How Sonar Impacts Whales

Most people perceive the world around them predominantly through sight; whales, other cetaceans and many marine species perceive their oceanic world through sound, either passively or by emitting sound pulses then listening for their reflections returning; a technique called echolocation. So for whales, being in the same region as anthropogenic sonar, such as mid-frequency naval sonar and particular the US Navy’s SURTASS LFA (Surveillance Towed Array Sensor System Low Frequency Active) sonar, which when tested off the coast of California was detectable on the other side of the Northern Pacific, might best be compared to our trying to carry on our normal lives with a very bright strobe light repeatedly blinding us. A significant and important difference is that powerful sound waves can inflict damage to all the organs of the body, while a very bright light might blind, temporarily or permanently, but is unlikely to directly kill you.

Whale beachings have become associated frequently with naval training exercises incorporating sonar arrays in submarine detection roles since 2000 when whales from four different species beached in the Bahamas and the area’s entire population of beaked whales disappeared. Whether they died at sea or migrated out of the suddenly inhospitable area is unknown. Although the Navy initially disputed responsibility, an investigation by agencies of the federal government determined that the beachings were due to the use of mid-frequency sonar arrays during a naval exercise. The Natural Resources Defense Council (NRDC) reports that some of the whales that have died in these beachings have been bleeding around the brains and/or from the ears, and some, particularly species of beaked whales, have shown symptoms similar to those caused by a severe case of “the Bends”, the illness caused by acute nitrogen supersaturation and embolisms when a diver rises to the surface too rapidly.

A 2005 report in the peer-reviewed journal “Veterinary Pathology” gave a more detailed report, based on necropsies carried out on 14 beaked whales that beached on the Canary Islands, the strandings beginning about four hours after the start of an international naval exercise in the area in 2002. They found no neoplasms (cancerous tumors) and no inflammation or pathogens indicative of disease. But they did find severe, diffuse congestion and haemorrhaging, particularly around the acoustic jaw fat, ears, brain and kidneys. Congestion in this context refers to over-filling of the blood vessels which in this case has lead to haemorrhaging or the rupturing of those vessels. They also found gas bubble associated lesions (abnormalities) and fat embolisms (blockages) in the blood vessels and parenchyma (soft tissues) of the whales’ vital organs.

Studies were carried out in 2006 using sound and orientation tags on ten beaked whales, seven Cuvier’s beaked whales (Ziphius cavirostris) and three Blainville’s beaked whales also called the dense-beaked whale (Mesoplodon densirostris). Both of these species were among the dead stranded on the Canary Islands. While these whales foraged by echolocation at extreme depths, the deepest recorded being 1885 metres or over a mile down, and took up to an hour to resurface, their natural behaviour during these dives was inconsistent with the likely development of a decompression illness such as the bends. It was concluded that such problems were more likely due to abnormal behavioural responses to naval sonar.

While the European Parliament called on its 25 member states to suspend the deployment of active sonar arrays in 2004 until further studies had been carried out, the US Navy supported by the Bush Administration is still fighting against the limitations placed upon their use of sonar arrays in training exercises that started in a Federal Magistrates court in 2003. The judgement favoured the plaintiffs, several environmental organisations led by the NRDC, determining that the use of naval sonar systems were a violation of the Marine Mammal Protection Act (MMPA), the Endangered Species Act (ESA), the National Environmental Policy Act (NEPA) and the Administrative Procedure Act (APA). Court battles have continued ever since. In January 2007, under a National Defense Exemption, the Navy were permitted to use mid-frequency sonars during training exercises following guidelines from the National Marine Fisheries Service. These guidelines were severely limited following an injunction imposed by a Los Angeles district court in August 2007 and the injunction was upheld by the Ninth Circuit Court of Appeals in February 2008. Nevertheless, the US Navy insists on spending more taxpayers’ money, having obtained the Supreme Court’s agreement to review the matter in June 2008. The US Navy is a military service that is supposed to respect civil authority and control. Apparently only the Supreme Court is acceptable unless lower courts decide their way, that doesn’t seem to show much respect for the US Judiciary.

Secretary of the Navy Winter has stated “We can protect our national security while simultaneously being good stewards of the environment”. It might be interesting to find out what he considers being a good steward of the environment entails, currently some of the world’s navies may well be killing considerably more whales than the Japanese, Norwegian and Icelandic whaling vessels.


Environment News Service (2002) Judge blocks navy sonar tests likely to harm whales. Retrieved from

Fernandez, A., Edwards, J., Rodriguez, F., Espinosa de los Monteros, A., Herraez, P., Castro, P., Jaber, J., Martin, V. & Arbelo, M. (2005) “Gas and fat embolic syndrome” involving a mass stranding of beaked whales (family Ziphiidae) exposed to anthropogenic sonar signals. Veterinary Pathology 42(4): p446.

Natural Resources Defense Council (2008) Protecting whales from dangerous sonar. Retrieved from

United States Navy (2008) Supreme Court accepts Navy sonar request. Retrieved from

Tyack, P., Johnson, M., Soto, N., Sturlese, A. & Madsen, P. (2006) Extreme diving of beaked whales. Journal of Experimental Biology 209(21): p4328.