LFA Sonar: Is it Worth the Risk?
Talk given at ASMS Whale Zone Symposium, Zurich, Switzerland, July 7, 2002
Marsha L. Green PhD
I am here to hopefully get all of you involved in a campaign to stop a dangerous form of noise pollution in the oceans: Low Frequency Active Sonar. LFAS is a military technology designed to detect and track quiet enemy submarines at long range. A ship sends out a very loud low frequency signal which bounces back off of the submarine. Scientists, citizens and organizations have expressed concern about the potential impact of LFAS (including deafness, tissue rupture and stranding) in marine mammals, fish and other marine life because it is transmitted at very high decibel levels and travels over long distances. The effective source level of LFAS is 240 decibels (dB). While some controversy occurs in comparing water and air sound levels, the number the Navy uses to express the conversion between air and water is 61.5 dB. Using the Navy’s conversion factor, the 240 dB source level of LFAS in water would be equivalent to standing 20 feet away from a Saturn V rocket (used to launch the space shuttle) at takeoff. (However, some experts would use different conversion factors which would make the sound energy intensity in water much higher than the Navy claims.) Sound levels in water will also vary greatly depending on salinity, pressure and temperature. According to the US Navy’s own sound charts, LFAS can still approach 160 dB hundreds of miles from the deploying vessel. Evidence from necropsies on stranded whales indicates that severe physiological damage can occur to whales exposed to 150-160 dB of high intensity sonar.
If deployed, LFAS transmissions will introduce increased levels of noise pollution over hundreds of square miles of ocean habitat potentially affecting large numbers of animals. There is a significant body of published research showing that whales start to avoid sounds at received levels of 115-120 dB. This is well documented in a book: Marine Mammals and Noise. My own research on the effects of boat engine noise on humpback whales shows that they will swim away two to three times faster then they normally travel when exposed to 120 dB of engine noise, which is about equivalent to a loud outboard boat engine underwater. Yet the US Navy is asserting that it is safe to expose marine mammals to up to 180 dB of LFAS. One hundred eighty decibels is one million times louder than the 120 dB sounds whales avoid. Also, LFAS transmits in the same low frequency range utilized by several endangered whales (including humpback whales, right whales and blue whales), for communication and other vital functions. The impact of the masking effects of LFAS on their ability to navigate and find food and mates is unknown.
The US Navy plans to deploy LFAS in 80% of the world’s oceans. NATO and other navies also have or are developing the technology and this is why it is important that Europeans understand what is taking place. In fact, NATO countries are planning to cooperatively develop interoperational systems so one country can send out an LFAS signal and other countries can monitor the "echo" which bounces back. What does the US Navy say about LFAS? Quoting from the Navy’s Executive Summary of their Environmental Impact Statement (EIS) on LFAS "Given that a low frequency sound source is loud and can be detected at moderate to low levels over large areas of the ocean, the concern would be that large percentages of species stocks could be exposed to moderate-to-low received sound levels. If animals are affected at these moderate-to-low exposure levels such that they experience a change in feeding, breeding or migrating behavior, then such exposures could potentially have an impact on rate of reproduction or survival" (EIS p ES14).
So that is the question – What is the effect of this technology on reproduction and survival in marine mammals, fish and other marine life? The US Navy tested this technology secretly at least 22 times before the Natural Resources Defense Council found out about it in 1996 and suggested that they write an Environmental Impact Statement (EIS) as required under US law. The Navy agreed to do so. In order to write the EIS the Navy had to research the effects of LFAS. In 1997 and 1998 the US Navy instituted a scientific research program to test the effects of low levels of LFAS on biologically significant behaviors of marine mammals. They studied 4 species of whales for 1 month each. In 1997 they tested it on blue, fin and gray whales off the California coast. They found that blue and fin whales decreased their vocalizations by 50% & 30% respectively when the LFAS sound was on and in-shore migrating gray whales changed their migration routes to avoid the sound. The Navy concluded that none of these behavioral changes were biologically significant (that it would affect reproduction or survival) even though in their EIS they list migration corridors as biologically significant ocean areas.
Whales are acoustic animals. Scientists believe fin and blue whales use vocalizations for finding mates, food and navigating. If fin and blue whales decrease their sounds by 30-50%, this could have significant long term effects. In fact, a recent article in Nature this summer suggests that the low frequency calls made by male finback whales are mating calls. The researchers said noise pollution from shipping and other human sources, such as military sonar, could make it more difficult for male & female finbacks to find each other. This obviously could have long term reproductive consequences.
