They also provide a habitat for fish and other species of ecological and commercial interest, such as orange roughy, swordfish, tuna, sharks, turtles and whales.

UNESCO: MEDIA SERVICES

Bottom-trawling's knock-on impacts are best illustrated by the plight of the deep-sea fish, the orange roughy (also known as slimeheads) whose populations have been reduced by more than 90%, according to marine scientists.

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Last year, the company stopped selling seven other species on the Greenpeace red list including Atlantic cod, Chilean sea bass and orange roughy, says Jeff Lyons, Costco's senior vice president of fresh foods.

WSJ: Guidelines for Eating Sustainable Seafood

Among the species threatened by bottom fishing is the orange roughy, which lives for more than a century and takes decades to reach sexual maturity: in those gloomy depths, creatures aren't used to sudden events.

ECONOMIST: Marine conservation