Recent reviews of mitigation measures to minimize impacts of high intensity sound sources, for both seismic surveys conducted during oil and gas development and military activities, have been critical of the standard methods (which tend to rely on visual observers) as being inadequate, concluding that they cannot prevent cetaceans from being affected by sound. An effective method to protect the cetaceans from the behavioral changes triggered by exposure to sonar sounds would reduce the appearance of the unusual “bubble” lesions described in beaked whales.

In September 2002, fourteen beaked whales from three different species stranded in the Canary Islands during an anti-submarine warfare exercise in the area. In July 2004, at least four beaked whales died after an international naval exercise. Four other mass strandings, all associated with naval activity, struck the islands in the years before. This situation motivated a non-binding resolution of the European Parliament in 2004 (B6-0089/2004), calling its Member States to adopt a moratorium on the deployment of high-intensity active naval sonars until a global assessment of their cumulative environmental impact on marine mammals, fish and other marine life was completed. The same resolution also recommended the Member States to immediately restrict the use of high-intensity active naval sonars in waters falling under their jurisdiction.

The unusual ‘‘bubble’’ lesions discovered in several of the beaked whales that stranded during military exercises near the Canary Islands were similar to those found in cases of decompression sickness. It was subsequently postulated that these whales might have unusually high levels of dissolved nitrogen in their blood and that rapid ascent as a result of behavioral changes triggered by exposure to sonar sounds might cause ‘‘bends’’-like lesions. The bubble lesions might therefore arise if animals are forced to or near the surface for an extended period, or into very shallow water. In short, the studies suggest that the lesions may result ‘‘from an abnormal behavioral response to sonar’’, possibly as the result of beaked whales exhibiting an ‘‘anti-predator’’ avoidance response when exposed to sonar noise.

Following this recommendation, the Spanish government passed a moratorium on naval sonar in the Canary Islands in November 2004, banning its use within 50 nautical miles of its jurisdictional waters. During the 14 years that have passed since the moratorium was put in place, there have been no atypical mass strandings in the Canary Islands, probing its effectiveness as a mitigation measure.

In order to protect one of the most important areas for the cetaceans in the North Atlantic, all the countries and regions of the Macaronesia must be encouraged to adopt the mid-frequency active (MFA) sonar moratorium on their EEZs in order to extend the positive effects that the moratorium had on the cetacean populations of the Canary Islands.

Madeira and Azores and the Canary Islands, as EU territories are directly concerned by the B6-0089/2004 resolution of the European Parliament and their willingness to set up a MFA sonar moratorium in their EZZs would mean the protection of over 40% of the Macaronesian Region.

Expanding the MFA sonar moratorium to all the rest of the countries in the region would mean an effective protection of over 3,5 Million square km, which represents 85% of this biodiversity hotspot for cetaceans.

• Asociación Guyra Paraguay Conservación de Aves [Paraguay]
• Asociación Herpetológica Española [Spain]
• Centro de Extensión Universitaria e Divulgación Ambiental de Galicia [Spain]
• European Association of Zoos and Aquaria [The Netherlands]
• Fundación Biodiversidad [Spain]
• Fundación de Conservación Jocotoco [Ecuador]
• Fédération des conservatoires d'espaces naturels [France]
• Loro Parque Fundación [Spain]
• PROVITA [Venezuela]
• Sociedad Española para la Defensa del Patrimonio Geológico y Minero [Spain]
• Vice Consejería Sostenibilidad Ambiental, Gobierno Vasco [Spain]