No abstract

There is increasing concern about the effects of pile driving and other anthropogenic (human-generated) sound on fishes. Although there is a growing body of reports examining this issue, little of the work is found in the peer-reviewed literature. This review critically examines both the peer-reviewed and 'grey' literature, with the goal of determining what is known and not known about effects on fish. A companion piece provides an analysis of the available data and applies it to estimate noise exposure criteria for pile driving and other impulsive sounds. The critical literature review concludes that very little is known about effects of pile driving and other anthropogenic sounds on fishes, and that it is not yet possible to extrapolate from one experiment to other signal parameters of the same sound, to other types of sounds, to other effects, or to other species.

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Sound is an important means of communication in aquatic environments because it can be propagated rapidly (five times faster than in air) over great distances and it is not attenuated as quickly as other signals such as light or chemicals (Hawkins and Myrberg, 1983). Thus, it is not surprising that fishes and marine mammals make considerable use of sound for communication, for detection of predators and prey and for learning about their environment (Au and Nachtigall, 1997;Edds-Walton, 1997;Zelick et al., 1999;Fay and Popper, 2000).Within the past decade, there has developed an increased awareness that underwater anthropogenic (human-generated) sounds may be detrimental to marine organisms by masking the detection of biologically relevant signals and/or even damaging the exposed animals (NRC, 2000(NRC, , 2003. These sounds may be associated with shipping, dredging, drilling, seismic surveys, sonar, recreational boating and many other human-made sources. As a result of these human-generated sounds, ambient noise levels in the ocean are thought to be growing (NRC, 2003). Early estimates by Ross (1993) suggest a 10·dB increase from 1950 to 1975 alone or more than a doubling in noise level. This is likely to have risen further with increases in shipping and uses of other acoustic sources in parts of the oceans (NRC, 2003). Indeed, recent forecasts by the National Oceanographic and Atmospheric Administration's Marine Transportation System indicate that foreign oceanborne trade is expected to double by the year 2020 (US Department of Transportation, 1999), and this could result in even greater ocean noise levels in shipping lanes unless there are dramatic changes in ship acoustics.Substantial exposure of fish to acoustical stress is also found in many aquaculture facilities (Bart et al., 2001) that are important sources of food, ornamental species and stock enhancement of wild populations. While considerable effort has been made to optimize growth of aquaculture species by manipulating many environmental parameters such as temperature, food quality, photoperiod, water chemistry and stock density, little or no concern has been directed to determining the appropriate acoustic environment for optimal growth and development. Rearing conditions in aquaculture tanks can produce sound levels within the frequency range of fish hearing that are 20-50·dB higher than in natural habitats (Bart et al., 2001). The few studies that have examined the Fishes are often exposed to environmental sounds such as those associated with shipping, seismic experiments, sonar and/or aquaculture pump systems. While efforts have been made to document the effects of such anthropogenic (human-generated) sounds on marine mammals, the effects of excess noise on fishes are poorly understood. We examined the short-and long-term effects of increased ambient sound on the stress and hearing of goldfish (Carassius auratus; a hearing specialist). We reared fish under either quiet (110-125·dB re 1·µPa) or noisy (white noise, 160-170·dB re 1·µPa) conditions a...

Otoliths are of interest to investigators from several disciplines including systematics, auditory neuroscience, and fisheries. However, there is often very little sharing of information or ideas about otoliths across disciplines despite similarities in the questions raised by different groups of investigators. A major purpose of this paper is to present otolith-related questions common to all disciplines and then demonstrate that the issues are not only similar but also that more frequent interactions would be mutually beneficial. Because otoliths evolved as part of the inner ear to serve the senses of balance and hearing, we first discuss the basic structure of the ear. We then raise several questions that deal with the structure and patterns of otolith morphology and how changes in otoliths with fish age affect hearing and balance. More specifically, we ask about the significance of otolith size and how this might affect ear function; the growth of otoliths and how hearing and balance may or may not change with growth; the significance of different otolith shapes with respect to ear function; the functional significance of otoliths that do not contact the complete sensory epithelium; and why teleost fishes have otoliths and not the otoconia found in virtually all other extant vertebrates.

The literature on fish hearing has increased significantly since our last critical review in 1973. The purpose of the current paper is to review the more recent literature and to identify those questions that need to be asked to develop a fuller understanding of the auditory capabilities and processing mechanisms of fishes. We conclude that while our understanding of fish hearing has increased substantially in the past years, there are still major gaps in what we know. In particular, the comparative functional literature is extremely limited, and we do not yet know whether different species, and particularly hearing specialists as compared to hearing nonspecialists, have fundamentally different auditory capabilities and mechanisms.

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Marine petroleum exploration involves the repetitive use of high-energy noise sources, air-guns, that produce a short, sharp, low-frequency sound. Despite reports of behavioral responses of fishes and marine mammals to such noise, it is not known whether exposure to air-guns has the potential to damage the ears of aquatic vertebrates. It is shown here that the ears of fish exposed to an operating air-gun sustained extensive damage to their sensory epithelia that was apparent as ablated hair cells. The damage was regionally severe, with no evidence of repair or replacement of damaged sensory cells up to 58 days after air-gun exposure.