U.S. Navy Leads Research on Effects of Sound on Marine Mammals

PERSIAN GULF (2008 FILE PHOTO) A porpoise plays off the bow of the Military Sealift Command dry cargo/ammunition ship USNS Sacagawea (T-AKE 2). The T-AKE is a new Combat Logistics Force (CLF) Underway Replenishment Naval vessel that can deliver supplies to Navy ships from friendly ports or from specially-equipped merchant ships. (U.S. Navy photo by Lt. Erik Reynolds.)

Focus on Defense:

SAN DIEGO, July 11, 2008 -- The Navy is leading the United States in funding research to determine the effects of sound on marine mammals, according to Rear Adm. Frank M. Drennan, commander, Naval Mine and Anti-Submarine Warfare Command.

Speaking to business and senior military leaders at the San Diego Military Advisory Council's monthly breakfast meeting June 18, Drennan explained the Navy is funding $26 million this year alone.

"It is important to us, and we want to make sure that all this discussion is based on good solid scientific information."

Drennan quoted a National Oceanic and Atmospheric Administration Fisheries report, which noted between 2,500 and 7,000 mammals are stranded on U.S. coasts every year. In comparison, about five stranding events worldwide from 1996 to 2006 have been associated with active sonar, resulting in 37 marine mammal stranding deaths. To add perspective, Drennan noted that several hundred thousand marine mammals are destroyed every year by commercial fishing worldwide. No strandings have been linked to active sonar in Southern California, an area of extensive naval training.

As new data is collected to better understand the effects of active sonar, the Navy adheres to extensive protective measures when it trains with active sonar to minimize potential injury to marine mammals. These measures include pre-searching the exercise area for mammals, extensive use of surveillance and applying specific rules for use of mid-frequency active sonar.

Court rulings require the Navy to shut down active sonar altogether when marine mammals are within 2,200 yards of any sonar source, and the courts have imposed other restrictions. On June 23, the Supreme Court agreed to review those lower court rulings.

"It is my belief that the Navy is a very good steward of the environment…our approach is one of balance," said Drennan, who was explaining how the Navy meets the needs for both defense and environment.

"We recognize our obligation to the environment, but we also recognize our obligation and our duty to man, train and equip ships and Sailors for the most stressing combat that they might have to endure."

Drennan explained that some of the 40 nations that have submarine capability are adversarial and use modern, diesel submarines that are very difficult to detect. "Smart mines" are another problem, which are programmed to move around when detected. Mines have been the primary cause of ship sinkings since the Korean War.

"In most environments, the only way we can detect these quite submarines and these very complex mines is with the use of active sonar. That means we have to make sure we have proficient operators who understand how to use this active sonar, and they have to train in the most realistic fashion they can possibly train," Drennan said.

Maritime exercises such as the multinational Rim of the Pacific, which is held every two years in Hawaii, provide invaluable replication of real warfare because of the varied ocean environment, live weapon use and active sonar use. According to Drennan, Southern California is also a range that provides realism.

"It's a national treasure. I would argue that the reason the Navy concentrates in San Diego is because of the training range, not just for subs, but for a lot of reasons. It replicates many of the environments. The noise level from background shipping, the ocean bottom types, the sound velocity profile and those kinds of things."

The Navy takes seriously the environment within which it operates and any effect active sonar has on mammals. The solution to meet both objectives could be simple.

"Take a balanced approach. It's not a single-factor issue. Balance of stewardship and meeting training obligations," Drennan concluded.

(Story by Mass Communication Specialist 1st Class Larry Foos, Commander, Southwest Region Public Affairs.)

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