Marine Mammals: Underwater Noise

Hawaiian monk seal swimming near coral reef
Hawaiian monk seal, Monachus schauinslandi. (NOAA Photo Library)

The ocean has always been filled with sound from natural sources such as storms, earthquakes, and animals.  Recently, however, levels of underwater noise introduced from human activities (e.g., ships, sonar, and drilling) have increased – in some instances significantly.  The increasing anthropogenic noise levels can negatively affect marine animals and their ecosystems in complex ways including through acute, chronic, and cumulative effects. These effects are not surprising given that many marine animals and ecosystems rely on sound in a number of ways important to their survival such as communication, detecting predators and prey, and navigation. All ocean noise does not have the same impact, however since sources of ocean noise vary in many ways including how loud they are (intensity, measured in decibels), how long they last (fractions of a second to continuous), and their pitch or tone (frequency, measured in hertz).

NOAA is taking a multi-faceted approach to better understand the adverse physical and behavioral effects, including the ability to communicate, on species from exposure to certain noise and to ensure it fulfills its various legal obligations to protect aquatic animals and their habitats.  In September 2016, NOAA released its Ocean Noise Strategy Roadmap, which details an agency-wide strategy for addressing ocean noise over the next ten years. Rather than prescribing program-level actions, the Strategy summarizes essential steps that could be taken across the agency to achieve the Strategy’s goals. The Strategy has four goals:

  1. SCIENCE: NOAA and federal partners are filling shared critical knowledge gaps and building understanding of noise impacts over ecologically-relevant scales

  2. MANAGEMENT: NOAA’s actions are integrated across the agency and minimizing the acute, chronic, and cumulative effects of noise on marine species and their habitat

  3. DECISION SUPPORT TOOLS: NOAA is developing publically available tools for assessment, planning, and mitigation of noise-making activities over ecologically-relevant scales

  4. OUTREACH: NOAA is educating the public on noise impacts, engaging with stakeholders & coordinating with related efforts internationally

A number of international and regional bodies, international coalitions, and industry coalitions also have taken action to address anthropogenic ocean noise.  For example, in 2014 the International Maritime Organization (IMO), a specialized agency of the UN responsible for measures to improve the safety and security of international shipping and to prevent pollution from ships, approved the Guidelines for the Reduction of Underwater Noise from Shipping. These Guidelines are not mandatory and “are intended to provide general advice about reduction of underwater noise to designers, shipbuilders and ship operators.”  The Convention on the Conservation of Migratory Species of Wild Animals (CMS) developed Family Guidelines on Environmental Impact Assessment for Marine Noise-generating Activities offsite link. These Guidelines provide regulators with advice on how to create Environmental Impact Assessment standards in their respective jurisdiction to manage marine noise-generating activities.

Additional reference information: Some of these links are to external sites.

  • United Nations (UN) General Assembly, A/Res/71/257 offsite link. The UN General Assembly has an annual “Informal Consultative Process” on a different topic each year “in order to facilitate the annual review by the General Assembly, in an effective and constructive manner, of developments in ocean affairs . . . .” The General Assembly decided in A/Res/71/257 that the 2018 “Informal Consultative Process” will have the theme “anthropogenic underwater noise.”
  • 2016 Report of the International Whaling Commission (IWC) Scientific Committee offsite link. The IWC Scientific Committee in its 2010 Report offsite link “strongly recommended” a goal of reducing ocean noise from shipping by 3dB in 10 years and 10dB in 30 years in the 10-300 Hz band. In its 2016 Report, with respect to noise issues in general, the IWC Scientific Committee agreed that there is compelling evidence that chronic anthropogenic noise is affecting the marine acoustic environment, that the lack of scientific certainty should not hinder management actions to reduce ocean noise, and that addressing anthropogenic noise in the ocean is essential to meeting the UN Sustainable Development targets with respect to reducing pollution and fully protecting 10 percent of coastal and marine areas.
  • International Quiet Ocean Experiment offsite link (IQOE). IQOE is the first large-scale, international project of coordinated research on the effect of ocean sound on organisms. It has developed a Science Plan offsite link with the approaches it intends to take to meet its research goals. An IQOE Science Committee was formed to implement the Plan and in January 2017 in London this Committee had its second meeting.