Noise pollution comes in the form of tankers, cruise ships, private vessels, air guns, Acoustic Harassment Devices, seismic blasting, oil exploration, acoustic thermometry, and the list goes on and on. 

Perhaps one of the greatest sources of noise pollution in our oceans today, and certainly the one capable of doing the most damage, is mid and low frequency active sonar. The sonar used in the past was passive; it basically just sat there listening for unusual sounds. But during the Cold War with Russia, our U.S. military developed active sonar, which had the ability to send out sound beams that would actively look for enemy submarines. After the end of the cold war, this technology was considered unnecessary, but in recent years it has been revived in what the military says is a crucial tool in our national security efforts.

The sonar is deployed from three different sources on board a Navy vessel. Each source creates a sound wave that is 215 decibels. By comparison the loudest animal on earth, the Blue Whale, creates a call that is 155 decibels, equivalent to standing 1 yard away from a jet engine at take off. The three sound waves from the Navy vessel converge to create a sound that is 240 decibels. Because the sonar is low frequency it has the ability to travel large distances, especially under water where sound is carried further than in air. 300 miles away from the source of the sonar, the sound waves are still 140 db, higher than the human pain threshold of 120 decibels. Because this sonar is so loud and travels such long distances it has the ability to injure or kill marine mammals depending on their distance from the sound waves by causing brain hemorrhage, eye and/or inner ear rupture, disorientation, and the loss of their ability to communicate, echolocate, and forage. In a study conducted by the Navy, a 32-year-old man was exposed to sonar at 160 decibels. After 12 minutes he experienced dizziness and drowsiness. He later suffered memory lapse and seizures. Two years later he was still being treated with anti seizure and anti depressant medication.

In 1996 there was a mass stranding of Beaked Whales off the coast of Greece, which was associated with sonar being tested by NATO in the area. In March of 2000 there was a stranding of four different species of whales and dolphins in the Bahamas. Of the 13 animals, 7 died right away. All but one had eye and inner ear hemorrhage. The U.S. Navy accepted responsibility for this tragedy as it was testing mid frequency sonar in the region. Beaked Whales have since disappeared from that particular area. In the summer of 2002 two whales were found dead in the Sea of Cortez, close to where sonar was being used. In September 2002, there was a mass stranding in the Canary Islands, also linked to Navy sonar. In May of 2003, off the coast of San Juan Island, Washington a Navy vessel began deploying mid frequency sonar in the presence of J pod, a resident pod of orcas listed as endangered in Canada and Washington State. The orcas became very agitated and banded close together near shore, remaining at the surface of the water to try to get away from the noise. A Minke Whale, normally a slow moving animal, was seen fleeing the area. Fortunately J pod suffered no visible short-term effects from this sonar exercise, but in the following weeks, 13 porpoises washed up dead around the region. Some of them showed signs of acoustic trauma, however the necropsy results were "inconclusive". This sonar is not only detrimental to marine mammals, it has also been shown to be fatal to fish and fish eggs, attacking the entire marine food chain.

In July of 2002 the National Marine Fisheries Service gave the U.S. Navy a five-year exemption to the Marine Mammal Protection Act in order to use the low frequency active sonar in 75% of the world's oceans. NMFS was subsequently sued by a number of environmental groups including Natural Resources Defense Council, Humane Society of the United States, and Ocean Futures, among others. On October 31, 2002 they were granted an injunction stopping the military from using the low frequency sonar on the grounds that the Marine Mammal Protection Act, the Endangered Species Act, the National Environmental Policy Act and the Administrative Procedure Act were being violated. In August of 2003, the lawsuit was successful and low frequency active sonar was deemed illegal. The Navy then agreed to limit its exercises to a fraction of the area it was using and to non-critical habitat. However, shortly after the ruling, the Bush administration once again exempted the military from provisions of the Marine Mammal Protection Act. They are now attempting to appeal this court decision. Meanwhile, mid frequency active sonar, which is just as loud but doesn't travel quite as far, is still being used by the military. Other countries are also using both mid and low frequency sonar as well, so our oceans are far from safe. Groups like NRDC are continuing to work on getting a worldwide ban of active sonar and they have met with some success. In October of 2004, the European Parliament asked 25 of its members to stop using the sonar until more is know about its potential harm. 

What can you do to help? Pressure the military to stop the use of an obsolete, unnecessary technology that threatens the life in our oceans. Let your elected officials know that if active sonar continues, national security won't be necessary. Once our oceans are dead, we won't be here either. 

Click HERE to visit the NRDC website and find out how you can assist in the fight to stop active sonar globally.

Click HERE to view articles collected by Orca Network about the dangers of sonar to the marine mammal population.

Boat Traffic 

Boat motors cause significant noise underwater, which is quite disturbing to marine mammals. Too much boat noise agitates these animals, and can drive them from their usual breeding and hunting grounds. The biggest problems of this kind occur in high traffic areas, like shipping routes such as Haro Strait, home to the Southern Resident orca pod.

Another disruption to orcas are the multitude of whale watching boats that visit them daily during the summer months. Ironically, these vessels are operated by individuals who love and conserve orcas, and are loaded with sightseers who value the wonder of nature. These are the very people who fight for the rights of marine wildlife and strive to protect them and their environment. If the public has no connection with wild orcas, they will be less likely to conserve what they never see. A balance must be found between loving orcas and loving them to death.

There are ways to minimize the impact of boat noise on our underwater environment:

Slower moving boats are quieter than fast ones. Laws can regulate the speed of boats in wildlife frequented areas.

Proper maintenance of boats helps keep engines running smoothly and quietly. New technology is ever advancing toward better, quieter equipment.

Laws can be established to limit the amount of vessel traffic through areas such as Haro Strait. These laws not only reduce noise pollution, but also help to lessen other environmental problems, like the threat of an oil spill.

Whale watching vessels can strictly adhere to regulations about speed, number of boats in one area, and distance from whales.

People who desire the thrilling experience of encountering orca in the wild can plan a daytrip to one of many spots in the San Juan Islands where the whales can commonly be spotted from shore. One of the best areas for land-based orca viewing is Lime Kiln State Park on San Juan Island.

Click HERE to read the Friday Harbor Whale Museum's guide to responsible whale watching. 

Click HERE for directions and information on Lime Kiln State Park.

Some other forms of unwanted underwater noise are caused by economic or scientific reasons. Seismic blasting used to seek oil, and the drilling once oil is discovered, result in not only noise, but also in chemical pollution and habitat destruction.

Sound waves can also be used to accurately test the temperature of water, by measuring the time it takes for the waves to travel to various points. This information is helpful for determining if our ocean temperatures are increasing due to global warming. But how do these sounds affect the marine mammals in its path?

Another noise problem is Acoustic Harassment Devices (AHD). For example, salmon fisheries in Canada were being plagued by thieving harbor seals. To combat this, the fisheries installed devices that would constantly emit a noise designed to dissuade seals from approaching their fish nets. The result of the AHD's was a mass exodus of marine animals from the areas where the noise resonated. Orcas and porpoises fled in droves, but the clever seals now knew that they could follow the sounds to a free dinner!

State and Federal governments should be made aware of the ill effects that can be caused by certain forms of "progress", and must be encouraged to disallow actions that do our environment more harm than good.

Click HERE to read WSU student, Rebecca J. Bressan's report on acoustic pollution in Puget Sound (pdf. file).