Talk presented at the Fifth Annual Whales Alive Conference, Maui, HI.
ATOC and LFA sonar: undersea noise pollution and the limitations of science
Jan. 18, 1997
Levels of human-generated undersea noise have increased significantly since the beginning of the industrial age. Much of this noise comes from shipping and boating, undersea dredging, drilling, construction, seismic surveys, sonars, and ocean science studies. There are some who feel this is not a problem, but it seems unrealistic to me that cetaceans, who are so vitally dependent on sound, will somehow be unscathed by this latest assault on their environment. While whales and dolphins have presumably evolved over thousands of years to deal with naturally- occurring background noise, the elevated noise levels that we are causing are new. Cetaceans have not yet had a chance to evolve mechanisms to cope with this. Whales and dolphins, as you probably know, depend on sound for communication, food-finding, navigation, and predator detection. Toothed whales emit echolocative clicks to find their prey, whereas the baleen whales probably only locate their prey by listening, as well as using other cues. In the case of the sperm whale, the species I am most familiar with, up to 1/3 of its body is devoted to sound production and reception. These whales are rarely silent and are particularly sensitive to noise. In fact, we wouldn't be able to study this animal in the way that we do, if they were quiet for any length of time, because we track them by the clicks they emit. Sperm whales use a highly-developed means of communication which sounds like our Morse code and has been the subject of my research for the past 11 years or so, on and off.
Recently, I have become concerned about two new, very loud sources of noise that have been added to the already noise-polluted marine environment. One is the ATOC project which is an oceanographic project to measure ocean temperature and supposedly increase our understanding of global warming, and the other is the Low Frequency Active sonar program which has recently been developed by the U.S. Navy to detect quiet enemy submarines. ATOC stands for Acoustic Thermometry of Ocean Climate and is an at least $43 million project (to date) funded by the Dept. of Defense, using your tax dollars. The project is run by Scripps Institute of Oceanography. The idea is that, since the speed of sound is faster in warm water than in cold, average temperatures for whole ocean basins can be determined merely (and I use the term "merely" advisedly) by repeatedly broadcasting very loud sounds into one side of an ocean basin and measuring the time it takes for the sounds to arrive at the other side. In the case of the Pacific Ocean, we're talking about some 6,500 miles from California to N.Z. Even though these sounds will travel through an extremely efficient conductor of sound called the deep sound channel, this is still a very long distance requiring a very loud sound. As you probably know, one of the first two loud underwater speakers is to be placed off the north shore of Kauai, and the other site used to be directly IN the Monterey Bay National Marine Sanctuary, but opposition forced its relocation to Pioneer Seamount, which is close to two National Marine Sanctuaries--the Monterey one and the Farallon Islands one. Not a great improvement. Dr. Munk, chief scientist for the ATOC project, has an unerring instinct for choosing those sites for his underwater speakers which are home to a large quantity and diversity of marine life, and which local people feel most deeply about preserving. The ATOC signal is on for a duration of 20 mins. every 4 hrs. around the clock, mostly every fourth day, but there are some periods when it operates every day. The sound source is low in frequency or pitch (75 Hz--toward the lower end of human hearing) and located at a depth of about 1 km. While ATOC has obtained federal permits to operate for 2 yrs. or so, the long-range ATOC proposal calls for 10-12 additional underwater speakers in all oceans of the world to be broadcasting over a decade at least. The Navy's Low Frequency Active Sonar Program is a part of the Surveillance Towed Array Sensor System or "SURTASS" which used to just use passive listening to detect enemy submarines. With the development of new, quieter submarines, however, the Navy began the LFA Sonar program which actively sends out very loud, low-pitched sound pulses and listens for echoes from submarines or other targets. LFA sonar has been under development since 1980, and has been extensively tested especially from May 1992-October 1993, mostly in deep water between Hawaii and Oregon. These so-called "Magellan sea trials" have also occurred in the