Beaked whale strandings list & report

List of Beaked whale strandings related to military sonar or seismic surveys

Beaked whale investigation

In the summer of 2002, there were several strandings of Sowerby's beaked whales off the southern coast of Pico Island, Azores. In early 2003, after many months of negotiations, the Department of Oceanography and Fisheries (DOP) of the University of the Azores and the Marine Connection, finally arranged for a necropsy and CT Scans to be carried out on the heads of three of the stranded whales. The charity had to forcefully push for this work to be carried out as Dr. Santos from DOP had initially stated that the whale heads had been sent to the Bahamas for examinations. Closer investigation by the Marine Connection however proved that the heads had never been sent to the Bahamas but were in fact being stored in freezers in University premises.

The Marine Connection felt it was vital to ascertain if the strandings were linked in any way to acoustic testings that had been conducted in relation to one of the University of Azores/DOP projects. This involved the development of an Autonomous Underwater Vehicle (AUV) and Autonomous Surface Vehicle (ASV). Dr Darlene Ketten, an expert on acoustic trauma, finally flew to the Azores to carry out the scans, which were witnessed by Marine Connection Director of Operations, Liz Sandeman. CT scans and necropsies carried out on two of the Beaked whale heads indicated no evidence of acoustic trauma to the brain case and auditory canals by visual hemorrhaging. It was not possible to make MRI scans (the three dimension scanning process), of the frozen heads as the animals bodies had repeatedly collided with the rocky coastline before recovery and contained too many small particles of rock, which would have caused damage to the hospital scanning machinery. Unfortunately, no soft tissue samples (lung, liver or heart) had been kept by the scientists of DOP, making further study impossible. These samples would have been relevant for a more thorough and conclusive analysis of acoustic trauma as is the accepted practice in such scientific investigations.

Further investigations by the Marine Connection showed that a total of six beaked whales stranded during the same period of the Sowerbys beaked whale strandings. Over a two month period in 2003, there were many further strandings around the Azores, including a Blainville's beaked whale mother and calf, neither whale appeared to have any exterior wounds or cranial fractures when discovered and were in good body condition. It was confirmed by an marine mammal acoustic expert that the stranding of this mother and calf were related to acoustic trauma.

Beaked whales can dive up to 6,230ft (1,899m) under the surface and hold their breath for 85 minutes - an astonishing achievement! Scientists studying the whales behaviour have confirmed that the dives constitute the deepest confirmed dives reported from any air-breathing animal. The animals studied were Cuvier's beaked whales and Blainville's beaked whales reported from any air-breathing animal. This extreme deep-diving behaviour is of particular interest since beaked whales stranded during naval sonar exercises have been reported to have symptoms of decompression sickness." The study, reported in The Journal of Experimental Biology, suggests that it is not deep dives that leave the whales at risk of decompression sickness but repeated dives to shallower depths of 100-250ft.