A new United Nations report says the fishing practice known as bottom trawling is destroying irreplaceable coral and underwater mountains, and it says the damage cannot be repaired.
Some commercial trawlers drag large nets made of chains across the ocean floor to catch fish that live far beneath the surface.
The scientists who wrote the report say bottom trawling is tearing up coral thousands of years old. They say the coral is home to numerous species of fish and other sea life, including some fish species that have yet to be identified.
The experts say the damaged coral can never grow back.
The U.N. released the new report as it considers a worldwide ban on bottom trawling in waters not currently covered by international rules.
Some information for this report was provided by AP and Reuters.