A Texas-Sized Kill Zone:

Navy's Submarine-Detecting Sonar Has Harmful Side Effects for Marine Life

by James R. Chambers

Because low frequency underwater sound can travel hundreds of miles with little loss of power, it will actually create a "kill zone" several hundred miles in diameter.

The U.S. Navy has developed an extremely powerful Low Frequency Active (LFA) sonar to detect "quiet" submarines, and it has applied for a permit from the National Marine Fisheries Service (NMFS) to deploy it.

However, based on newly available scientific information, this low frequency sonar produces a high intensity sound that, at 150 to 160 decibels, can kill whales, other marine mammals and marine fish by rupturing the delicate membranes surrounding the lungs, swim bladder, or other enclosed air spaces.

The second lethal effect of LFA sonar involves the activation of supersaturated gas in marine animals' blood and in their cells to form small bubbles which can block the flow of blood in the brain (causing stroke) and can rupture the cell walls. This effect will be greatest in deep-diving animals (such as bluefin tuna, swordfish, bigeye tuna and deep-diving whales) that will have the highest levels of supersaturated gasses in their blood and cells.

The source level of this sonar is 240 decibels (equivalent to the intensity of a Saturn rocket). But, because low frequency underwater sound can travel hundreds of miles with little loss of power, it will actually create a "kill zone" several hundred miles in diameter. NATO naval exercises using low frequency sonar conducted off Greece in 1996 killed whales that were more than 100 km away. In the final EIS for its sonar system, the Navy admits that an intensity of 160 decibels (a lethal level) will be felt several hundred miles away from the source. This will create a "Kill Zone" the size of Texas.

The Navy says it wants to deploy this sonar in 80% of the world's oceans (omitting only the Arctic and Antarctic). It has already been, or is to be used, in many areas that are prime habitat of marlin, swordfish, bluefin tuna, mako sharks, bigeye tuna, sailfish, spearfish, wahoo, yellowfin tuna and many other premiere game fish (and their prey species). Such areas include the Bahamas, the continental shelf off New Jersey, North Carolina, the Azores, Canary Islands, California, and Hawaii.

During the spring and early summer, the deep channels between the Bahamas and the larger Caribbean Islands are the center of spawning for swordfish, white marlin and blue marlin of the North Atlantic Ocean. These species' prime summer-fall feeding grounds include the edge of the continental shelf (between the 100 and 1000 fathom lines) from just below Cape Hatteras, North Carolina, to the eastern tip of Georges Bank off Massachusetts; similar areas along the edge of the continental shelf in the northern Gulf of Mexico; and the Azores, Madeira and the Canary Islands (following the extension of the Gulf Stream as the Azores Current and then the Canary Current). The Navy has not evaluated the consequences of its sonar on marine fish.

The Navy cannot proceed unless it is given a permit issued by NMFS, which must consider the sonar's effects under authority of the Marine Mammal Protection Act and the Endangered Species Act. NMFS is in the final stages of making its determination. For more information on the effects of LFA sonar on marine animals, visit the Ocean Mammal Institute's website at .

What can the public do? Express concern in a letter to NMFS' Director, and send copies to your representatives in Congress and members of the Bush administration.


James R. Chambers is a fisheries ecologist, conservationist, journalist and big game fisherman. At the end of his 30-year federal career, he had responsibilities for management of the swordfish and billfish fisheries in the National Marine Fisheries Service. Since 1998, he has directed Chambers and Associates, a scientific consulting firm specializing in the conservation of marine fish and their essential habitats. (Their website.)

A copy of the Biodiversity Legal Foundation's letter to NMFS' Director can be found at this web page.


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This story was published on May 2, 2002.