Low-Frequency Sound and Marine Mammals Current Knowledge and Research Needs (1994) / Chapter Skim
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EXECUTIVE SUMMARY
EXECUTIVE SUMMARY
Pages 1-7
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In addition, the committee was asked to consider the trade-offs between the benefits of underwater sound as a research tool and the possibility of its having harmful effects on marine mammals. LIMITATIONS OF CURRENT KNOWLEDGE Data on the effects of low-frequency sounds on marine mammals are scarce.
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Natural ocean sounds are produced by wind, waves, precipitation, cracking ice, seismic events, and marine organisms. The hearing abilities of marine mammals undoubtedly evolved to deal with these natural sounds the ambient noise levels of the ocean.
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In the absence of such an impact assessment, the committee finds itself unable to fulfill the second part of its charge, namely, to balance the costs and the benefits of "underwater sound as a research tool" versus "the possibility of harmful effects to marine mammals." Rigorous experimental research on marine mammals and their major prey is required to resolve the issue of how low-frequency sound affects these species. The committee recommends that future experiments be conducted in such a manner that the received level of the sound and the behavior of the animal can be studied together.
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From page 4... ...
authorization.3 Harassment has been interpreted as any action "that results in an observable change in the behavior of a marine mammal." This interpretation of harassment seems to the committee to be inappropriately broad. Although a scientific research permit may be granted a few months after application, the SIT authorization can take up to two years and may require public hearings.
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Commercial fisheries have had a blanket exemptions under the Marine Mammal Protection Act of 1972 from the prohibition on taking marine mammals, and can kill marine mammals even from depleted populations. Furthermore, the noise from passing marine traffic, including supertankers, is not regulated as harassment or as a "take." Scientific research, especially oceanographic surveys, seldom results in any fatalities among marine mammals, although the sound levels produced in these investigations are intense and could potentially affect large populations.
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However, other recommendations could be implemented under existing laws through changes in regulations. The committee is by no means recommending that scientific research be afforded a blanket waiver of the provisions of the Marine Mammal Protection Act, the Endangered Species Act, and the National Environmental Policy Act that relate to taking of marine mammals, either d-tiring research on marine mammals or on other topics where experiments might incidentally affect marine mammals.
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From page 7... ...
RECOMMENDED RESEARCH The research that would provide some of the missing information is conceptually straightforward biological science, the proposed experiments should provide much of the needed information, and the cost is not enormous compared with that of other scientific efforts of comparable magnitude. The committee's aim was to identify general research needs that are crucial to a full evaluation of the effects of intense low-frequency sounds on a variety of marine mammals and their major prey.
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