Pockets of the small, silvery fish were found first at Anne Port and Archirondel and, more recently, at Beauport.
The appearance of the dead and decaying fish alarmed many Islanders, who reported the finds to the marine biology section of the Société Jersiaise.
But yesterday, marine and coastal manager Paul Chambers said that samples of the dead eels examined by Environment Department scientists appeared healthy and well fed, with no evidence of disease, contamination, parasites or a red tide event – a phenomenon caused by algal blooms.
‘Whatever happened happened all at once to one species in one particular area,’ he said, adding that an event like a red tide would have affected other species.
The sand eels are a shoaling species and would have been travelling together en masse.
Dr Chambers said the definitive cause of their mass death may remain a mystery but lightning strikes from storm activity around the Island were a ‘distinct possibility’. ‘They move around in the hundreds of thousands so we certainly cannot rule out the possibility of a lightning strike,’ he said.
Sand eels have also been seen to die in large numbers during heat waves, he added, as they bury themselves in the sand at low tide. When the sand gets too hot, oxygen is driven out and the tiny fish are essentially cooked.
While Jersey enjoyed a pleasant, sunny weekend, recent temperatures have not been high enough to support that explanation, Dr Chambers said.
‘It is slightly odd and it does cause alarm but these things do occur naturally from time to time,’ he said. ‘As a department, we are confident it was not caused by anything we need to be concerned about.’
Environment will continue to the monitor the situation, however.
