Mystery of thousands of dead sand eels

Monday 04 June 2018

Islanders were left scratching their heads over the weekend after thousands of dead sand eels mysteriously washed up on Jersey’s east coast.

The fish – a 4-9cm favourite of the island’s puffin population – were found scattered across Archirondel and Anne Port on Friday afternoon, one day after gulls were spotted “gorging” on them at Les Écréhous.

Société Jersiaise’s Marine Biology Section launched an investigation after receiving reports of the unusual scenes, but said there was no obvious cause of death – specimens taken from two areas were found to be “healthy with food in the guts… and gills in good condition.”

“What can have caused this? This is a difficult one to answer. The die off seems to be a species-specific (and only juveniles) single event. The fish seem healthy with no obvious sign of disease or starvation. This suggests it is not a pollution event or due to illness. Toxicity from 'red tides' has been a cause of mass sand eel mortality in the UK but this is unlikely here as there is no sign of red tide algae concerned and it is also generally a phenomenon of estuaries,” researchers said.

But some islanders have suggested that the answer may not come from the sea, but the sky: last week’s dramatic lightning storm.

“A strike directly onto a shoal of sandeels (or onto the sandbank in which they were sheltering at low water) could possibly cause this. A similar mass die off happened in Jersey many years ago (we can't remember the date) also occurred following thundery weather,” the Société team said.

However, they’re refusing to rule out other causes at this stage and are inviting islanders to submit their thoughts and observations via their website.

Lead photo: Thousands of sand eels - often eaten by puffins (inset - Steve Garvie/Wiki) and gulls - mysteriously washed up at Archirondel on Friday. (Claire Stevens)