You are in > Home > News & Events > News > Mystery Corkscrew Seal Deaths: "Boats Are To Blame"

Mystery Corkscrew Seal Deaths: "Boats Are To Blame"

Scientists investigating the mysterious spate of fatal "corkscrew" injuries to seals believe that boat propellers are the most likely cause.

The preliminary findings from a report by researchers at the University of St Andrews' Sea Mammal Research Unit (SMRU), produced in conjunction with the SAC Consulting Veterinary Division's Wildlife Unit in Inverness, reject previous claims that the unusual fatalities marked with spiral-shaped lacerations were caused by sharks.

SMRU and SAC's vets, in collaboration with the RSPCA in England, set out to investigate the carcasses of seals washed up on the east coast of the UK over the summer months. The SAC unit carried out post mortems on a number of seal carcasses.

Their initial reports conclude that the injuries were most likely caused by the ducted propeller systems on ships operating in shallow coastal waters.  The findings eliminate most other possibilities including the effects of fisheries, deliberate mutilation, the effects of illegal traps and predation by killer whales or sharks.

Since their initial discovery in Spring  2010, the team has investigated of the 33 carcasses washed up with a single, smooth-edged cut starting at the head and spiralling around the body.

The vet in charge of the SAC-led Scottish Marine Mammal Strandings Scheme, Dr. Andrew Brownlow said: "The lacerations extend right through the skin and blubber, in many cases peeling these layers from the skeleton. This suggests that a mechanical device with great inertia is both cutting and spinning the seal through the water column.

"Work done by SMRU on scale models showed that these injuries are entirely consistent with animals being sucked through ducted propellers with a relatively blunt blade but a very large amount of power behind it. What we don't know yet is the magnitude of this problem and how many cases we are simply missing because they are never found."

Future studies by SMRU and SAC, dependent upon funding, will include further research that might provide a solution to the problem, especially as it is possible that this type of injury may be more widespread than the existing cases suggest.

Professor Ian Boyd, Director of SMRU and the Scottish Oceans Institute commented, "We are all very concerned to find out why this has happened. It is slightly suspicious that we have observed these injuries in places where researchers with appropriate knowledge are most likely to find them, which leaves me thinking that we might only be seeing the tip of the iceberg.

"But we hope that the current observations are an isolated case reflecting very specific circumstances that, once understood, can be avoided in future through simple changes to the operational procedures of the vessels involved."

Keep up to date with developments at the SAC Seal Lesions Blog: http://www.sac.ac.uk/consulting/services/s-z/veterinary/scottishmarinestranding/sealblog/

Comments

blog comments powered by Disqus