There are >31,000 species of extant fishes (www.fishbase.org), many of which are marine fishes. Marine fishes face threats from many different human activities, including overfishing, habitat degradation and loss, bycatch, and and sound produced as a consequence of human activities. Although much of the attention on the effects of anthropogenic (human-generated) sounds on marine animals has focused on marine mammals, the same concerns are being raised about the effects of sound on fishes. However, much less is currently known about the effects of underwater sound on fishes than on marine mammals.
There are many types of marine habitats, such as nearshore, offshore, and deep ocean, each with a different soundscape. We know very little about the sound characteristics of some habitats. One habitat that has been fairly well studied is coral reefs. These are noisy environments because of abundant naturally produced sounds like winds, waves, and sounds produced by a large number of inhabitants (for more information see What are common underwater sounds?). An understanding of the natural soundscape is needed in order to determine the impact of sounds contributed by human activities.
Sources of anthropogenic sound are extensive and include any kind of boating or shipping, seismic exploration devices (such as airguns), construction activities (such as pile driving), and active sonar (used by the by the shipping industry, commercial and recreational fisheries, the military, and the oceanographic research community). Potential effects on fish from intense anthropogenic sounds, such as those associated with airguns and pile driving, could include: death, tissue damage, or injuries that might not directly result in death but may make a fish more vulnerable until healing takes place; temporary hearing loss; masking of biologically relevant sounds; behavioral changes, such as moving towards or away from a sound source or leaving a feeding or breeding site; and increased stress. Longer lasting sounds, such as those associated with shipping, cause a general increase in background noise in some locations. This increase in background noise may result in the masking of biologically important sounds that are critical for fish behavior. It is far more difficult for a fish to escape from general increases in background noise as opposed to brief and/or localized sounds that are often moving (e.g. sonar) or that fish may swim by (e.g. pile driving). These effects require much more research, although masking by background sound has been demonstrated in several fish studies.
A number of factors potentially affect the impact of sounds on marine animals. These include the sound level, its frequency, and other characteristics of the soundsuch as duration and onset time (how fast the sound gets turned on); the hearing sensitivity, age, sex, and behavior of the animals; and the environmental conditions under which the animals experience the sound.
It is difficult and expensive to study the behavior of marine animals. Although it is likely that increases in underwater sound are likely to affect fishes in some way(s), much more research on a wide range of fish species and different sound sources is necessary in order to fully understand the extent of these effects. The effect of sound on different life history stages of fish and the relative effects of sound on different species also need to be considered. Fish eggs that are stationary in nests, for example, could be exposed to sound that may affect development and survival. It is also imperative that studies on the behavioral responses of fish to anthropogenic sound also need to be conducted in their natural habitats in order to understand “wild” responses of fish to human-generated sound.
The following sections discuss effects that have been discovered using rigorous scientific methods and are published in the scientific literature.
- Popper, A.N, and Hastings, M.C. 2009, "The effects of human-generated sound on fish." Integrative Zoology. 4, 43-52.
- Hawkins A.D. and Popper, A.N. 2014, "Assessing the impacts of underwater sounds on fishes and other forms of marine life." Acoustics Today. 10(2):30–41.
- Hawkins, A. D., Pembroke, A., and Popper, A. N. 2014, "Information gaps in understanding the effects of noise on fishes and invertebrates." Reviews in Fish Biology and Fisheries. DOI 10.1007/s11160-014-9369-3.
- Popper, A.N., Hawkins, A.D., Fay, R.R., Mann, D., Bartol, S., Carlson, T., Coombs, S., Ellison, W.T., Gentry, R., Halvorsen, M.B., Løkkeborg, S., Rogers, P., Southall, B.L., Zeddies, D., Tavolga, W.N. 2014, "Sound Exposure Guidelines for Fishes and Sea Turtles: A Technical Report prepared by ANSI-Accredited Standards Committee S3/SC1 and registered with ANSI." ASA S3/SC1.4 TR-2014. Springer and ASA Press, Cham, Switzerland.
- Popper A.N., and Hastings, M.C. 2009, "The effects of anthropogenic sources of sounds on fishes." Journal of Fish Biology. 25, 455-489.
- Hutchings, J. A. & Reynolds, J. D. 2004, "Marine fish population collapses: consequences for recovery and extinction risk." Bioscience. 54: 297–309.
- Slabbekoorn, H., Bouton, N., van Opzeeland, I., Coers, A., ten Cate, C. and Popper, A. N. 2010, "A noisy spring: the impact of globally rising underwater sound levels on fish." Trends in Ecology and Evolution. 25, 419-427.