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Year: 2003
Editors: Mark Simmonds, Sarah Dolman and Lindy Weilgart
Publisher: Whale and Dolphin Conservation Society
Pages: 165 pp (PDF is 1.2mb)
Price: free
To order:URL: http://www.wdcs.org/

Anthropogenic noise is an insidious form of pollution in the world's oceans. It is also an issue of continuously growing concern for scientists, non-governmental organizations, and the general public, heightened most recently by the highly publicized mass strandings of beaked whales in the Bahamas. While the report's title suggests that it will address noise issues for all marine species, it actually primarily focuses on cetaceans (whales, dolphins, and porpoises). This should not dissuade the individual who is concerned with undersea noise issues, especially since sea turtles are likely affected by human-made noise. This report certainly will serve as a useful reference.

Oceans of Noise begins with a brief primer on the physics of underwater sound. Granted, the topic of marine acoustics is complicated, and unfortunately, this primer will not be the easiest to follow or understand by the average reader. The reader who is interested in the mechanics of sound propagation would be better served by referring to other materials for this type of tutorial. This report highlights the many sources of noise pollution in the marine environment today, including (but not limited to) commercial ship traffic, oil and gas exploration and production, ocean experiments involving acoustics, military sources, acoustic harassment devices, dredging, and marine wind farms. This report section commences by sketchily mentioning biologically important sounds, but then neglects to develop the presentation by not discussing the importance of these sounds (except in the case of wind and wave-generated noise and listing some basic characteristics of natural noise sources). It is obvious at this point, that the report's focus is directed towards human-made noise sources. This is a spot in the report where the concept of passively listening by dolphins for sounds produced by fish could have been introduced; this would also have served as part of a good foundation for the next chapter's discussion on why we should be concerned about the masking of biological sounds by human-made noise. There has been very interesting progress along these lines, which suggests that passive listening is employed by bottlenose dolphins occurring in estuaries, to locate their prey. These shallow waters also happen to be the nosiest in terms of anthropogenic sounds (e.g., boat traffic).

A few omissions were noted for the before-mentioned chapter, though it is important to understand that a comprehensive review of anthropogenic noise sources in the ocean is a massive undertaking. For example, it would have been interesting to see an inclusion of information on sounds produced during fishery operations. In the case of trawling vessels, animals may respond to cues, such as sounds produced by boat operations (e.g., winches operating) and nets as they move through the water. The report attempts to be broad in geographic terms, however, it is obviously biased primarily to information from the eastern North Atlantic Ocean (where the Whale and Dolphin Conservation Society [WDCS] incidentally is based). For example, seismic surveys occur to a high degree in the northern Gulf of Mexico and studies are underway to assess the impacts to cetaceans in that part of the world, however, no referral to this area or studies is provided. For this to be a thorough review of anthropogenic noise sources, the section on vessel traffic should have touched upon whale-watching and research survey efforts by scientists involving ships, as well as small boats. These topics are somewhat addressed in the appendices, as a list of responses of cetaceans to boat traffic and guidelines for whale-watching (in the Mediterranean), but could have been more directly addressed in the front of the report. This would have been a nod to the concerns of scientists, particularly in the U.S., who have long complained about the restrictions imposed on them for studying dolphins, but the lack of such compliance by or enforcement of the shipping industry, which is probably the biggest of the ocean's noise makers. It is here that we see that the primary targets of the WDCS are noise sources such as the oil and gas industry and the military, and to a lesser degree, the fishing and shipping industries. Equally noteworthy is that there is no discussion of the effects of noise from aircraft as a contributor to ocean noise (this is only listed under oil and gas production-related noise sources in a table), and responses by cetaceans to these sound sources.

The report progresses to discuss noise as a problem for cetaceans. It was disappointing to see the cursory discussions in this section, since this would seem to be the section in the report that warrants the most information, and it essentially forms the foundation for the need of management of anthropogenic noise sources. Understandably, this would have been a huge undertaking. A number of key articles and reports were missed in this section, particularly relating to the issue of stress, which is a major concern in terms of multiple sound sources over the course of time, since sublethal impacts of noise have the potential to cumulatively result in lethal impacts to animals.

A review of relevant international marine pollution laws is provided in addition to recommendations for an urgent action plan to provide essential information regarding these acoustic sources and how to possibly mitigate impacts. Defining what types of sounds could potentially harass marine mammals and endangered species, and cause "takes"¹, is the single most pressing need in acoustics (and assessing impacts to marine species), particularly in term of defining "harassment" (e.g., disruption of behavioral patterns) to animals. The report appendix provides what is reputed to be a comprehensive list of recorded examples of disturbance of cetaceans by vessels (hint: a comprehensive listing of such responses by sea turtles to both vessels and aircraft would be an invaluable contribution to sea turtle biologists and regulatory agencies alike). As noted earlier, the marine mammal biologist well-versed in reactions to boats by cetaceans will immediately realize that this is a summary of such information for some geographic locations, but is by no means a complete listing.

In conclusion, this is an admirable attempt to review a volatile topic. This report will hopefully prompt readers to understand that, as noted by Mark Simmonds, the WDCS Director of Science, "Despite the many unknowns that remain, it is apparent that noise pollution in the seas should be regarded as a fundamental threat to marine wildlife in general". "It is important that this is recognized at both national and international levels and that every effort be made to address it."

¹ The term "take" is statutorily defined to mean "to harass, hunt, capture, or kill, or attempt to harass, hunt, capture or kill".

Dagmar Fertl, Geo-Marine, Inc., 550 East 15th Street, Plano, TX 75074, USA. (E-mail: dfertl@geo-marine.com).