Increasing underwater sounds affect dolphins

Imagine living in a world so loud that you can't hear what anyone is saying, and you're so disoriented from the noise that you can't even find your way home. That is the hidden suffering of one of Earth's most cheerful creatures, the dolphin, in an underwater dimension unknown to most of us on the surface.

According to Sounding the Depths II, a report released this week by the National Resources Defense Council (NRDC), new evidence indicates that the rising level of intense underwater sound produced by oil and gas exploration, military sonar and other man-made sources poses significant threats to dolphins, whales, fish and other marine species.

"Ocean noise is an insidious form of pollution," said Michael Jasny, the report's principal author. "The tremendous damage it is doing to life in the sea is becoming more evident with each passing year."

In the darkness of the sea, dolphins, whales and other marine animals use sound to navigate while migrating, to locate each other over great distances for mating, to find food, avoid predators, and care for their young. Manmade noise is interfering with all of these natural activities and is testing the ability of marine animals to survive.

For at least four decades, the Navy has employed mid-frequency, high-intensity active sonar as an element of its anti-submarine warfare program. At present, the military is exempt from the Marine Mammal Protection Act.

According to the NRDC, military active sonar works like a floodlight, emitting sound waves that sweep across tens or even hundreds of miles of ocean. Some mid-frequency sonar systems generate over 235 decibels, as loud as the launch of a space shuttle.

Evidence of the harm such a storm of sound can do surfaced in March 2000, when whales of four different species stranded themselves on beaches in the Bahamas following active sonar use by the U.S. Navy in the area. That's just the tip of the iceberg.

In June of 2003, the Center for Whale Research released a report stating that they delivered a frozen carcass of a harbor porpoise to the NOAA Fisheries National Marine Mammal Laboratory in Seattle. The porpoise was found subsequent to a nearby Navy sonar incident. The National Marine Fisheries Service (NOAA Fisheries) Northwest Marine Mammal Stranding Network in Seattle released their own report in February 2004 following the Navy's mid-range sonar exercises. They reported that between May 2 and June 2 of 2003, they were informed of 14 stranded harbor porpoise in Washington.

The problem surfaced in a big way in July of 2004 when 200 melon-headed whales crowded into the shallow waters of Hanalei Bay in Hawaii during Navy sonar exercises.

Mass strandings and mortalities associated with mid-frequency sonar events are known to have occurred in North Carolina, Alaska, Hawaii, the Canary Islands, Madeira, the Virgin Islands and Greece.
In Sounding the Depths II, the NRDC proposes a comprehensive strategy for reducing noise pollution, including geographic and seasonal restrictions on intense noise from military sonar, technological improvements to reduce sonic damage, better monitoring and population research, stronger enforcement by the National Marine Fisheries Service, and a commitment to international solutions.

At present, there are no domestic or international laws in place to comprehensively deal with ocean noise pollution and protect marine mammals from abuse and injury.