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UK Strandings Lead to Murky Picture of Naval Activity

Effects of Noise on Wildlife, Ocean Add comments

A week after the UK’s worst dolphin stranding since 1981, reports from locals and the UK Navy are conflicting. Two weeks of live-fire exercises were wrapping up in the area over last weekend, with the Navy first claiming to have concluded those exercises Sunday afternoon, then saying that in fact the last live-fire took place far offshore on Friday, with a mid-frequency submarine-hunting sonar used on Thursday. However, local Falmouth Coast Guard personnel report heavy Naval activity through Sunday afternoon in Falmouth Bay. And, Nick Tomlinson, a local fisherman working 12 miles offshore, experienced a most dramatic blasts than he has felt in the 35 years he has been working the waters off the Cornish coast. “I’m used to the big military guns going off but this was something different – bang, bang, bang, very close, very loud. The vibrations went through the boat and up through my backbone. The whole boat was shuddering.”
(Press reports are not clear on whether Tomlinson heard this on Sunday or Monday.) On Monday, dolphins were found trapped in two different estuary rivers, and milling unusually close to shore near Falmouth. Dead dolphins had mud in their lungs and stomachs, likely taken on while floundering in low estuary tides. The British Divers Marine Life Rescue (BDMLR), which co-ordinated the rescue of several dolphins, said they received reports from the public that an explosion took place at sea over the weekend. Such an explosion could have panicked the dolphins – who were away from their natural deep water habitat – and sent them up the river to shallow waters. “It does not mean that the Navy is to blame, but it would be naive of us to ignore the activity that has been going on,” said the BDMLR.

The main stranding sites were in the Perculi River, right side of image, with other dolphins also caught
in the Helford River, bottom left, and some dolphins milling unusually near to shore in Falmouth as well. 
All of these estuaries could have offered quiet refuge from any loud noises
occuring in Falmouth Bay or the open ocean nearby.
Image courtesy Google Maps

BDMLR chairman Alan Knight, said: “The fact that they have beached in four separate sites is very unusual. It indicates to me that there is some kind of disturbance.”  For the first week, statements from the Royal Navy neglected to mention whether mid-frequency sonar use during the exercises; a spokeman admitted to a reporter who asked about it that she was not sure and would have to check. Navy statements have said only that no low-frequency sonar was in use, and that a short-range high-frequency mapping sonar was being used on Sunday and Monday 12 miles offshore; the mapping sonar is unlikely to have caused a panic that far away, as high-frequency sound dissipates at short range. A week later, the UK Navy admitted that a “dipping” version of the mid-frequency sonar (dangled from a helicopter) had been used on the Thursday before the strandings, spurring speculation that the dolphins may have entered Falmouth Bay at that point, and been disoriented for several days. It seems more likely that, whether chased into the bay by the dipping sonar or not, some dramatic event on Sunday or Monday morning was more directly to blame, sending the dolphins into two estuaries where they floundered and died. Two alternatives to the idea that noise chased them upstream have become less likely as more information appears: no orcas were seen in they bay, making it unlikely a pod could have chased the dolphins in three directions at once, and while there were many fish feeding on unusually large algae blooms in the area, most dead dolphins had no fish in their stomachs, suggesting they were not feeding when they were in the estuaries. Sources: Telegraph, 6/10/08 [READ ARTICLE] Daily Mail, 6/11/08 [READ ARTICLE]


One Response to “UK Strandings Lead to Murky Picture of Naval Activity”

  1. » Blog Archive » 2008 UK stranding linked to Navy exercises Says:

    […] around Falmouth Bay, as several days of Naval exercises involving over 30 ships wound down (see AIEnews coverage at the time).  A four-year study (read it online) has  concluded that unspecified Naval […]