Trawlers damaging precious sponge beds

Deep-sea trawling is damaging the UK’s sponge beds and threatening a potential source of medical cures, scientists have warned.

Researchers in Edinburgh said deepwater sponges were “treasure chests” that were being worn away by fishing and engineering works.

Ocean sponges from shallower waters have already proved effective at combating diseases like cancer.

Scientists believe the deepwater variety will be equally valuable.

Trawlers work by pulling large nets close to or along the sea floor to catch fish like cod.

According to a study led by a team at Heriot-Watt University, sponge grounds dating back up to 9,000 years are being destroyed in the process.

‘Causing carnage’

Murray Roberts from the Centre for Marine Biodiversity and Biotechnology said: “People might think of natural sponges as just a bit of a bath time luxury, but they are potentially vitally important to future medical developments.

“We already know that some sponges contain substances which are being used to treat cancers, but there are so many other species in our own UK and Scottish deep waters that we simply don’t know about.

“We found a hundred sponge species at Scotland’s only inshore cold-water coral reef near Mingulay, and over the next few years we will be investigating other sites around Scotland where we hope to find many more.

“But meanwhile we have also shown that deepwater bottom trawling is causing carnage among these slow-growing but potentially invaluable colonies.”

The expert said sponges grew fixed in place and had to compete for space with many neighbouring animals.

This means that over millions of years they have evolved to include many chemicals – known as secondary metabolites – to defend themselves.

It is these complex chemicals that are showing promise as a new generation of drugs, Mr Roberts said.

He added: “Appreciation of deep sea sponge grounds and consideration of them in conservation and management decision-making is only just beginning.”

The report Deep Sea Sponge Grounds: Reservoirs of Biodiversity is being unveiled at the European Marine Biology Symposium at Heriot-Watt University.

Seafish is a company that works across all sectors of the seafood industry.

Phil MacMullen, Head of Environmental Responsibility at Seafish, said:

“Sponge beds are enormous, very dense areas, which are not targeted by fishermen, in fact, exactly the opposite is true.

“Fishermen will avoid these areas at all costs because it is very difficult to remove the sponges from the nets, the nets themselves become damaged and the spines are painful for fishermen

“Seabed mapping means that fishermen have a good knowledge of the seabed.

“These huge sponge bed swathes are very easy to identify and avoid.”