NRDC report - 'Sounding the Depths. Supertankers, Sonar and the rise of undersea noise'

Following is the Executive Summary of a recently released report produced by the Natural Resources Defense Council, entitled 'Sounding the Depths - Supertankers, Sonar, and the rise of undersea noise'. It is a comprehensive report that discusses increasing underwater noise, highlighting some of the threats that are faced by marine animals, including cetaceans. It discusses the proliferation of noise, the problems and hotspots and NRDC's findings and recommendations.

The full report can be found at the link address below.


It is a commonplace among divers and oceanographers and all those who spend time in the sea that the ocean is no "silent world," as Jacques Cousteau had written, but an exceptionally noisy place. Some of the causes are natural and precede us: the winds that rile the ocean surface, the tremors that shake the floor, and the calls of great whales, which carry for hundreds of miles. Over the past century, however, as we have come to exploit the sea with unprecedented industry and scope, the noise has grown. Now entering the mix are supertankers and container ships, airguns and drilling rigs, pingers, ringers, loudspeakers of various types and functions, explosives, dredges, and active sonar systems -- their consequences for marine life uncertain, but potentially significant and grave.

Our purpose in this report is to draw attention to the emerging risks. While we applaud the interest that regulators have recently shown, we find the governments current policy on ocean noise to be uneven in application, piecemeal in approach, and wholly inadequate to the broad ecological challenge that this kind of pollution poses. To help meet the challenge, we recommend measures that are at once more comprehensive, more pragmatic, and more cautious.

The Rise of Ocean Noise

There is general agreement in the scientific community that hearing is probably the primary sense of whales, dolphins, and other marine species, as vitally important to them as seeing is to us. Most marine mammals depend on sound as they hunt for food, detect predators, find mates, and keep their herds together in the darkness of the sea. For the great whales and others, much of this activity takes place in the low frequencies, in the band below 1000 Hertz. Unfortunately, that part of the spectrum is also occupied by some of the loudest human sources of sound.

The impact that one of these sources can have on an animal depends partly on its distance. At close range a powerful sound can cause tissue in the lungs, ears, or other parts of the body to rupture and hemorrhage. Farther away, the same sound can induce temporary or permanent hearing loss. And at even greater distances, it can affect behavior, leading animals to swim off course, or abandon habitat, or stop vocalizing, or turn aggressive. In addition, any loud noise has the potential to drown out other sounds -- calves, mates, predators -- around the same frequency, a phenomenon known as "masking."

By some estimates, ambient noise in the worlds oceans rose by as much as 10 decibels, one full order of magnitude, between 1950 and 1975 alone. Much of the blame belongs to shipping: with the advent of the global economy the size of the merchant fleet has doubled, gross tonnage has quadrupled, and the cumulative noise from so much traffic has come to dominate the lower frequencies in many regions of the world. Then there is the offshore oil industry, focused domestically in Alaska and the Gulf of Mexico, whose exploration and development of the continental shelf are responsible for a variety of acoustic disturbances. In the last decade, three new sources of noise pollution have come onto the scene. Here and abroad, the U.S. Navy and NATO have been developing low-frequency, active sonar systems with a potentially global range of operations. In California and Hawaii, the Scripps Institution of Oceanography has been readying loudspeakers for an experiment in acoustic thermometry, measuring changes in ocean temperature by the time sound takes to travel long distances underwater. And throughout North America, commercial fisheries have been deploying acoustic deterrence and harassment devices, with only minimal guidance from wildlife agencies. These applications differ widely in scope, duration, and intensity, and as a matter of law and policy their ecological impacts must be explored.

In 1994, a special committee of the National Research Council reported that data collected on ocean noise and marine mammals were "extremely limited" and could not form the basis of "informed prediction or evaluation." Additional research has since been undertaken, partly under the auspices of the Navys Low-Frequency Active Sonar (LFA) and Scripps Acoustic Thermometry (ATOC) programs as well as the marine mammal program at the Office of Naval Research. But the scope of this research was narrow, focusing on acute effects from just a few types of sound. We have learned, for example, that gray whales exposed to 120-decibel sounds tend to deviate from their migration paths and that sperm whales faced with higher levels can fall silent for hours or days; yet the significance of these reactions is uncertain, and their cumulative impact, like those of the rise in ambient noise, is unknown.