Mediterranean in 1993, off California in 1994, off Oman in 1995, and on at least 25 other occasions around the world. "Follow-on systems" will apparently be installed and used on a specific class of new Navy vessels, however the Navy maintains it is only building 4 such 72-ton LFA sonar systems. In the late 1980's and early 1990's, regional conflicts increasingly took place in shallow coastal regions rather than the expected deep water threat. As a consequence, the Navy has developed and tested LFA sonar in shallow waters, as well as in deep waters. Shallow waters present additional problems for the detection of enemy submarines because of interfering noise from ships and boats, underwater terrain, different temperature profiles, etc. Unfortunately, this proposed use of LFA sonar in shallow water is particularly worrisome for cetaceans. Coastal waters are the most productive areas, used by an abundance and diversity of marine life, including cetaceans. As this Coastal Zone Color Scanner photograph shows, the vast majority of the ocean regions are deserts, except for the coasts. Migrations also generally happen close to shore. LFA could potentially be establishing a sonic barrier to the migrations of endangered whales. And many naval facilities are located near very sensitive cetacean habitat, e.g. off California (where there is a great diversity of cetacean life), Florida (the right whale calving grounds), and Hawaii (humpback breeding grounds). In deep water, the source is likely to be far from harmless, however. Even when the LFA sonar is transmitting in deep water, it will only be deployed at a maximum depth of 250 m, which is well within the diving abilities of most marine mammals. According to the Navy, however, the sound will be directed downwards, which would be an improvement. Testing and transmission of the LFA sonar is ongoing, although apparently only in the Pacific. It is regrettable that the Navy does not feel, due to security reasons, that it can inform marine mammal scientists ahead of time where these tests will take place. Thus there is a greater potential that high-risk cetacean habitat will be chosen as a test site. In addition to the incredible loudness of this sound source, the frequency or pitch of LFA sonar also puts cetaceans at great risk. The frequency at up to 1 kHz is much higher than ATOC's, and well within the hearing range of the vast majority of marine mammals.
The Navy refuses to divulge the specific characteristics of this sound source for security reasons and will only say it is between 100 Hz to 1 kHz. The sonar pulse is generally less than 1 min. in duration which means that cetaceans are more sensitive to it than if it were an instantaneous impulse of much shorter duration, like that of a seismic pulse. Sonar pulses will be broadcast at a 10% duty cycle such as a 1 min. pulse every 10 min. or a 3 sec pulse every 30 secs. The LFA sonar will be mainly used for the protection of a moving battlegroup, and thus while the ship is transitting, according to the Navy. The Navy plans to deploy the LFA sonar in coastal waters of the U.S. and deep and shallow water sites world-wide. When faced with such potential harm to the marine environment from these loud sound sources, I think we, as citizens, have to take a good, hard look at the supposed benefits to be derived from these programs, as well as any less-invasive alternatives. Do we really need this? It may be difficult, as members of the public, to adequately evaluate the threat which would necessitate LFA sonar, but we need to be convinced that LFA at least really works, can't be interfered with or defeated by enemies in conflict, and that there aren't any alternative methods of detecting quiet submarines, especially passive methods.
Similarly, with ATOC. The purpose of this project is supposedly to help us understand more about global warming. Whether this project will actually work in terms of detecting systematic temperature trends in the ocean over and above the variation in temperature that is present naturally, is highly debatable. The ocean changes naturally from one decade to the next, from completely unknown causes. Even supposing this project does work, how can one relate, say, a rise in ocean temperature with global warming and not some completely natural process like the reverse of an ice age? And how much MORE will we actually understand about global warming just from ATOC, how many years or more probably decades will it take to gain this supposed knowledge, and could all this be accomplished by much less invasive and expensive means--say for instance, by using thermometers? These are all questions that have never been adequately and forthrightly addressed by the ATOC team.
