Effects of Naval SONAR on Marine Mammals and Recommendations for Reducing Deleterious Impacts

Defense Date


Document Type


Degree Name

M.S. Marine Biology

First Advisor

Caryn Self-Sullivan

Second Advisor

Tamara Frank


Technology advancements have allowed Navies worldwide to advance and try to stay one step ahead of non-allied nations, and having a weapon with greater range than the strongest weapon of a non-allied navy, or being able to detect a non-allied weapon at a larger range than their weapon will reach is of highest importance (Commander Pacific fleet; Lautenschlager 1983; Buck and Clavert 2008). Active SONAR has provided this solution and has remained the most valuable tool in our nation’s defense, particularly in anti-submarine warfare (Yusof and Kabir 2012; Commander Pacific Fleet; Buck and Clavert 2008; Kiamos 2002). Without the use of active SONAR the security of our nation, our fleets, and even national and international economies could be in jeopardy (Kiamos 2002; U.S. Fleet Forces Command; Krajewski 2008). But all of this good does not come free, active SONAR can have deleterious impacts on marine mammals (Ellison et al. 2011; Wiggins 2002; VanDyke 2004; VanDyke et al. 2004). Mass strandings are occurring more frequently and usually in spatial and temporal correlation to Naval SONAR exercises (Wiggins 2002; Parsons et al. 2008; Natural Resources Defense Council 2014).

This paper delves into the current literature concerning the effects of Naval SONAR on marine mammals to present each stakeholder position in a non-biased manner. Literature was collected via search engines such as Google Scholar, Web of Knowledge, Web of Science, and EBSCOHost. Current regulations and environmental impact statements were found on the website for the Department of the Navy. Personal interviews were conducted along with questionnaires, in order to gain perspective into beliefs and thought processes of each stakeholder group. Sources were analyzed to find any correlations between the author affiliations, funding source, and publication to the conclusion and overall tone of the paper.

The U.S. Navy stands strong behinds their mission and believes in doing everything possible to fulfill their charge of “maintaining, training, and equipping combat ready forces capable of winning wars, deterring aggression, and maintaining the freedom of the seas,” which includes extending warning times and distance from adversaries (Kiamos 2002; U.S. Fleet Forces Command; Krajewski 2008). Technological advancements in weaponry and warfare have made active SONAR essential for national security (Commander Pacific Fleet).

Research scientists focus their work on discovering the physiological effects and possible behavioral effects of SONAR on marine mammals. Studies have largely been conducted on the hearing thresholds, masking levels, and temporary and permanent threshold shifts for various species (Wright et al. 2007; Mooney et al. 2009 a, b; Southall et al. 2000). Responses, both behavioral and physiological, varied based on age, sex, current activity, health, and previous exposure, making it difficult to predict the true effects SONAR would have on marine mammals as a whole (Myrberg Jr. and Arthur 1990; NAP 2003; NRC 1994; Southall et al. 2000). Observed effects include respiratory changes, cardiac changes (NAP 2003), changes in dive behavior and resting behavior (Myrberg Jr. and Arthur 1990; NRC 1994; Mooney et al. 2009 a, b; Miller 2009), and decompression sickness (Jepson et al. 2003; Jepson et al. 2005; Cox et al. 2006; Fahlman et al. 2014).

Environmental, political, and recreational stakeholders have long opposed the Navy’s used of active SONAR. These particular groups largely consist of members from the general public and publications produced consist of blogs and newspaper articles, with few scientific papers. They feel that SONAR is a valuable tool for national defense, but still feel that stricter regulations need to be in place to protect marine mammals. Lawsuits have been filed throughout the years in order to make this happen (Wiggins 2002; Parsons et al. 2008; Natural Resources Defense Council 2014). They raise concern over the current “safe decibel limit” of 180 dB re 1 μPa( “re 1 μPa” is used as the unit of measurement for sound underwater) and whether it is set too high or needs to be adjusted for different species (VanDyke et al. 2004; Parsons et al. 2008).

Publication analysis revealed no correlation between the publication source (i.e. types of magazines or journals, etc.) and the conclusion or tone of the paper. There appeared to be a correlation between the author affiliations and the conclusion or tone of the paper. An even stronger correlation was found between the funding source and the conclusion or tone of the paper, as papers with Naval funding showed little to no effect of SONAR on marine mammals, conservationist funded work presented harsh effects, and funding sources from more neutral investors produced papers that typically fell in suite with the author affiliations. When analyzed together instead of individually, these factors played with or against each other and either strengthened or neutralized the tone of the paper. A comparison of references showed that there were common sources found amongst the stakeholders. Some were used in a select way that best supported the author’s intentions while others were used in the same manner by each group. The questionnaires revealed that stakeholders have very strong beliefs on this subject, but not all of them fall into the stereotyped thought process for their stakeholder group. More research is being done to examine this harmful relationship and how the varying factors interplay. But with published work largely showing bias, as seen by the literature analysis, people are being influenced to feel stronger support for one group or the other. Environmental, political, and recreational advocates have been opposing the Navy and taking them to court for years, and the navy has rebutted. While this debate rages on, harm is still being caused to both marine mammals and national security. This paper is an attempt to explain both standpoints in a fair manner while also providing unbiased research to show the information that each party needs to consider. Being able to see each stakeholder’s standpoint and understand why they feel the way they do is the first step to reaching a suitable compromise.

After reviewing the literature and the main problems discussed about SONAR and marine mammals, recommendations were made on technologies that could be used to reduce SONAR’s deleterious impacts. While some of these tools are already in use, increased use and/or a “toolbox” approach with them could be used to reduce the amount of active SONAR being used. These resources include: passive SONAR, magnetic anomaly detection, unmanned vehicles, GIS, electromagnetic waves, advanced signal processing, increased environmental awareness, sniffers, and more, fully-trained, marine mammal scouts.

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