For many marine species, we assume there exists an acoustic threshold of viability -- a level at which basic, biologically essential activities are so frustrated as to risk the welfare of entire populations. For some species, as far as we know, it is possible that line has already been crossed.

Ecology and Equity

As yet there is no law to deal comprehensively with ocean noise. The closest approximation is the Marine Mammal Protection Act (MMPA), passed by Congress in 1972, when the consequences of whale hunting and tuna fishing were beginning to concern the public. In principle it is a deeply precautionary document. It places a moratorium on private or public actions that intentionally "harass, hunt, capture, or kill" marine mammals (the so-called "take" provision); requires those who "take" animals incidentally, as an unavoidable consequence of their business, to first obtain permission from one of the wildlife agencies, either the National Marine Fisheries Service or the U.S. Fish and Wildlife Service; and strictly bars all activities, incidental or not, that have more than a "negligible impact" on protected species and stock. For all its good words, however, the MMPA is not ideally suited to a problem of such magnitude as ocean noise. Geared to an ad hoc permit system, it cannot deal broadly with the source levels
that polluters generate or with the total amount of noise produced in a given area. Aimed at marine mammals, it fails to cover sea turtles, fish, and other species, or marine communities in general, and even those it covers are impracticably split between two agencies. On top of this, it grants exemptions to certain activities -- commercial fishing being the most prominent -- that make a fair application of the law impossible.

The lack of guidance from Congress, the sketchiness of the science to be applied, the formidable size and complexity of the industries to be affected -- these have induced a type of inertia within the wildlife agencies and have led them to be less aggressive in their enforcement than the law requires. In issuing permits under the MMPA, the agencies are obligated to ensure that polluters effect "the least practicable impact" on marine mammals and their habitat, "paying particular attention to rookeries, mating grounds, and areas of similar significance"; yet the "means" and "methods" that they prescribe for noise control too often fail to go beyond visual monitoring. And because the agencies havent published a clear and cautious definition of "harassment," most polluters dont bother to seek a permit and remain entirely outside the law.

No matter the cause -- by any standard of ecology or equity, the current system is paradoxical. The worst offender, international shipping, is also the least regulated, and while over the last decade the National Marine Fisheries Service and U.S. Fish and Wildlife Service have received a number of permit applications from oceanographers, not one has come from the massive supertankers and cargo ships that degrade our coastal habitat. The wildlife agencies, having withdrawn themselves from the greater part of the problem, are now looking to reengage. Congress has yet to take up the issue.


Defining the Problem

Dr. Sylvia Earle, former Chief Scientist, National Oceanic & Atmospheric Admin.

Undersea noise pollution is like the death of a thousand cuts. Each sound in itself may not be a matter of critical concern, but taken all together, the noise from shipping, seismic surveys, and military activity is creating a totally different environment than existed even 50 years ago. That high level of noise is bound to have a hard, sweeping impact on life in the sea.

Regulating these sound sources can be difficult, but one has to start somewhere. Every breath we take is dependent on the ocean. And unless we really understand how that vast system works and take better care of it, it isnt just the ocean thats in jeopardy. Its our whole future thats at stake.


Findings and Recommendations

The Natural Resources Defense Council first began to focus on ocean noise in 1994, as the U.S. Navy was preparing a five-year series of "ship-shock" trials -- involving tons of high explosives and hundreds of detonations -- for an area just outside the Channel Islands National Marine Sanctuary. After losing the court battle, the Navy reconsidered the risks, and ultimately the program was abandoned. But before long, news of the ATOC and LFA projects began to surface, and we realized that our recent confrontation over "ship-shock" was symptomatic of a much wider problem. Since then, NRDC has fought to put undersea noise on the nations environmental agenda. When the Scripps Institution sought to place one of its ATOC loudspeakers inside the National Marine Sanctuary at Monterey Bay; when the U.S. Navy began to deploy its global active sonar system without filing an Environmental Impact Statement; when Exxon, U.S.A., proposed to run high-energy seismic surveys in species-rich waters off the Channel Islands, we spearheaded opposition and, through advocacy and negotiation, brought each one to modify or defer its plans. At the same time, we have joined the search for a long-term solution, serving on task forces and panels with representatives from all sides.