And then, of course, there's the marine mammal issue, which is how I became involved with ATOC. In the fall of 1993, I was a post-doctoral fellow at Cornell University's Bioacoustics Research Program with Dr. Chris Clark. He was (and still is) head of the Marine Mammal Research Program which is funded directly by ATOC, and is, in fact, a part of ATOC. This over $5 million program is charged with determining whether marine mammals are affected by the ATOC noise. Dr. Clark is a very competent, well-qualified scientist so I thought no more about ATOC, until I came across some research and various anecdotes which I found unsettling. I heard that unprecedented nos. of humpback whales were becoming fatally entangled in fishing nets in an area where blasting was taking place. I heard that sperm whales were lifting their heads (and ears) high out of the water whenever seismic ships using loud airguns passed by. I heard of some seal species in polar waters who strangely were unable to detect motor boats approaching them closely from behind. I read a recent study of gray whales (esp. mothers and calves) which cleared out of a breeding and calving lagoon for a month after being played certain types of underwater noise. And I read about two major studies on migrating grey whales and bowhead whales which showed that these whales clearly changed the course of their migration to avoid average noise levels of about 120 dB. The fact that there was this consistency in the noise level avoided is remarkable. Fish also seem to show avoidance to similar noise levels. For comparison purposes, the ATOC signal strength of 195 dB at 1 m is 10 million times louder than the 120 dB level which these whales and fish so consistently avoid. LFA sonar, which may be up to 250 dB, is 10 trillion times louder than the level we know whales to avoid. Remember that the decibel scale is a logarithmic one, so that a 10 dB increase represents a sound 10 TIMES as loud; a 20 dB increase 100 times as loud.
And then there was the Heard Island Feasibility Test. This was the precursor to ATOC, only louder. Dr. Munk again unerringly chose an area in the Southern Indian Ocean which was home to a large number of marine mammals. Moreover, despite warnings from marine mammalogists, Dr. Munk chose to proceed with the test during the peak of the marine mammal feeding season for the Antarctic. A biological study was slapped together at the last moment, so that Dr. Munk could get his permit. This study couldn't conclude much, but it did find that there was unequivocal evidence of behavioral effects on marine mammals from the sound transmissions. Especially sperm and pilot whales completely fell silent during the noise, and sometimes didn't resume their normal vocalizing for a day or more. For sperm whales at least, this meant that whales were not feeding during this time. Dr. Munk concluded from his experiment that such a loud sound wasn't necessary for his purposes, which makes one wonder why he didn't bother to find the minimum intensity level required from the outset, rather than start loud and work down. These studies and anecdotes all indicated to me that undersea noise can mask cues that highly acoustic marine mammals are using to, for instance, avoid becoming entangled in nets, and that marine mammals such as the polar seals may already be hearing impaired from the noise of loud icebreakers, and that whales may be sensitive to noise and try to avoid it in a way that could critically affect their calving and feeding success, and thus the whole health of their population.
These are the most serious effects of noise on populations--those which affect growth and reproduction. And yet, the ATOC marine mammal research program is unable to study such effects for ANY whale or dolphin species! This is a major deficiency in ATOC's marine mammal research program, considering that modest increases in noise have already been shown to reduce growth and reproduction in a variety of marine organisms. Two fish species suffered significantly lower growth rates with only a 20 dB increase in background noise level. Egg viability was also reduced. Shrimp showed reduced growth and reproduction, and increased mortality and aggression. An increase in ambient noise of 20 dB would result in roughly a level of 90-110 dB. To compare this to ATOC, this level would be heard above background noise at about a distance of 3,500 km from the ATOC speaker, or over about one-quarter of the whole vast Pacific Ocean. Adversely affecting the reproduction of marine organisms over 1/4 of the Pacific is not trivial, even if it is only in the deep sound channel. And remember, LFA could be 100,000 times louder than even ATOC and it would not be restricted to the sound channel. While acousticians have guessed that the strength of the signal is from 235-250 dB, the Navy has only committed to saying that the loudness of the sound will be no higher than 160 dB beyond about 6 km distance from the source. Bear in mind that the only good study on hearing impairment from underwater noise was done on goldfish, and this points to 150 dB being the level at which physiological damage to hearing begins. Very rough calculations show that the 150 dB level could extend out as far as 10-25 km. Imagine placing the hearing of marine life at risk over a radius of 25 km! And if one looks at how far the range would be for sound levels of 120 dB which whales so consistently avoided, we come up with figures of about a 500 km radius around the source. To put this in perspective, a 500 km radius translates to about 800,000 sq. km over which the behavior of whales and fish could be changed. This is an area greater than the state of Texas. So, although there is great uncertainty regarding the impacts of noise on marine life, pretty much everything we DO know points to concern. Even humans are not immune from the effects of loud undersea noise. Some Navy divers exposed underwater to 160 dB for only 15 mins. may have suffered from long-term effects such as depression and seizures as a result of the loud sound. Certainly our lungs and other air cavities in our bodies will resonate or vibrate at particular low frequencies, possibly to the point of rupture. The main disturbing misconception that the ATOC issue has brought to fore, is that science will somehow be able to solve our problems and dictate our policies. In fact, science has been shown over and over again to fail in this regard. Many, if not most, environmental problems have not been foreseen and only belatedly recognized, e.g. DDT, ozone depletion, the collapse of fish stocks, and even global warming. Science has very real limitations, and irrefutable evidence is hard to come by, especially when dealing with complex ecosystem effects. Even if such clear evidence is obtained, it is usually obtained much too late for corrective action. This leads me to question both the worth of the ATOC project in constructively dealing with global warming, and the value of the MMRP in safeguarding marine mammals.
