But new research suggests that fishing bans help control starfish outbreaks on the world's largest reef system.
Hugh Sweatman, of the Australian Institute of Marine Science in Townsville, Australia, used surveys of crown-of-thorns starfish on the Great Barrier Reef and overlaid them with the locations of no-fish zones.
The first no-fish zones, covering 4.5 percent of the reef, were established in 1989.
"The frequency of outbreaks on reefs that were open to fishing was 3.75 times that on no-take reefs in the mid-shelf region of the Great Barrier Reef where most outbreaks occur," Sweatman said.
Outbreaks of the starfish include hundreds of thousands of the coral-chompers covering miles of reef at a time. Once they polish off the corals on one reef, the starfish produce larvae that float to the next reef, propagating the outbreak.
Exactly how fishing bans reduce these outbreaks is not clear. Evidence that the protected fish control the starfish directly by eating them is scant, Sweatman said.