Does "235 dB re 1 µPa @ 100-1000 Hz" mean anything to you? As a rough definition of one of the loudest controlled sounds humans have ever made, it is our core concern in a developing operational naval system designated the "Surveillance Towed Array Sonar System, Low Frequency Active". Just call it the LFA. The U.S. Navy has announced an intent to prepare an Environmental Impact Statement under provisions of the National Environmental Policy Act on the still very secret LFA system, and without legal basis, continues to test the system worldwide. CSI's concerns grew on learning that the Navy has concluded that there are no impacts on marine organisms, which they call "biologics", and so no permits or announcements were made or are required, and suitable mitigation protocols have not been defined. Worse still, the Navy has also decided that no one cares. Why? Perhaps because of ATOC. ATOC is a whisper compared to the LFA, but the frenzied ATOC debate, the 2000 faxes and letters to NMFS, and the enormous public, media and political outcry that resulted, has not happened with the LFA. Why the silence? Scoping hearings on the system this summer produced a very small response. A CSI plea to thousands of scientists for expert opinions and facts produced a disturbingly limited response. There may be many reasons for this relative silence, but not the one the Navy embraces. Does anyone care? Yes!
But here CSI wants to make several points absolutely clear. We are not experts, and don't know what effect the LFA will have on the marine environment. That drives our concerns. We are prepared to react to the worst case scenarios and support legal action, yet remain eager to be convinced that the system's operations will have minimal impact. We put the environment first, and very real concerns about critical species like the right whale at the start of a long list. We are not trying to find out all the details of a military system that may be necessarily secret and crucial, and we are disgusted with the vague and arrogant manner the Navy has used to divulge inadequate facts and assert priorities. We are not interested in taking limited knowledge and unlimited concerns to new measures of hyperbole and polemics. We are working to build a consortium of people and organizations able to address legitimate concerns about the LFA in a constructive manner that will produce informed policy decisions; sound policies on sound.
What will the LFA do to marine organisms? Brace yourself; no one knows. Intuitively we all know that human noise has become a major marine pollutant, and that war drives humans to blindly destroy a lot more than each other. A task force commander with an LFA asset may scour other nations' deep or shallow waters anywhere in the world. Thousands of square miles would be impacted with each impulse, repeated often if a threat was serious. One expert speculated that, finding a sub, why not sit over it and perhaps debilitate the crew with the noise? Navy divers have had serious effects from similar noise. A group of California divers have felt their lungs resonate from something similar. Some studies suggest that organisms close enough would die, and sublethal but debilitating effects including deafness would result kilometers away. Fisheries may find their target species affected because of the avoidance reactions. For example, scallops exhausted from fleeing the sounds would lie on the bottom as the net passed over. Many fish species would drop out of net range, or flee the area. Catches would drop dramatically. These are experts speculating; CSI is trying not to. From personal experience it is not speculating to envision one of the remaining 300 or less North Atlantic right whales lying on a shallow bottom to wait out the noise, and suffering a hearing loss as a result. There are very few facts to go on, but facts drive policy decisions and oversight. It is the unknowns that beg legitimate concern over the impact of the LFA on many organisms' behavior, potentially affecting navigation, foraging, communication, breeding and survival. We agree with the many scientists who too quietly said that, without facts, it is the unknowns that demand intuitive guesses, expert opinion, legitimate caution and constructive concern.
So what do we know? Tested secretly since 1988 perhaps 25 times in several oceans, the array creates a dish shaped pattern of very loud, low frequency, variable broadband sound (235 dB re 1 µPa @ 100-1000 Hz) that reaches out perhaps 100 miles, and finds the threatening submarine by faint echoes. There will be four dedicated vessels divided between the Atlantic and Pacific Fleets, each to deploy a towed array about 100 meters deep at three knots, pulsing on a 10% duty cycle. The Navy has given a figure of 160 dB at about 2 km from the LFA, and there is a classified range at which no human diver is allowed in the water. Experts' guesses have the 150 dB level as far out as 10-25 km, and 120 dB level at perhaps 200 km. And then they hastily add that the variables are enormous, the calculations will vary significantly with conditions, and no one should quote them. Understandably. And more cause for concern.
