© Institute of Marine Research, Norway
Smashed and dead cold-water coral fragments in a trawling ground on the Norwegian continental shelf.
More information
Many fishing practices are extremely destructive to delicate habitats - particularly vital fish breeding grounds like coral reefs and seagrass meadows.
For example:
For example:
- Bottom trawling: Industrial trawlers once avoided coral reefs and other rocky regions of the ocean floor because their nets would snag and tear. But the introduction of rockhopper trawls in the 1980s changed this. These trawls are fitted with large rubber tires or rollers that allow the net to pass easily over any rough surface. The largest, with heavy rollers over 75cm in diameter, are very powerful, capable of moving boulders weighing 25 tonnes. Now, most of the ocean floor can be trawled down to a depth of 2,000m.
These trawls - whose use is now widespread - are extremely damaging. In an experiment off Alaska, 55% of cold-water coral damaged by one pass of a trawl had not recovered a year later. Scars up to 4km long have been found in the reefs of the north-east Atlantic Ocean. And in heavily fished areas around coral seamounts off southern Australia, 90% of the surfaces where coral used to grow are now bare rock. When covered with marine life, these seabed areas provide habitat for juvenile fish and other species. Like removing forest, removing this cover decreases the area available for marine species to live and thrive in.
