Resource Management Issues: Acoustic Impacts

Overview of the issue
A number of studies document impacts to living marine resources, including behavioral changes and physical effects due to exposure to anthropogenic noise and pressure waves in the marine environment. Anthropogenic sources of noise include large commercial shipping traffic such as container ships, freighters, barges and tankers, recreational and commercial boats, military low frequency testing, research activities and aerial overflights.

Marine mammals have been observed to deviate from their migration paths to avoid noise, or interrupt their communications in response to elevated noise levels. Certain anthropogenic noise is thought to mask sounds used for mating, feeding and avoiding predators. Responses vary depending on the acoustic frequency, decibel level, proximity to the source and other species-specific sensitivity factors. Concern about the cumulative impacts of noise from a variety of sources has grown as the ocean has become noisier in past half-century. However, long-term cumulative impacts are uncertain and range from minimal impacts in some situations to behavioral alterations to possible physiological or physical damage to hearing, to stranding events.

How is the Sanctuary involved?
The Sanctuary has been involved in evaluating and requesting limits or alterations of specific proposals to use acoustic devices in the region, such as the Navy’s Low-Frequency Array proposal, but has not addressed the overall issue of cumulative noise impacts. An assessment of the distribution of deep-diving whales in the sanctuary has been compiled to assist in evaluating potential impacts from acoustic disturbances