In 1998 scientists hired by the Navy tested low levels of LFAS on humpback whales in Hawaii. I became concerned and sent a research team to observe whale behavior before and during the testing. Three lone cetacean calves (a humpback whale calf, a dolphin calf and a melon-headed whale calf) were observed in the relatively small LFAS test area. It is highly unusual to see cetacean calves without their mother. Most marine mammal researchers have never observed it. Perhaps the test sounds disrupted the mother/calf ability to communicate and stay together. The scientists who did the tests later published an article in Nature noting that the humpback whales increased the length of their songs by 27% when the low level LFAS sound was on, while other whales stopped singing altogether. Humpback songs are believed to have a reproductive function. Certainly a 27% increase in energy expenditure for a mating behavior could have significant biological consequences. Again the Navy has not acknowledged these behavioral changes as being biologically significant.
In the Environmental Impact Statement (EIS), the Navy concludes that LFAS is safe up to exposure levels of 180 dB. One hundred eighty decibels is one million times louder than 120 dB. And, it is important to understand that all the LFAS tests in 1997 & 1998 were done at exposure levels much lower than the presumed safe level of 180 dB. The Navy’s scientists never exposed animals to levels above 155 dB and usually exposure levels were well below that. The scientists state in their report on the Hawaii tests (The Hawaii Quicklook): "The research did not use the full source level of LFA" and "The playback protocol was specifically designed to expose animals to LFA sounds at levels that are not harmful." In the Executive Summary they say "It will be difficult to extrapolate from these results to predict responses at higher levels."
Unfortunately that is exactly what the Navy did – on the basis of this limited low level testing designed to not harm the animals they extrapolated to conclude that LFAS is safe at much higher exposure levels for all cetaceans and marine life. This is not sound science.
In Appendix D of the EIS the Navy admits "The lack of empirical data in the 155-180 dB range is an issue." Obviously that lack of data is a significant problem because it makes the EIS a nonprecautionary document. Additionally, the EIS does not discuss scientific research that contradicts its conclusions and it makes general conclusions based on inadequate information. The US Marine Mammal Commission and its Scientific Advisors have this to say about the EIS, "…the available information is insufficient to make direct conclusions about the effect of low frequency sounds in the ocean and the effects of those sounds on the hearing and biologically significant behavior of marine mammals." Dr. Hal Whitehead – a noted marine mammal scientist says "The 180 dB criterion for harm to marine mammals used in the EIS is not accepted by the vast majority of scientists. The adoption of the 180 dB criterion has no valid scientific basis."
So, basically we know very little about the impact of low frequency sounds above about 150-155 dB on marine mammals and fish. There is research indicating that several species of fish exposed to underwater sound at levels of 180 dB or higher, for 2 hours or less were adversely affected. Ken Norris and others report that fish are disoriented and fatigued when ensonified by dolphins and conclude that sound pressure levels below 180 dB may cause damage. Quoting from "Physical Effects of Noise on Fishes" Mardi Hastings says that little or no data are available for fish exposed to sound pressure levels between 149 & 180 dB. This is, of course, exactly the same decibel span where we have no data on effects on marine mammals. According to recent data published by the United Nations, two-thirds of the world’s major marine fisheries are currently fully exploited, over exploited or depleted. With entire populations of fish becoming commercially extinct, is it wise to deploy a technology that has unknown effects on already stressed fish populations?
Clearly there is a large gap in our knowledge about the physiological effects of loud sounds on marine life in the range between 155-180 dB. There are no data to support the Navy’s assumption that 180 dB is safe. To develop and deploy high intensity sonars without this knowledge ignores the Precautionary Principle (if an activity might have an adverse effect, don’t do it) and puts the entire marine ecosystem in jeopardy. The President’s National Research Council, in its report "Marine Mammals and Low Frequency Sound: Progress Since 1994" concludes in the Executive Summary, "Our understanding of how marine mammals react to natural & human-made sound is rudimentary." They also express concern about the potential effects of low frequency sound on the marine mammal food chain including zooplankton, fish and turtles. The US Marine Mammal Commission says if the LFAS system is deployed, all species and populations of marine mammals could possibly be affected with effects ranging from death from lung hemorrhage, to disruption of feeding, breeding, nursing, acoustic communication and other vital behavior as well as effects on prey species (US Marine Mammal Commission Report to Congress, 1997). As Dr. Senn pointed out in his talk earlier today, if the food chain is affected the entire marine ecosystem would be affected. We know nothing about the long term effects of LFAS on marine ecosystems nor do we know anything about the cumulative and synergistic effects of several NATO nations deploying this technology along with other high intensity underwater technologies.
