This page contains a Flash digital edition of a book.
over 8 grams and 213dB re 1 μPa2·s for fish over 200 grams. The FHWG dual criteria were also included in a technical guidance document for assessing the effects of pile driving on fish, issued by the California Department for Transportation (Oestman et al. 2009). Whilst the FHWG dual criteria for fish injury are perhaps the most widely adopted criteria for fish, it should be noted that the findings are based on a limited number of studies and substantial variation between fish species, size, age and sex might be expected, in addition to variability due to the sound source, the environment and the activity of the fish being considered. New injury criteria for fish are expected from an Acoustical Society of American standards working group created for this reason (Fay and Popper 2006) and more recent publications by Halvorsen et al. (2011 and 2012) question the use of the equal energy hypothesis. The study by Halvorsen et al. (2011) proposes the use of a 1 to 10 response weighted index (RWI) based on the level of physiological significance of damage, where an RWI of 2 or less does not lead to physiological effects that reduce either the immediate or long-term performance and energetics. The cumulative SEL, or SEL dose, established in the study using 2,000 pulses which resulted in a RWI of 2, considered to be sub- onset of injury, was 211dB re 1 μPa2·s. These findings are based on juvenile Chinook salmon Oncorhynchus tshawytscha with a mean weight of 11.8 grams and generally result in a higher SEL dose threshold than those proposed by the FHWG, except for the case of fish over 200 grams in weight.


74. A recent study by IMARES (Bolle et al. 2011; 2012) which exposed common sole larvae to piling noise observed no statistically significant effect on their survival rates for a piling sequence which resulted in a SEL dose of 206dB re 1 μPa2·s. Although the results should not be extrapolated to all species, the study does indicate that the injury criteria for small fish (less than 2 grams) of 183dB re 1 μPa2·s SEL dose proposed by the FHWG may not be applicable for fish larvae.


9.5.4.2 Behaviour (Fish) 75.


Studies on the behavioural response of fish to underwater low frequency impulsive sounds are limited and currently, no international criteria exist for assessing behavioural impact of sound on fish. Reviews of the effects of sound on fish have been carried out by Hastings and Popper (2005), with a particular emphasis on pile- driving, and a review focussed on the effects on fish of seismic survey sources was carried out by Worcester (2006). When comparing studies, care should be taken to ensure the reported metrics and the type of source are comparable.


76.


There is clear evidence that the behaviour of free swimming fish is influenced by sound as a fall in fish catch rates has been observed following seismic surveying (Engås et al. 1996; Webb et al. 2008; Løkkeborg et al. 2010). However, the type of


Preliminary Environmental Information May 2014


East Anglia THREE Offshore Windfarm Appendix 9.1 Underwater Noise Modelling 27


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150