Two UK environmental and research organizations that were monitoring whale activity during a recent NATO naval exercise report that minke whales were seen fleeing along the surface while their hydrophones were picking up loud mid-frequency active sonar signals.  Observers from the Hebrides Whale and Dolphin Trust saw “two minke whales within an hour displaying unusual and worrying behaviour. At the same time they heard military sonar on the hydrophone – sometimes so loud that they could not keep the headphones on. The whales were both moving in the same direction at high speed, regularly leaping clear of the water. This behaviour, known as ‘porpoising’, is more typical of dolphins and rarely seen in undisturbed whales.”

Porpoising minke whale. Credit: HWDT

Nienke van Geel, HWDT’s Biodiversity Officer said “Seeing minke whales porpoising many times successively is very unusual. Both whales moved very fast, too fast for us to keep up with them to try to take identification pictures. We estimated they were traveling at least at 15 knots. Our research has already shown a decline in minke whale sightings in the last few years, so we’re worried about anything that might adversely affect the population.” The incident is reported on in three posts from the HWDT’s colleagues, the Whale and Dolphin Conservation Society (WDCS).  The first includes the initial report of the incident, the second details the situation more fully and stresses the need for the UK Navy to conduct fully environmental assessments as the US Navy has begun to do at home, and the third clarifies that the US Navy should be, according the the US Marine Mammal Protection Act, applying for permits for sonar activities in UK waters, though it currently only does so for training in US waters.