Current expansion of offshore industrial activities has led to concern about the impact of man-made sounds upon marine animals (Southall et al., 2007; Hastings, 2008; Popper and Hawkins, 2012, 2014). Offshore oil and gas exploration and developments, wind farm construction and operations, other renewable energy sources, dredging, construction activities, naval sonars, and increases in commercial shipping are all contributing to increased noise in the sea.
While most concerns have been focused on effects on marine mammals, similar issues arise with other marine life including fishes, turtles, and invertebrates. While the basic principles we discuss, however, are applicable to all marine groups, the focus of this paper will be on fishes since that is our particular area of research interest.
Many marine animals use sound during their everyday lives to track prey, avoid predators, navigate, and communicate with one another (e.g., Hawkins and Myrberg, 1983). And even species that do not communicate by sound use the acoustic scene (or soundscape) to learn about and exploit their environment (Fay and Popper, 2000). Thus, anything in the environment that interferes with the ability of a fish to detect and use sounds of biological relevance could have a substantial impact on fitness and survival.
A succession of reports and scientific papers has now emphasized the potential risks to marine animals from exposure to man-made sounds or noise (Southall et al., 2007; Popper and Hawkins, 2012, 2014; Popper et al., 2014). Increasingly, environmental assessments of the impact of offshore developments and other activities have been required to consider the effects of underwater noise.
An environmental assessment essentially evaluates the effects of underwater noise in terms of mortality or any physical injury, impairment to hearing, or behavioral disturbance it might cause to animals in the ocean. The assessment end points are typically aimed at determining whether there is a significant impact on populations of marine animals and on the wider ecosystem. Often a threshold for an adverse effect is sought, and this can lead to conclusions about the likely severity of any impact. This process, referred to as risk assessment, can subsequently be used to construct “what-if ” scenarios to evaluate methods for effective prevention, control, or mitigation of impacts, and to provide a reasoned basis for action to reduce risks.