For instance, in the case of ATOC's MMRP, there is no way to document the effects of noise on stress levels, growth rates, feeding rates, reproduction, and mortality ON ANY WHALE AND DOLPHIN SPECIES. Whales and dolphins are notoriously difficult to study in the wild, since one is lucky to even sight a fin or a blow or exhalation of a whale. For these animals, baseline calving rates, growth rates, mortality rates, and even population estimates are virtually unknown or are extremely inaccurate. Yet it is precisely these variables which are not only the most likely to be the ones affected by the ATOC or LFA noise, but which are the most essential indicators of the health of a population. We are categorically unable to determine whether ATOC or LFA noise interferes with a sperm whale's ability to find food at depth, a blue whale's ability to find a mate, or causes increased stress resulting in lower fertility. We are not even able to detect hearing loss, certainly not in any of the great whales. Hearing loss could, in fact, be easily misinterpreted to mean that whales are habituating or getting used to the noise. It is also impossible to infer long-term effects by studying only effects over the short-term. Very minor and subtle responses in the short term can translate into severe negative impacts on the well-being of populations over the long-term. For instance, a recent study of caribou showed that even a brief startle response to noise from fighter jet overflights resulted in significantly higher calf mortality. The authors theorized that this was because the startle response caused mothers and calves to move, however briefly, out of safer, more optimal areas, and thus become more exposed to predators like wolves. These effects are hard to predict. No one also predicted that the distant noise from undersea blasting operations could cause more humpback whales to blunder fatally into fishing nets, yet this is what happened.
This is why the much-touted preliminary finding by the Marine Mammal Research Program of ATOC, stating that whales do not seem to be leaving the area or showing overt behavioral changes, doesn't really mean much. So what? They could be staying because ATOC picked a productive, rich part of the ocean in which to place its speaker, and the whales are simply unwilling to move out of an area if their food is there. Similarly, you don't have to see short-term responses to get long-term harmful effects. Stress levels resulting in miscarriages or decreased growth rates could be rising and there is no way the MMRP is equipped to detect these. Also, keep in mind that ATOC's MMRP considers times when the ATOC signal isn't broadcasting, "controls", yet we know that LFA sonar was tested off California during this time period. Indeed, LFA-like sounds were recorded in the same general area by members of the public. So it is difficult to tease out what impact other very loud noise sources had on the MMRP results, which could really cloud the issue. In the case of LFA sonar, the Navy isn't even required to get a permit from the regulatory bodies of our government. The Navy simply states that LFA sonar is unlikely to adversely affect or harass any endangered species, and the National Marine Fisheries Service, whose responsibility it is to protect cetaceans, blithely agrees and signs on the dotted line. This, despite the fact that preliminary results of LFA sonar trials note "very subtle, short-term (<2 min.), occasional changes in vocalization patterns of finback whales as a result of LFA transmissions." How occasional were these changes? Only less than 50% of the time. I don't consider it occasional when a finback whale changes its calls about half of the time it hears LFA. We don't even know for sure why finbacks call, though we suspect it is to find mates. How can we possibly make any responsible decisions?