So that is what we don’t know about the effects of low frequency sound. Is there anything we do know?
We do know that nine out of nine recorded strandings involving beaked whales mixed with other species have occurred while naval maneuvers were being conducted in the area. Four of these strandings occurred around the Canary Islands in the 1980’s. Another of these strandings occurred in the Mediterranean in 1996 while NATO was testing low-to-mid-frequency sonar. We also know of another well publicized stranding that took place in the Bahamas in March, 2000 while the Navy was using high intensity mid-frequency sonar. For the first time necropsies were able to be performed on some of the stranded animals because they conveniently started to strand on the beachfront property of Ken Balcomb, a marine mammal scientist who studies beaked whales in the area. Here is a short video clip of Ken talking about the stranded whales and the Navy’s responses. This was a 12 minute piece aired on a TV show in the US entitled "Who Killed the Whales?"
While the Navy initially denied that their sonar had anything to do with the Bahamas stranding, a report issued by the Navy and NOAA in December 2001, concluded the "available evidence points to acoustic or impulse trauma" most plausibly caused by the extended use of Navy midrange tactical sonar. Necropsies showed the whales had hemorrhaging in their inner ears & brains.
Some scientists estimate that in both the Mediterranean stranding (with low to mid-frequency sonar) and the Bahamas stranding (with mid-frequency sonar) the whales were exposed to received sound levels of about 150-160 dB. Ken Balcomb, who found the whales in the Bahamas, had this to say about the two strandings:
"I conclude that the whales in the Bahamas incident were adversely and lethally impacted by sonar pings at received levels well below the 180 dB level considered safe for whales. These pings were of much shorter duration (1/10th second) than the proposed LFA (60-100 seconds) pings, I might add."
Ken goes on to say, "This sonar impact at received levels well below 180 dB is likewise well documented in the Greek incident in the report on the NATO stranding (NATO report SACLANTCEN M-133 Annex G).. The first whale to strand did so 40 km from the ship one hour after the acoustic trial commenced. If one takes into account how fast a beaked whale can swim (about 15 km per hour, maximum), it must have been at least 25 km from the ship when the first of its 238 four-second pings was transmitted! At that distance the received level was calculated by the Navy (NATO, Annex G) to be approximately 150 dB. The Bioacoustics Panel overlooked this important bit of evidence of received level for impact."
So the limited evidence we do have indicates that whales can strand and die from received levels of about 150 dB, but the Navy’s EIS claims LFAS is safe up to 180 dB with no empirical evidence to support this statement. It is also important to note that Ken Balcomb has resighted only 2 of the whales he previously had identified around the Bahamas before the March, 2000 stranding. The Bahamas incident may have affected most of the beaked whale population in the area.
At this point in time there seems to be an attempt to ignore earlier research on underwater noise impacts and avoidance levels. In a previous Navy EIS on ATOC (a 195 dB low frequency underwater sound technology) the Navy estimated that physiological harm to marine life could begin at exposure levels above 150-160 dB. Now they are saying that sound exposure levels of 180 dB are safe even though the Mediterranean and Bahamian strandings indicate that sound levels of 150-160 dB can be lethal. And the evidence that noise pollution in the oceans is already a problem for cetaceans is accumulating. Dr. Darlene Ketten, in an Office of Naval Research workshop on human-produced noise in the marine environment in 1998, stated that about 30% of the beached cetaceans she has necropsied show signs of various types of auditory damage. The written workshop report suggests that many animals may be suffering from hearing loss or that hearing loss may be playing a significant role in these strandings. Michel Andre and Darlene Ketten published a paper on the preliminary results from the analysis of the inner ear structure of 2 sperm whales killed after colliding with a ship near the Canary Islands. The whales had long-term auditory damage. How many whales are struck by ships or strand because of hearing damage? If we add LFAS to an ocean already full of noise pollution who knows what the unforeseen consequences could be?
