140. Bolle et al. (2011) did not find significant impacts at a cumulative SEL of 206 dB on sole larvae and suggested that the assumption of 100% mortality within a radius of 1000m around a piling site (used in the Appropriate Assessment of Dutch offshore windfarms) is too precautionary in the case of sole larvae. It was stated that the results should not be extrapolated to fish larvae in general, as inter-specific differences in vulnerability to sound exposure may occur. Furthermore, this study was focused on the potential lethal effects of sound exposure and not on any physiological, behavioural or morphological effects or on determining the likelihood of survival in the long term. The results do however, suggest that previous assumptions in relation to the lethal impact of noise on larvae and the injury criteria are likely to be over-precautionary and should be revised.
141. Taking the relatively small areas around each piling operation where larval mortality may potentially occur and the short term and intermittent nature of piling, the magnitude of the effect is considered to be low. The distribution of larvae of a given species extends over wide areas at a given time. Whilst larvae would not be able to flee the vicinity of piling, the probability and frequency of interaction with piling events is expected to be low. In this context, the small amount of larval mortality associated with piling in relation to the natural mortality rates during this life stage should be noted. Taking the above into account, larval stages are considered of medium sensitivity and instantaneous injury impact is therefore assessed to be of minor adverse significance.
Species of Limited Mobility- Gobies 142. As identified in site specific epibenthic surveys and IBTS data, sand gobies are expected to be present in the area of the East Anglia THREE site. Sand gobies have limited mobility and may therefore have limited capacity to escape areas impacted by piling noise. Given the short term, intermittent and localised nature of piling, however, the magnitude of the effect is considered to be low.
143. Sand gobies are prey for a number of species and are protected under the Bern Convention. They are abundant over wide areas of the North Sea therefore any noise effects would impact only a small proportion of the population. Furthermore, given the relatively short life cycle of this species (Teal et al. 2009) they are expected to recover quickly if subject to localised lethal or injury impacts associated with piling. Taking the above into account, they are considered to be receptors of medium sensitivity, the significance of the impact is assessed to be of minor adverse.
Species of Limited Mobility- Sandeels 144. Figure 11.56 depicts Sandeel grounds as defined by Jensen et al. (2011). As is apparent, these are extensive throughout the Southern and Central North Sea, and
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 11 Fish and Shellfish Page 59
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