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90121 mm FL (weight not given) to sheet pile steel tube but with mechanical shaker-driven pistons driving in the Port of Anchorage. In this study, fish at either end. This chamber was used to study the were exposed to as many as 2,781 pile driving strikes effects of sound exposure on the lungs of mice at distances ranging from 1 to 50 m from the source. (Dalecki, 2002) as well as the effects of sonar expo- Acoustic monitoring during the tests measured peak sure on the vestibular system of guinea pigs. In both SPLs as high as 195 dB re 1 Pa and SELss values cases, it was demonstrated that the traveling wave as high as 166 dB 1 Pa2s, with SELcum as high as sound field to which the animals were exposed was 191 dB re 1 Pa2s. No mortalities were observed equivalent to a far-field scenario and that the response and no tissue damage was reported as late as 48 hrs of organs and tissues were comparable to studies done post-exposure. As in the case of the Ruggerone et al. in far-field conditions. (2008) study, the test fish in this study were not given the opportunity to fill their swim bladders prior to exposure. The results of this study are only applica- CHAPTER 2 METHODS ble to unacclimated (negatively buoyant) salmonids The sound exposure paradigms used in this for this reason. study were designed, in part, to test the validity of the "equal energy" hypothesis that has been widely Study Goal and Objectives cited for management of activities that generate impulsive sounds. In addition, the paradigm was The goals of this study were to assess the designed to obtain data necessary to derive a stress- effects of exposure to high-intensity pile driving response function. The equal energy hypothesis sounds on Chinook salmon physiology and to states that the risk of injury to fishes is a function of develop an understanding of the sound exposure(s) the SELcum, and there is no need to consider other that result in the onset of physiological impact on sound metrics, such as SELss and/or the number of fish. An additional goal was to provide quantitative strikes. In other words, the "equal energy" hypothe- data that can be used to define criterion levels for sis predicts that no matter how a SELcum value is tissue damage onset for use in design of pile driv- reached (e.g., a few strikes with higher energy per ing projects and in identifying options for protec- strike, many strikes with lower energy per strike), tion of animals. the effects on fishes would be the same. Initially, an additional goal was to measure the The methodology used in the experiments to test effects of exposure to sounds on hearing capabili- this hypothesis is documented in this section in ties. However, due to technical difficulties, it was agreed by the investigators, the NCHRP advisors, brief, with details provided in referenced Appen- and outside experts, that hearing measures would dices. Each aspect of the study is addressed: not be continued or included in this report (see Fish source and fish maintenance; Appendix H for details of those studies). The sound exposure device, including design and operation; and Barotrauma assessment and characterization. Previous Studies Using Similar Equipment In each case, details are provided for the meth- The original approach of designing a rigid tube ods and approaches used to conduct the study. for acoustical studies was an attempt to measure hearing thresholds of a fish in the laboratory with an ideal plane-wave sound field (Hawkins and Study Fish MacLennan, 1976). The Hawkins and MacLennan (1976) study used a steel tube 80 cm long with a This study used juvenile Chinook salmon with 13-cm wall thickness and 27-cm inner diameter fit- an average standard length of 103 mm 8.75 mm ted with a sound projector at each end. The hearing (standard deviation) and an average weight of 11.8 g thresholds of the plaice, Pleuronectes platessa, were 3.47 g (Figure 1). The Chinook salmon were pro- measured in terms of sound pressure and particle vided by Pacific Northwest National Laboratory motion. from the Priest Rapids Hatchery in Mattawa, Wash- A similar chamber was designed several decades ington. Additional details on study fish are found in later (Rogers and Lewis, 1999), again with a rigid Appendix F. 7