Although after five years of advocacy we remain troubled by the magnitude of a problem too long overlooked, we are encouraged by an increasing recognition within the government that something must be done. The recent effort by officials in the National Marine Fisheries Service and elsewhere to establish an Interagency Coordinating Group and hold workshops on the issue is an especially hopeful sign. Nonetheless, the distance that lies between the present regime and a truly effective, proactive policy of species and habitat protection is considerable.

To help bridge that gap, we offer the following recommendations:

Formally acknowledge the problem. Until the scale of the problem is recognized and the measures proposed for its reduction are as serious and comprehensive as those taken for other forms of pollution, the problem cannot be solved. It is unlikely that Congress will take these steps before the agencies report the weaknesses inherent in the current system, develop the factual evidence of the problems scope, and commit themselves within the available law to a broader approach.

Update the Marine Mammal Protection Act. Congress should pass legislation that gives the wildlife agencies power to regulate "source levels," the noise that polluters actually generate; rescinds the exemption allowed fisheries for their acoustic harassment devices; revisits the "general authorization" granted certain scientific activities, which is overly broad; extends any noise control standards that arise under the Act to vulnerable populations of sea turtles; and charges the Coast Guard or another competent agency with the task of enforcement.

Set cautious standards. The wildlife agencies can improve the permit system by setting clear, cautious standards, especially at the initial threshold where permits are required; addressing scientific uncertainties by using the most conservative data available; and developing a matrix of behavioral responses that discriminates between significant and trivial effects.

Regulate with habitat in mind. There is much that the wildlife agencies can do under current law to protect marine habitat. They should identify acoustic "hotspots" -- biodiverse, densely populated, or critical habitat that is subject to high annual or seasonal levels of noise; designate critical habitat for endangered and threatened species, as the Endangered Species Act requires; and through the permit system (and other vehicles) prescribe means of reducing disturbance in these areas.

Create marine reserves. Just as terrestrial habitat is secured within a system of national parks, monuments, and preserves, so should our marine habitat. The National Oceanic and Atmospheric Administration should tighten restrictions on activities within our National Marine Sanctuaries; Congress should expand the list of sanctuaries or create a new system with tougher standards of conservation management.

Require appropriate mitigation. The wildlife agencies should fulfill their obligations under the Marine Mammal Protection Act and in issuing permits prescribe "methods" and "means" of effecting "the least practicable impact" on protected species and their habitat.

Ensure the safety of divers. The agencies must adopt standards to protect the welfare of scuba divers, particularly from activities sited near the coast, and must require operators to notify the public through newspapers, diving journals, and other media well in advance of their actions.

Establish an advisory panel to guide research. To provide funding for research of a general nature and to avoid conflicts of interest, members of the Interagency Coordinating Group on Acoustics should create a pool of funding and establish a neutral, expert advisory panel to administer it. Among the research priorities: determining the acoustic sensitivities of baleen whales and other species; studying the cumulative, chronic, and population-level impacts of noise on marine life; and investigating effects on fish, invertebrates, and sea-plants, which have been relatively neglected. The National Science Foundation should provide funding for those avenues of research that fall within its guidelines.

Seek an international solution. The cooperation of the international community in curbing undersea noise pollution should be obtained, first by bringing the issue before such bodies as the World Conservation Union and Biodiversity Conference (which could launch a global study) and the International Maritime Organization (whose approval is essential in matters of shipping), and ultimately by including noise pollution standards in international agreements. A regional agreement among North American states should also be sought.