Prompt political action may have resulted in a remarkable conservation success for whales and dolphins. The Canary Islands used to be a hotspot for mass strandings, but there have been no mass beachings since the Spanish government imposed a moratorium on naval exercises in these waters in 2004.

Naval sonar operations have long been implicated in mass strandings, particularly of beaked whales (R. Filadelfo et al. Aquat. Mamm. 35, 435–444; 2009). In 2002, the stranding of 14 beaked whales in the Canary Islands was linked to the use of mid-frequency naval sonar in the area (P. D. Jepson et al. Nature 425, 575–576; 2003). In 2004, four Cuvier's beaked whales (Ziphius cavirostris) were stranded there after an international naval exercise (A. Fernández et al. J. Mar. Sci. Res. Dev. 2, 2; 2012).

These events prompted the Spanish moratorium and led the European Parliament to issue a non-binding resolution in 2004 to stop the deployment of high-intensity sonar until the completion of a global assessment of its cumulative effects on marine life.

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