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Dotted Lines = SELcum = SELss + 10Log10(Num.Strikes) Black Lines = RWI = exp(-30.050 + 0.149*SELcum - 0.000171*Num.Strikes)-1 2200 1 2 3 4 5 6 7 8 9 10 1800 Number of Strikes 1400 1000 20 20 20 20 20 21 21 21 21 0 2 4 6 8 0 2 4 6 600 170 172 174 176 178 180 182 184 186 188 SELss Figure S-1 Treatment RWI and SELcum by SELss and number of strikes for all treatments. A contour plot of RWI (the darker curved lines labeled 1-10) illustrates value increases as SELss increase. The dashed lines represent the SELcum curves. The upper horizontal line indicates the 1,920 strike-line, and the bottom horizontal line indicates the 960 strike-line. The darker curved RWI linear contours are the result of testing at only 1,920 and 960 strikes. It is not known whether the functional relationship shown would persist if additional levels of strike numbers were tested. (Note: the two unlabeled curved lines in upper right corner of plots are 218 and 220 dB.) Potential Criterion CHAPTER 1 BACKGROUND Based on the study results and findings, an option Pile driving is becoming increasingly important is to use an RWI biological response criterion of 2, in the United States and throughout the world for which establishes a new biological response criterion construction projects both near shore and offshore, for barotrauma. The corresponding acceptable expo- and includes construction of bridges, docks, liquid sure bounds include impulsive sounds that are natural gas piers, and the like. Although such con- less than or equal to 179 dB re 1 Pa2s SELss for struction typically has been limited to relatively 1,920 strikes and less than or equal to 181 dB re shallow waters near shore and in rivers and streams, 1 Pa2 s SELss for 960 strikes, combined with a more recent pile driving efforts now include deeper SELcum of no more than 211 dB. These impulsive water offshore wind farm construction. Because of sound exposure criteria would allow up to two Mild the increase in pile driving, there is growing concern injuries and would not allow for a single Moderate that the sounds produced by pile driving activity injury. An RWI biological response criterion of 2 is have the potential to harm or kill fishes and/or result conservative, while it also raises the current interim in behavioral changes that could affect the survival exposure criteria to a higher level for impulsive of populations or even of species. sounds, which take into account more acoustic met- Despite this increased concern, a recent critical rics. These options are for juvenile Chinook salmon review of the literature detailing the known effects of an average standard length of 103 mm and mean of pile driving on fishes has revealed a significant weight of 11.8 grams. Application of these data to dearth of information (Popper and Hastings, 2009). other species could be done with care, but specific Most of the work on effects of pile driving has sig- options for other species are beyond the bounds of nificant experimental problems that may include this study. experimental design, inadequate use of controls, 4