So we are faced with a problem. We have endangered marine mammal species who are highly sensitive to and dependent on sound for their survival. For sperm whales, which have a maximal rate of increase of just 0.8%, their populations are just barely increasing or are staying constant. We can't keep expecting that these animals will keep finding ways to adapt to yet another assault on their environment. "Windows" of silence are becoming a scarce resource. Cetaceans are slowly being envelopped in an "acoustic fog" in which the important aspects of their world are becoming less and less distinct. So, these animals are already stressed and there is probably not a whole lot of "play" in the system anymore. We have good evidence that marine mammals can be displaced from critical habitats by noise, can suffer hearing loss, and can otherwise show disturbance from undersea noise. So what do we do? I think we need to clearly and humbly acknowledge that, while research on the effects of noise pollution is worthwhile, it can not provide us with the answers that we need to safeguard marine life from the potential effects of ATOC or LFA noise. ATOC's MMRP is limited to detecting only the most obvious short-term effects. Instead, I think we should ask ourselves (and by we, I mean we the public, not we the ATOC scientists or the Navy), whether this project is really and truly necessary in terms of concrete benefits to our world. Will ATOC really be able to prove whether global warming exists and will it do so in time? Or is it just another delay tactic used to avoid actually tackling the problem of global warming? And are there really no adequate (maybe not ideal, but adequate) alternatives to acoustic oceanography? Similarly, is LFA really necessary? Is the threat from enemy submarines so great and can't this be overcome some other way? Only if we are convinced that a project fulfills these requirements should we proceed. Secondly, I believe we should concentrate on risk-reduction rather than putting all our hopes on research providing evidence of safety, which it can't. The single most valuable course of action in this regard would be to place the sound source out of harm's way, away from areas rich in life. We generally choose a desert instead of a rainforest in which to conduct nuclear tests. As I mentioned, both of the ATOC sites for its sound sources are in productive areas used by an abundance and diversity of marine life. Similarly with LFA: it will be deployed in coastal areas and likely affect areas that are critical to marine life. Unfortunately, it looks as though ATOC will be allowed to proceed over a couple of years, but I think it is imperative that it not operate over decades or several ocean basins. The speaker off Monterey has been transmitting for over a year already. At least the sound source off Kauai doesn't look like it has been installed properly yet, because the cable snapped as it was being positioned. Recent press releases note that the source will be re-installed this summer. The scale over which LFA operates is even more terrifying, as these ships will be going world-wide, even to presumably such sensitive areas like the Arctic. When we talk about decades and all oceans of the world, it just becomes too risky. Some things one just doesn't do. So I am making a distinction here between using science to assure us of the safety of a project, which I feel is dishonest because it's not possible; and using science to gain information to help us decide how best to reduce risks and mitigate harm, which I think IS reasonable. And what of the larger issue of undersea noise pollution? I agree it should be studied, but again, I feel that enough is known about the effects of noise on marine mammals to know that less noise is better. This should warrant a serious effort toward reducing our output of noise. I don't believe this needs to be as painful as it sounds, since making ship engines quieter also makes them more efficient. One can accomplish a great deal in reducing noise, simply by maintaining engines well.
Quieter engines can also be built--it is well within our technological capability. We've made jet engines radically quieter, and we can do the same for ships. But I do NOT think the solution lies in the addition of yet more, new, systematic sources of noise, like ATOC, under the guise of studying the effects of noise pollution. This is a perversion of science. We have plenty of already existing sources of noise which are available for study, without adding to the problem. And I think some noise sources like LFA sonar are simply too loud to allow under any means. Let us concentrate instead on minimizing noise in our oceans, not only for the sake of the marine inhabitants, but most likely, also for ourselves.
Lindy Weilgart, Ph.D., Research AssociateDept. of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4J1 Canada Ph. (902) 494-3723; Fax (902) 494-3736 e-mail: HWHITEHE@IS.DAL.CA
Please write your local political representative to express your concern about these issues (ATOC, LFA sonar, and undersea noise pollution in general). Please make a copy and send to :
Joel Reynolds, Natural Resources Defense Council (NRDC), 6310 San Vincente Blvd., Suite 250, Los Angeles, CA 90048, Ph. (213) 934-6900
|Last Updated April, 1998 by Sascha Hooker|