Fish factory. This redfish and his friends benefit from deep-sea coral reefs in the North Atlantic that are threatened by trawling.

Bulldozing Deep-Sea Reefs

Deep-water coral reefs off the coasts of Ireland and Norway, only recently explored, have already been extensively damaged by commercial trawling for fish, according to a new report. The researchers urge conservation measures to safeguard the reefs, which provide havens for marine life and valuable spawning grounds for fisheries.

Tropical coral reefs are well-known for their astounding biodiversity, but coral reefs also exist in the frigid waters of the Northeast Atlantic, much deeper down, at the edges of the continental shelf. Only in the past several years have researchers begun to learn much about these reefs. Unlike their shallow-water cousins, which live symbiotically with photosynthetic organisms, these corals survive in the dark, using tentacles to feed on tiny crustaceans called copepods. Whereas deep-water reefs are built of only a few kinds of corals, they provide habitat for many hundreds of other species, including commercially valuable fishes.

Now, videotapes taken with a submersible off Norway reveal that damage from commercial trawlers has left reefs there looking like a clear-cut forest, marine biologist Jason Hall-Spencer of the University of Glasgow, United Kingdom, and two colleagues report in the 7 March issue of the Proceedings of the Royal Society of London B. The trio also found large chunks of coral in the catch hauled up by two French vessels fishing off West Ireland. Radiocarbon dating of these fragments indicates the reefs are at least 4500 years old. Although only five of 229 hauls included substantial amounts of coral, Hall-Spencer says the extremely slow-growing coral can't recover from frequent trawling.

The study provides "unequivocal evidence that trawlers are devastating this ecosystem," says marine biologist Callum Roberts of the University of York, U.K. Hall-Spencer says he has no doubt that protecting the reefs will be discussed when the European Union looks to revise its common fishing policy later this year.

Related links
Hall-Spencer's page
Fact sheet on the Darwin Mounds reef area, U.K.
More on related research by Hall-Spencer

Posted in Environment