Cetacean Society International

Whales Alive!

Vol. VII No. 4 October 1998


Noise in the Oceans: How Much Is Too Much?

by William Rossiter, CSI President


For several years Whales Alive! has been commenting on the debate about how much human noise in the oceans is too much, particularly to cetaceans. Happily, the debate seems to be growing. CSI has often joined the debate between scientific, political, governmental, commercial, environmental and military interests. We've tried to report with objective detail, in hopes that Whales Alive! readers shared CSI's view that the probability of human acoustical impacts is real, excessive, and growing. We are intent on fairly representing public concerns that whales and dolphins are being impacted by our collective din, and that something must be done to lessen it.

Our focus began with ATOC, as reported by Whales Alive! editor Brent Hall. ATOC is now gone "in its present form" (they just won't give up), leaving behind a wake of public mistrust and a valuable study in poor communications between the scientific and public communities. How much harm did ATOC do? No one really knows.

The U.S. Navy's Low Frequency Active Sonar has been a CSI focus for several years. The Draft Environmental Impact Statement for the LFA is due perhaps by Christmas. The DEIS is certain to provoke much debate, eventually in the courts. Will the LFA impact the environment, specifically marine life? No one really knows.

In September the U.S. National Marine Fisheries Service held a workshop to address acoustical criteria for anthropogenic noise in the oceans. NMFS will soon rewrite the official rules on what human sound levels in U.S. waters are allowable. A most impressive panel of scientific experts discussed current knowledge before an audience of diverse industry, military, and environmental representatives, including CSI President William Rossiter. Other acoustic workshops have been and will be held, mixed results may be expected, but the recent interest in the subject is welcome news to all who care about marine life. How much impact could these experts say our noise is causing? No one really knows.

The overall impression from the workshop and elsewhere was that there is little empirical evidence that major human noise producers have had a deleterious impact on marine life. This was one heavily promoted "result" from ATOC. To some this means the issue is closed and we should all move on to other issues. No news is good news. So why is CSI still alarmed? The only proof that we have seen is that scientists haven't yet learned how to get the data. No data does not mean no impact. What we haven't seen enough of, at every level, is the "precautionary principle"; that in the face of ignorance and uncertainty we should proceed with caution. Isn't this the most appropriate approach to the issue? At the moment the very best scientists don't have the facts to help the government write the rules on schedule. So the rules will again be conservative estimates, perhaps vulnerable to legal challenges.

We rely on science to give us empirical evidence about the real world, in part to understand what humans are doing to it. The key word here is "empirical", hard facts. It was evident at the workshop that current science is unable to quantify behaviors that indicate that a sound is having a negative impact on a cetacean individual or population. The true effects may be subtle and long term, and are expensive and demanding to define through research. The panel discussed qualitative behavioral cues of significant acoustical effects, such as interfering with predator or danger detection, separation of mothers and babies, abandonment of core habitat, "vigorous" errors in navigation and obstacle avoidance (e.g. strandings), major panic reactions, stimulated agonism (e.g. attacking objects), sleep disturbance, haul out disturbance of pregnant pinnipeds, and long term problems such as stress. Lesser effects not considered generally significant on smaller scales included migration, mate selection, feeding, and changes in dive or respiration patterns. The panel was unable to conclude enough about the potential significance of human noise masking cetacean communications to include it in either category. Notice how accepting this abstract definition would remove the LFA Scientific Research Program, and possibly the LFA itself, from official contention as an acoustical source of significant impact. CSI contends that invaluable opportunities to measure some impacts have been ignored; the scientists either never thought of them or dismissed their value. A recent meeting to discuss the connection between a mass stranding of beaked whales and a NATO sonar system had only secondary clues to work with; the whales' ears were not sampled for physiological trauma. The "Quicklook III" report shows that the LFA Scientific Research Program in Hawaii last March ignored large scale behavioral cues, albeit anecdotal, that suggest that humpbacks and others a long way from the LFA source moved still farther away. Why shouldn't the burden of proof be to demonstrate that the redistribution didn't occur, or that it wasn't significant to this endangered species on its breeding grounds. Understanding the implications of such impacts of human noise on a wide area or population is invaluable. The implications remain unknown only because science didn't ask the right questions. That we will never know does not mean there was no impact.

Uncomfortable with so much ignorance about behavioral cues for acoustical impacts in the wild, the tendency among the panel was to rely on very limited data from small experiments on captive mammals to define physiological effects beginning with Temporary Threshold Shift (TTS). For example, captive dolphins were exposed to very loud sounds, and then their temporary hearing loss was measured. Extrapolating these meager results to find TTS estimates for other marine mammals, much less free dolphins, is at best questionable. But to some it is the only hard data available, and they are not comfortable with anything less. This fosters the attitude that official concerns should start at TTS estimates, rather than behavioral impacts. To achieve this data, by the way, these dolphins were treated inhumanely; had anyone observed wild dolphins chewing on docks, charging objects, and trying every possible way to get their heads out of the water in response to nearby noise many alarm bells would have rung. That these were U.S. Navy dolphins "at work" at a closed facility brings up many more questions.

There is no doubt that the effects of human noise is a complex issue. Much of the argument for more caution is based on personal experiences, anecdotes of cetaceans apparently reacting to noise. Even this distinguished NMFS panel resorted to using personal hearing experiences to make various points. Anthropomorphic comments are normally the bane of scientific discussions. Here they helped people communicate and were most useful, demonstrating both an open minded effort to help and a recognition that we can't really say much about the perceptions in other life forms. The popular attitude that a "deaf whale is a dead whale" was questioned by a study of the ears of a few stranded or entangled cetaceans. Some had lived for years with profound deafness! How many cetaceans have a hearing problem? How many live well in spite of that? How many boats hit whales that just can't hear them coming?

CSI's alarm comes from the implication that no data means no impact. Without empirical data many scientists are reluctant to make expert guesses or demand caution. Some are not reluctant, increasingly calling for the "precautionary principle". In the absence of hard facts the noise makers argue that they can make more. That will be the main argument of the LFA DEIS. Some scientists, perhaps as part of their nature or their paycheck, argue that caution demands proof. Is CSI's alarm at this backward approach justified?

We all know that the ocean is full of sounds. Thunderstorms, earthquakes, calving icebergs, cetaceans and a host of other source create very dramatic levels that could deafen us, but we aren't designed to live there. Cetaceans have evolved to deal with these noises, and their own. Perhaps they aren't deafened because their inner ears have special muscles to protect delicate structures. They may have many adaptations, and in fact they may be able to cope with our noise too. That would be welcome news. Prove it.


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