Many marine resource managers work with environmental protection agencies overseeing the impact of development on the marine environment and formulating procedures for minimizing this impact. There is a need to increase understanding the degree to which anthropogenic activities may be changing the underwater soundscape, how these changes may potentially impact marine animals, and what action can be taken to mitigate these potential impacts. In accordance with the Marine Mammal Protection Act (MMPA), marine mammals cannot be hunted, harassed, captured, or killed. Individuals must apply for a permit in order to conduct research and/or other activities that may impact marine mammals. Incidental Harassment Authorizations (IHAs) or Letters of Authorization (LOA) may be issued to groups incidentally “taking” small numbers of marine mammals and/or casing a “negligible impact”. Most IHAs and LOAs have involved the incidental harassment of marine mammals by noise (airguns, ships and aircraft, high energy sonars, and explosive detonations). The National Oceanic and Atmospheric Administration (NOAA) is developing science-based acoustic guidelines for assessing the effects of anthropogenic sound on marine mammals. This will help guide the permit process. Draft guidelines are also being considered by the International Maritime Organization (IMO) to reduce underwater noise from commercial ships, giving special consideration to propulsion, hull design, onboard machinery, and operational modifications.
Acoustic devices can be used to reduce risk and decrease potential human impacts on marine animals. For example, passive listening systems called Marine Autonomous Recording Units (MARUs), or “pop-up” buoys, have been deployed along the Atlantic coast to continuously monitor for the presence of cetacean species such as the critically endangered North Atlantic right whale. Scientists are gathering acoustic data on the seasonal occurrence and distribution of endangered right whales in coastal waters to reduce the risk of ship strike. Regulations have been passed to implement speed restrictions in specific locations along the U.S. east coast, and shipping lanes have been shifted to reduce the risk of collision between large ships and whales. Real-time automatic-detection buoys are an acoustic tool used to monitor right whales off the coast of Massachusetts. Ten auto-detection buoys have been deployed between the Port of Boston’s inbound and outbound shipping lanes. The buoys can detect right whale vocalizations within 5 nautical miles, and information on which buoys detect whale vocalizations are re-transmitted to vessels. Captains, other mariners, and the general public can also access the real-time information from the “Right Whale Listening Network” . Time from detection at the buoy to posting on the website can be as short as 20 minutes.