Grey snappers: on the up in marine reserves and nearby fishing grounds in St. Lucia. Credit: © C. Roberts

Banning fishing in some areas boosts catches in others, say researchers. Fisheries in the Caribbean and Florida have become more productive since marine reserves were established - despite fishermen having fewer areas to fish in1.

The idea that such reserves help fishing has been controversial. "There hasn't been good evidence that reserves will benefit surrounding fisheries," says Callum Roberts, a conservation researcher at the University of York, UK. He thinks his latest research provides that evidence.

Roberts and colleagues studied a coral reef off the Caribbean island of St Lucia where a network of small marine reserves was set up in 1995. They found that, since then, stocks in the reserve have quadrupled, and those in the neighbouring sea have trebled, reversing a previous decline. Fishermen are spending less time on the water, but are catching more fish.

Once-sceptical reef fishers are now enthusiastic about reserves. Credit: © F. Gell

The team also looked at an estuary near Cape Canaveral in Florida that became off-limits to people in 1962 to protect the rocket-launching site. The waters around the reserve "have become a honey-pot site for catching spectacular fish", says Roberts. More record-sized fish are caught here than in all the rest of Florida, he says, and the sizes are continuing to grow.

Some fishermen doubt the benefits of protected areas. "Reserves take the focus from where it should be, which is good conservation throughout the fishery," says Rick Farren, communications director of the Coastal Conservation Association Florida, an anglers' group "adamantly opposed" to marine reserves.

But the tide seems to be turning against this viewpoint. Reserves "have captured the imagination of a great many people", says John Ogden, director of the Florida Institute of Oceanography in St Petersburg. The new study is "a hard case for recreational fishers to answer", he adds.

Reserve judgement

In the United States, marine reserves have political as well as academic momentum - a scheme to set up protected areas nationwide has won government support. "The idea is snowballing, the more we study reserves, the more compelling the arguments for them are becoming," says Roberts.

Spanish grunt: another large fish returning to St. Lucia's reefs. Credit: © C. Roberts

Fisheries are traditionally managed with limits on the amount and size of fish caught and on the equipment used to catch them. But these have failed to arrest the drastic decline in catches around the world, partly because limits tend to get stretched during political haggling.

Many researchers argue that marine reserves are crucial to restoring fisheries. Reserves conserve the entire marine ecosystem in addition to fish stocks, they say, and the complete protection they provide is an insurance policy against management failures elsewhere.

But the ultimate goal must be to care for the land and ocean as a whole, says Ogden. "The problems in the ocean are about a whole lot more than fishing," he says, pointing out that pollution from the land probably does an equal amount of damage to the marine environment.