drawn as the study was limited in
scope.
For many Þ sh, noise signals are important in order
to localise each other during spawning and signal readiness
for mating. Noise and vibrations could therefore
inß uence the suitability of an area for spawning. Studies
show that noise from wind turbines may inß uence
signalling of Þ sh at a distance of several kilometres
but the degree of importance of such inß uence is not
known (Wahlberg and Westerberg, 2004).
Studies have shown that if Þ sh continuously are subjected
to high noise levels, damage to the inner ear can
follow (Hastings et al., 1996, McCauley et al., 2003).
There is, however, nothing that indicates that noise
from wind turbines may, temporarily or permanently,
damage the hearing of Þ sh (Wahlberg and Westerberg,
2003).
The studies that have been made on the impact of
noise on Þ sh have generally been conducted on single
turbines and smaller structures. The results cannot,
therefore, easily be transferred to large wind farms. It
should also be noted that the knowledge of the impact
on roe and juvenile Þ sh is very small. Following a
review of the studies, Wahlberg and Westerberg (2004)
conclude that juvenile Þ sh are at least as sensitive as
grown species while roe is considered less sensitive.
A careful judgement would however be that noise
from wind turbines does not have any important negative
impact on Þ sh. The fact that large numbers of Þ sh
have been registered at Horns Rev (Hvidt et al., 2004)
supports this theory.
The effect of noise and vibrations on Þ sh will be
studied closely during a control programme following
the construction of the wind farm. The control programme
is described in Attachment 19.10.1.
The dismantling phase
Noise during the dismantling phase may temporarily
frighten the Þ sh away. Noise that causes damage
to the hearing of Þ sh is not very likely, but cannot be
excluded.
b) Light, shadows and refl exes
During the operational phase, light is generated from
the ß oodlights on the turbines. Light is known to attract
Þ sh but apart from a possible collision risk, Þ xed
light points are not considered to cause any negative
impact.
During the operational phase, the towers and the
blades cause shadows that could have an impact.
During the construction and dismantling phases, the
shadows are temporary and during these periods, the
impact is limited.
Fixed shadows, such as behind the towers, attracts
Þ sh and is not considered to have a negative impact.
Fast movements that are mirrored on the water surface,
could on the other hand cause unrest. The blades,
sweeping over a large area, cause a ß uctuating shadow
on the water surface. Many organisms react by escaping
or by carefulness in similar situations. Among
anglers and scientists, it is considered common knowledge
that Þ sh react by escaping or seeking protection
when a shadow passes over them. The reason is probably
a protective measure so as not to become feed for
praying birds. Whether the Þ sh can get used to these
intermittent shadows has not yet been studied, but it is
regarded as likely that Þ sh get accustomed to it.
It should be noted that the light penetration in the
Baltic Sea stops at a depth of 20 – 25 metres, and it is