Sarah Dolman sarah.dolman at wdcs.org
Wed Jun 17 07:14:59 PDT 2009



A report on the common dolphin mass stranding event that occurred in
Cornwall, UK, in June 2008 has now been released by Defra (UK
Government).  The report link is:-



An associated news piece may also be of interest:





Naval exercises could have contributed to the mass stranding of 26
dolphins on the Cornish coast a year ago, a scientific report found


The pod of dolphins beached themselves at four separate locations around
the Percuil river near Falmouth in June last year after Navy exercises
in the area involving surface ships and a submarine.


At the time, rescuers said they believed the worst mass stranding of the
marine mammals in UK waters was the result of the dolphins being
panicked by an underwater disturbance.


According to the today's study led by Zoological Society of London (ZSL)
researchers, sonar used in the exercises was "highly unlikely" to have
directly caused the dolphins to beach themselves.


But the activities of the Navy could have been a contributing factor in
pushing the marine mammals close to shore and put them at risk of


Dr Paul Jepson, of ZSL, said: "We don't have definitive information but
we've ruled out everything else, and it's possible that something in the
naval exercises caused the mass stranding."


The study said a definite cause for the stranding could not be found,
although the dolphins could have reacted to a "trigger" event or
suffered an "intrinsic error of navigation".


The research said the common dolphins were unusually close to shore and
at a greater risk of beaching themselves - possibly because they were in
unfamiliar waters.


Naval activities such as the use of sonar for anti-submarine training
could have been a factor in the dolphins, which are sensitive to
underwater sounds, coming closer to shore.


Natural behaviour such as foraging for food could also have played a


The ZSL researchers said information supplied by the Ministry of Defence
(MoD) under the Freedom of Information Act showed several days of
"mid-frequency sonars for anti-submarine warfare training" ended some 60
hours before the stranding.


A "short-range side-scan sonar" for sea-bed mapping trials was used by
the Navy the day before the dolphins beached themselves, but the
technology is common and has not been implicated in strandings, the
study said.


As a result the use of underwater sonar in the Navy exercises was
"highly unlikely to have directly triggered the mass stranding event",
but the researchers believe other parts of the exercises could be to



The study also ruled out other potential causes including disease,
poisoning, attacks by killer whales or bottlenose dolphins and even
earthquakes as the reason for the mass stranding - only the fourth

recorded in England since 1913.


In the wake of the report, the Whale and Dolphin Conservation Society
said it believed that as all other potential causes had been ruled out,
the military was to blame of the strandings.


Sarah Dolman, ocean noise campaigner for WDCS, said: "The post-mortem
results have shown us that those dolphins that died were healthy animals
prior to stranding.


"Something frightened them ashore, way up inside the river system, where
this species in not generally known to go.


"The unusual behavioural response of all these groups of otherwise
healthy animals was triggered by something.


"An 'error of navigation' would not lead this many dolphins to strand,
and other groups to behave in such an unusual manner, on the same
morning - but over a distance of 20km."


She called on the Ministry of Defence to conduct transparent
environmental assessments of its exercises to see what effect they were
having on marine life, and to suspend use of sonar once a stranding

occurs until rescued animals are out of danger.


The mass beaching in Cornwall was one of two unusual stranding events of
cetaceans - the group of marine mammals including whales, dolphins and
porpoises - last year.


No cause could be found for the other event, in which a number of
long-finned pilot whales and various species of beaked whale were found
stranded in Scotland, Wales and Ireland over a three-month period at the

beginning of 2008.


The annual report for 2008 from the UK Cetacean Stranding Investigation
Programme, also published today, revealed the number of dead and
stranded whales, dolphins and porpoises increased by 6.2% on the
previous year.


Some 583 cetaceans were reported to the programme, of which 485 were
found stranded and dead, 81 were live strandings and 17 were found dead
at sea.


The most common species reported were harbour porpoises which were
mainly found to have died of starvation, disease, attacks by bottlenose
dolphins or as a result of being accidentally caught by fishermen, and
short-beaked common dolphins, which mostly died as a result of stranding
themselves live, the report revealed.


Sarah Dolman

WDCS Noise Pollution Campaign Manager

Sarah.dolman at wdcs.org


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