Marine Mammals: Underwater Noise


Marine Mammals Home Right Whales Ship Strikes Underwater Noise

Hawaiian monk seal.
Photo 22: 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. 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.

 (last updated October 13, 2017)