In addition to damage to the auditory system of whales, dolphins & fish, moderate to intense sounds can cause nonauditory types of physiological damage to marine life. There is considerable scientific debate about how loud sounds can cause nonauditory harm to marine animals. Two possible mechanisms discussed by scientists at a workshop sponsored by the National Marine Fisheries Service in April, 2002 include 1) tissue damage and hemorrhage resulting from acoustic resonance in bodily air spaces and/or 2) the acoustically activated growth of nitrogen bubbles in the supersaturated blood and tissues of cetaceans causing the "bends." Three Navy scientists published a paper on acoustically activated bubble growth last November.
Unfortunately in the EIS the Navy limited their discussion about the effects of LFAS on marine mammals to potential damage to hearing and auditory organs. The possibility of nonauditory physiological damage from resonance effects and bubble growth is not mentioned even though NATO and the US Navy had calculated the resonance frequency of airspaces in beaked whales in 1998 and found it to be in the LFAS range. Certainly we should be cautious about deploying technologies that have the potential to kill marine life without having an understanding of how the technology impacts their physiology. The National Research Council in their report "Marine Mammals & Low Frequency Sound" explicitly say "we need research to determine any nonauditory effects of low frequency sound on marine mammals."
Long term changes to populations over years and decades are, of course, the effects of greatest concern. We have no data on long term effects of noise exposure on marine life and such effects are difficult to study especially at sea. Even if we had more scientific data – where would it get us? The Navy’s own research on the effects of low levels of LFAS has so far found that whales vocalize less around low level LFA sounds, they change their migration route to avoid the sound source, and humpback whale mating songs are interrupted and lengthened. All these effects have been dismissed as not biologically significant by the Navy. We also have evidence that Navy high intensity sonar exercises are related to strandings.
What would it take to stop the escalated level of noise pollution in the oceans? Since the Navy ignores short term behavioral changes observed in their own scientific research program and ignores the warnings from 2 mass strandings, and claims that LFAS is safe up to 180 dB with no evidence to support that claim, it seems likely that more research is not necessarily going to resolve the debate.
Intense marine noise pollution (sonar, bombing, seismic testing) will probably not be stopped by more science. It will only be stopped when people like you get together to lobby your government representatives and relevant agencies to pass laws regulating underwater noise, not just LFAS but other high intensity sonars, seismic testing etc., in the same way some countries regulate noise in the air.
As scientists point out in an article in Science (April 2, 1993) "Uncertainty, Resource Exploitation and Conservation: Lessons from History," "controlled and replicated experiments are impossible to perform in large-scale systems." The authors also point out that "our lack of understanding and inability to predict mandate a much more cautious approach…" They recommend acting to curb potentially harmful human activities before scientific consensus is achieved stating that "calls for additional research may be mere delaying tactics." They also point out that scientists and their judgment are subject to political pressure. On this matter it is important to note that the US Office of Naval Research is the leading organization worldwide funding research on the effects of sound on marine mammals. It is problematic when a large portion of the funding for research on noise effects is provided by the same organization wanting to deploy loud technologies.
We simply don’t know enough about the impacts of high intensity sonars on marine life and the food chain to risk deployment at this time. Consequently, regulatory agencies should apply the Precautionary Principle when making decisions about acoustic activities to be conducted by the military and other institutions. This is especially true for decisions concerning LFAS as the Navy has advanced passive listening systems that can safely detect quiet submarines. Passive systems are not harmful to the marine environment and do not reveal the presence of the "listener" as active systems do. Deployment of LFAS may violate the US Marine Mammal Protection Act as well as various international laws and conventions. Perhaps it is time to discuss international agreements regulating noise levels in the oceans.
Addendum: Shortly after this talk was given the US National Marine Fisheries Service (NMFS) granted an exemption under the Marine Mammal Protection Act to the US Navy to operate Low Frequency Active Sonar for a five-year period. The press release issued by NMFS on the decision states that "It has been determined that at 1 km, the LFA sound has diminished to a level that would not cause harm to marine mammals." This is not a valid statement. The truth is that, according to the Navy, at 1 km the sound level of LFAS is 180 dB. As explained in this talk, the Navy acknowledges in their EIS (Appendix D) that they never tested LFAS above 155 dB; there is no empirical evidence about effects between 155-180 dB. And there is evidence that whales can strand at sound exposure levels of about 150 dB of high intensity sonar. By stating that LFAS is safe 1 km away from the ship, the National Marine Fisheries Service is misinforming the public and ignoring the Precautionary Principle which has become a binding norm of customary international law under the UN Law of the Sea.