While predatory fish are key to the Caribbean's ecosystem and coastal economy, researchers have worryingly found that 90 per cent have been wiped out by over-fishing. But experts say there is hope for Caribbean reefs yet, as they have identified large reefs, known as 'supersites', which can support huge numbers of predatory fishes. If the dwindling fish species are reintroduced, they could help repair the damage inflicted by over-fishing.
'A live shark is worth over a million dollars in tourism revenue over its lifespan because sharks live for decades and thousands of people will travel and dive just to see them up close,' said study coauthor and marine biologist Dr Abel Valdivia.
'There is a massive economic incentive to restore and protect sharks and other top predators on coral reefs.'
The University of North Carolina team's work suggests that supersites - reefs with many nooks and crannies on their surface that act as hiding places for prey - should be prioritised for protection.
Other features that make a supersite are the amount of available food, size of the reef and proximity to mangroves.
'On land, a supersite would be a national park like Yellowstone, which naturally supports an abundance of varied wildlife and has been protected by the federal government,' said coauthor and marine biologist Professor John Bruno.
The team surveyed 39 reefs across the Bahamas, Cuba, Florida, Mexico and Belize to determine how many fish had been lost.
They compared fish biomass on pristine sites to fish biomass on a typical reef.
They then estimated the biomass in each location and found that 90 per cent of predatory fish were gone due to over-fishing.
What they didn't expect to find was a ray of hope - a small number of reef locations that, if protected, could help the predatory fish populations recover.
'Some features have a surprisingly large effect on how many predators a reef can support,' said study coauthor Dr Courtney Ellen Cox.
For example, researchers believe that the Columbia Reef within the fisheries closures of Cozumel, Mexico, could support an average of 10 times the current level of predatory fish if protected.
Not long ago, large fishes were plentiful on coral reefs, but are now largely absent due to targeted fishing.
Today, predators are larger and more abundant within the marine reserves than on unprotected, over-fished reefs.
But even some of the marine reserves have seen striking declines, largely due to lack of enforcement of fishing regulations.
The bottom line is that the protection of predatory fish is a win-win from both an environmental and an economical perspective, explained Professor Bruno.
Earlier this month, the World Bank said that global profits from fishing could grow by tens of billions of dollars if depleted fish stocks were allowed to recover, bolstering the livelihoods of millions of people and feeding the world's growing population.
Over-fishing costs more than $80 billion (£65 billion) a year in lost revenues as dwindling supplies require extra effort to find and catch increasingly scarce fish, according to the study by the World Bank.
Millions of people depend on fish to survive, and fish will be vital to feeding the world population that is predicted to reach 9.7 billion people by 2050, the United Nations has said. Due to over-exploitation, however, trawlers must sail further and longer to catch fish, leading to higher costs and lower profits, the World Bank said in a study titled 'Sunken Billions Revisited.'