Cetacean Society International

Whales Alive!

Vol. VI No. 3 July 1997


Update on the Low Frequency Active (LFA) Sonar

by William Rossiter


We promised to keep you informed about the U.S. Navy's latest and most powerful sonar, the LFA, and its potential effect on cetaceans and other marine life (see Whales Alive!, October 1996). One of many loud human noises in the oceans, the LFA may now help us understand the impact of some of the rest. Shipping is the overwhelmingly dominant source of manmade noise, and has increased ambient noise levels by 10 dB from 1950 to 1975. A wide variety of other non-natural sound sources that could also impact marine life include explosions, seismic exploration, sonar, and acoustic telemetry. We are impacting the ocean's creatures and habitat with an ever increasing din. But no one can say how much and how badly; there are simply too many unknowns. Because of the unknowns few management or constraint policies can be developed, much less enforced. The only certainty is that ships are getting faster and louder, and that species like the right whale may be closer to extinction for it. What to do?

The Low-Frequency Sound (LFS) Scientific Research Program is an attempt to do something. It began with the gratifying willingness of the U.S. Navy to make their classified SURTASS LFA test ship available to scientists, with funding to support a complex and optimistic research project ($2.5 million in FY 97). The Navy's unique sound source and analytical equipment would be used to study the reactions of whales to loud sounds. Operational LFA sounds, some like humpback and blue whales' calls, would help the Navy understand the potential impact of the LFA. Others may fill in more general gaps in our knowledge about human impacts. The Navy has given scientists the chance to use the best equipment there is, as vast an improvement over any other acoustic research program as a CD is to a 78 rpm record. The project will expose specific cetaceans, many of whom will be tagged, to very specific sounds. The received level, a computer model of what the whales will hear under the actual environmental conditions, will be modified or increased until there are reactions. The reactions may tell us what characteristics of sounds cause impacts.

Of course there's a catch. The classic dilemma, in fact. Is it worth the risk? Given all that no one knows, and the few bits that are known, this project intends to come very close to being a major impact on target animals. There may be many more impacted but unmonitored. What will it kill? Will it cause harm? Will it disrupt critical behavior? Can the observers actually know these things? This all depends on the intentions, controls, and mitigation procedures of the project's participants. And in our faith in them.

Will the results provide suitable data that will enable decision-makers to develop management tools for constraining manmade sounds? Will the final data be of value to society, and not just to science? Will it help cetaceans and other marine life that we all know are being impacted by our sounds?

Christopher Clark of Cornell, Peter Tyack of Woods Hole, and William Ellison of Marine Acoustics are the leaders of this project. There will be many other scientists involved, with satellite and radio tagging, monitoring from many platforms, and data work. Can the leaders bring such an enormous array of people and technology together in a very optimistic schedule, and make it all work in spite of weather and unexpected problems? Can they accept scrutiny and doubt without being insulted? Can they convince the many doubters that they have the same concerns for the cetaceans' well-being, or will they seem intent on science at almost any cost? Will the results be quickly shared for public oversight and management decisions, or will they be squeezed through the ponderously slow machine of scientific literature and protocol?

The Navy has been increasingly open about the system. CSI has been to many meetings and we are convinced that they are strongly committed to preventing the LFA from doing harm to marine mammals and turtles in tests and training operations. The Navy recognized the need to study the impacts so as to prevent them, and appear to be giving unprecedented access and funding to achieve that goal.

How will this project be mitigated so that harm does not occur? Mitigation for SURTASS LFA test operations is based on visual or acoustic detection of marine mammals or turtles within 3 nm 1 hour prior to a test, a short term ramp-up to allow move away time, and shutdown of source if marine mammals are seen within 1 nm of the source. LFS mitigation assumes less of a source level, includes ramp-up, or shutdown if an animal is detected 100 m from source or certain other responses are observed. There is also an Acoustic Integration Model to estimate exposure levels, to minimize the chances that any group is exposed to >160 dB re 1 µPa, and to ensure that the focal group is exposed to playback protocol levels. What's the magic about 160 dB? It is the operational limit, but is an almost arbitrary level decided by NMFS. Will harm occur below this level? How can we know? Is the monitoring adequate? What of the unmonitored marine life? Migration is a critical time for gray whales. Would they have room to escape inshore of any "blocking" sound? Will any of this cut off the migration? With humpbacks some of the questions revolve around the simple truth that the project seeks to disrupt the breeding behavior of an endangered species. Can the total true impact be known? Is it still worth the risk?

CSI hasn't taken a position on the LFA/LFS project yet. We have been as involved as any environmental organization could be, and we are going to continue to assess the project objectively, and report on it without hype. If this project was motivated merely by scientific questions we would oppose it flatly. If we can help make its motivation ensure adequate data to enable the management of manmade sounds in the ocean we may support it. The Draft Scientific Research Permit raised many questions, and we have hopes that they will be answered satisfactorily. The schedule is extremely optimistic. The implications are that the project would be continuously modified as required, and lesser goals may result. In the end it means that we must be convinced that the people and technology will work to quantify and minimize the impacts on marine life affected by this research, and that the results will be rapidly and openly available to all. It may indeed be worth the risk. Something must be done about manmade noise in the oceans.


Refer to the next article on the LFA: Item in News Notes, in Vol. VI No. 4, October 1997

Previous articles on the LFA:


Go to next article: Explosions at Fernando de Noronha Island or: Table of Contents.

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