A survey of the world's reefs and submerged mountains has revealed widespread damage from deep-sea trawling
Deep-sea trawling is devastating corals and pristine marine habitats that have gone untouched since the last ice age, a leading marine biologist has warned.
A survey of the world's reefs and seamounts – giant submerged mountains that rise more than a kilometre above the seabed – has revealed widespread damage to the ecosystems, many of which are home to species unknown to science, said Jason Hall-Spencer at Plymouth University in the UK.
Hall-Spencer, a researcher involved with the Census of Marine Life, a worldwide project to catalogue life in the oceans, called for the establishment of an international network of marine reserves where deep-sea trawling was banned.
Deep-sea trawlers use giant, heavy-duty nets that are dragged over the seafloor at depths of more than a kilometre. The nets are fitted with rubber rollers called "rock hoppers", which destroy the corals that provide habitats for fish and other marine organisms.
The technique was developed for use in shallow waters with smooth sea floors, but as fish stocks dwindled and technology improved, fishing fleets began using the nets in much deeper waters.
Hall-Spencer said marine biologists have surveyed fewer than 1% of an estimated 50,000 seamounts in the world's oceans.
"Our research visits have revealed pristine coral reefs and many species that are brand new to science," Hall-Spencer said. "Over the past five years, these surveys have also worryingly revealed that all over the world, deep-sea habitats are suffering severe impacts from bottom trawling.
"It doesn't matter what ocean you go to, these habitats are being trashed by international fishing fleets. What is urgently needed is a network of protected areas where any type of fishing gear that involves dragging equipment across the sea bed is banned."
Each trawler typically crisscrosses an area of ocean around 33 kilometres square. Among the most threatened sites are cold water coral reefs in temperate regions, which are still being discovered. Sizeable areas off the west coasts of Scotland and Ireland have been severely damaged, Hall-Spencer told the annual meeting of the American Association for the Advancement of Science in San Diego today.
"I've seen areas that are pristine and untouched since the ice age and these are worth protecting," he said. "The coral is white or bright orange, and there are fans as high as your chest. These are particularly vulnerable to trawling. Unlike shallow water reefs, they don't have to be strong enough to withstand large waves and they can't cope."
The Norwegian government has banned deep-sea trawling over the Røst reef, the biggest cold-water reef in the world, which was only discovered in 2002. The three kilometre-wide strip is teeming with life and stretches for almost 40 kilometres at a depth of 450 metres. Similar bans are in place at a number of other sites around the world, but more are needed, Hall-Spencer said.
Copyright Speakers Corner 2017