Advisers to the Nation on Science, Engineering, and Medicine

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Wm. A. Wulf is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council.

www.national-academies.org

The work of this committee was overseen by the Ocean Studies Board of the National Research Council.

The Committee on Potential Impacts of Ambient Noise in the Ocean on Marine Mammals was charged with assessing our state of knowledge of underwater noise and recommending research areas to assist in determining whether noise in the ocean adversely affects marine mammals. The committee was selected to represent a diverse range of expertise, including acousticians and marine biologists, as well as an expert in geophysical exploration. The committee convened four times, beginning in March of 2001, including three open public sessions. A wide variety of experts in the field of marine mammals and noise addressed the committee and submitted materials for review. The committee is indebted to the following for their assistance: Dan Costa, University of California, Santa Cruz; Jim Finneran, Space and Naval Warfare (SPAWAR) Systems Center; Charles Greene, Greeneridge Sciences, Inc.; Richard Heitmeyer, Naval Research Lab; David Kastak, University of California, Santa Cruz; Charles Liberman, Harvard University; Bertl Møhl, Aarhus University; Paul Nachtigall, Hawaii Institute of Marine Biology; Charles O’Neill, Naval Oceanographic Office; Sam Ridgway, SPAWAR Systems Center; Ron Schusterman, University of California, Santa Cruz; Peter Tyack, Woods Hole Oceanographic Institution; and William Watkins, Woods Hole Oceanographic Institution.

In addition, valuable input to the committee’s work was provided by a number of researchers. The committee would like to offer sincere appreciation to Douglas Cato, Australia Department of Defence; Elena McCarthy, University of Rhode Island; Jennifer Miksis, University of Rhode Island; Kevin Smith, Naval Postgraduate School; and Eryn Wezensky, University of Rhode Island.

Two previous National Research Council reports examined the possible consequences of ocean noise on marine mammals. Low-Frequency Sound and Marine Mammals: Current Knowledge and Research Needs (NRC, 1994) provided an initial survey of our understanding of the impacts of marine noise on mammals. The second report, Marine Mammals and Low-Frequency Sound: Progress Since 1994 (NRC, 2000), primarily reviewed the marine mammal research conducted as part of the Acoustic Thermometry of Ocean Climate (ATOC) experiments. Both reports provided a suite of recommendations, many of which still apply and some of which will be reiterated in this report.

Coincident with the deliberations of this committee, two Navy sonar systems received a very high level of attention from the press and environmental organizations. Use of one of the Navy sonar systems, the SQS-53C, a mid-range active sonar, was found to contribute to a stranding incident in the Bahamas. In addition, a separate, low-frequency active sonar system, the SURTASS-LFA, was approved by the National Marine Fisheries Service for use by the U.S. Navy. Both of these systems are discussed in this report, since they contribute noise to the oceans, but neither is discussed in detail.

One of the challenges in preparing this report was to standardize the units of measure. Another was to clarify commonly used terms in underwater acoustics, seismic exploration, and marine mammology. A glossary is included to assist with some of the general terminology in the report.

Chapter 1 of this report provides a brief overview of the issues pertaining to marine mammals and noise and the committee’s approach to answering its charge. Introductory material describes the physics of underwater sound, as a rudimentary understanding of these principles is necessary to understand the material that follows. Chapter 2 describes both natural and human contributions to noise in the ocean and discusses long-term trends in noise levels. Chapter 3 describes effects of ocean noise on marine mammals, focusing primarily on behavioral changes. Models of marine sound and its effects on marine mammals are described in Chapter 4. Chapter 5 contains findings and recommendations of the committee, drawing on the content of the previous chapters.

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report:

Whitlow Au, University of Hawaii, Kaneohe

Douglas Cato, Department of Defence, Canberra, Australia

Robert Hofman (ret.), Marine Mammal Commission, Bethesda, Maryland

Elena McCarthy, University of Rhode Island, Newport

John Potter, National University of Singapore

Henrik Schmidt, Massachusetts Institute of Technology, Cambridge

Jörn Thiede, Alfred Wegner Institute, Bremerhaven, Germany

Peter Tyack, Woods Hole Oceanographic Institution, Massachusetts

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Robert Knox, Scripps

Institution of Oceanography. Appointed by the National Research Council, he was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.