235 dB re 1 µPa @ 100-1000 Hz is meaningless to experts without distance references, and to the rest of us without metaphorical comparisons. As it weakens with distance and conditions it is still noise excessive enough to cause temporary and permanent hearing loss. The limited facts don't tell us what behavioral or physical reaction or impact to expect at a given range of a given source under given conditions. This is complicated, confusing stuff, and don't forget that the LFA is a moving source. One expert's calculated guess equated what we would hear as a very loud airplane as an equally loud noise a whale would hear 3.2 km from the LFA, and that within 1 km the >170 dB noise might cause pain. Over 50% of gray and bowhead whales have been observed to avoid drillships at a distance where the perceived broadband sound was about 120 dB re 1 µPa. Sperm whales become silent with many man made sounds, and no one knows the social impact we cause. Yet some observers report cetaceans actually approaching loud sound sources, as if curious. And nature provides earthquakes, volcanic activity, iceberg calving, and many other acoustic overloads. When does it matter to the organism? When should it matter to us?
Can the LFA deafen whales? In one case, during a series of industrial explosions in Canada, observers could detect no significant reactions from the group of whales foraging in the area, but two humpbacks that died entangled in nets three days later had had their ears destroyed. It took a great deal of expert effort to determine that, and leaves us to wonder at other mortality events, and the critical need to fund timely and appropriate research. What of the humpbacks that didn't blunder into the nets? Immediate death is just one aspect. One humpback took almost a year to die of dehydration and starvation after a crippling net entanglement that prevented foraging. Not hearing well enough to find food, a deaf whale is a dead whale. There are many levels of hearing loss, and other related traumas, and the LFA is not an explosion. Complicated stuff, and before you ask, dolphins don't hear as well in the LFA frequencies, but then there are wavelength related and cavity resonant effects that may have an impact beyond hearing ranges. Dolphins indeed may be less affected, but studies show some avoid seismic surveys.
Many creatures may escape an LFA zone, and perhaps avoidance behavior will reach out a very long way. Will that in turn disrupt migrations, or feeding and breeding areas? What of those that can't escape, or choose not to? Right whales seem resigned to tolerate all the coastal human impacts we can dump at them, occasionally oblivious even to boats nearing impact. If there are fewer than 300 North Atlantic right whales and the loss of only one to human impact is considered a critical problem, what will happen to right whales caught too close to a LFA operation that decides to wait it out? A very slow whale that hears all too perfectly in the LFA output range may be close enough to feel pain, or perhaps suffer a hearing loss that may cause a very slow death. We may never know unless they float ashore dead and we can afford to fund the research that will tell us.
It is not speculation to consider the many species of whales that communicate in the LFA band. Besides masking or confusing whatever they are doing, would the LFA sound biological, even sentient to them? This leads to a potential project to answer many more critical questions: An LFA research operation directed by a team of cetacean specialists and other marine biologists, with adequate survey support to assess the reactions of local cetaceans to controlled LFA outputs, may be the most significant need of the EIS and may answer enough questions. Mandatory civilian oversight of the LFA system is a greater requirement, and would necessarily include bioacousticians, cetologists, and marine biologists. From this comes the dilemma of credibility, where scientists will be funded and supported by the Navy, yet be tasked to ultimately quantify the LFA impact and provide facts policy makers can use for sound policies. But is there any other way? We need to know.
To help with that, as stated above, CSI is working to build a consortium of people and organizations able to address legitimate concerns about the LFA in a constructive manner that will produce informed policy decisions; sound policies on sound. Between now and the expected Draft EIS next August the issue will get louder. CSI will fight to keep this issue from dissolving into the frenzy that ATOC became. If you have an interest in helping, or knowing more, please feel free to contact CSI. Perhaps we can all make the LFA the alert we need to develop truly sound policies.
Refer to the next article on the LFA: Navy Noises Continue, in Vol. VI No. 1, January 1997
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