Drugs by Glastonbury festival-goers could impact endangered eels

Hyperactive eels

The European eel was once common in most UK rivers. But in recent decades, their numbers have plummeted, declining by more than 95%.

The eel’s migratory life cycle makes it particularly vulnerable. Although it’s not yet known exactly how the eels manage their epic journey, the adults will leave rivers all over Europe and make their way to the Sargasso Sea off the east coast of the United States.

Here they mate and lay their eggs before they die. The eggs then hatch and the young eels will cross the Atlantic again, although they have never made this trip before. It is at this stage that they are most at risk.

Historically, large numbers of young glass eels were harvested as they attempted to swim upriver. Today, with legal trade now much more restricted and regulated, illegal trade is actually the biggest wildlife crime in Europe, as millions of baby eels are caught and smuggled into Asia.

For those who survive the return trip, many now find rivers blocked by dams and weirs. It seems that, in some populations at least, European eels are now also dealing with being bathed in illegal drugs that would impact this extraordinary life cycle.

Previous studies have shown that low levels of cocaine in waterways can make European eels hyperactive in the laboratory. There was also evidence that it could lead to muscle loss, which could have a significant effect on their epic journey into adulthood.

This new study found that after the Glastonbury Festival, levels of cocaine detected in downstream water were at levels high enough to potentially cause a similar effect for native fish.

Dr Christian Dunn, lead author of the paper, says: ‘Our main concern is the environmental impact. This study identifies that drugs are being released at levels high enough to disrupt the European eel’s life cycle, potentially derailing conservation efforts to protect this endangered species.

“Education is key on environmental issues, just as people have been made aware of plastic pollution issues, and Glastonbury has made great efforts to become plastic free. We also need to raise awareness about drug and pharmaceutical waste – these are hidden but potentially devastating pollutants.

The researchers recommend creating reedbeds as a natural filtration system, in which the wetlands help treat sewage and potential contaminants escaping from the festival.

Jan G. Gilbert