Washington, June 24 : A new study of Australia's Great Barrier Reef has revealed that marine reserves in which fishing is completely banned, can lead to very rapid comebacks of the fish species most prized by commercial and recreational fisheries, with the prominent example being the coral trout in Australia.
The new findings come from a joint study by scientists from James Cook University and the Australian Institute of Marine Science.
The researchers found in most cases that coral trout-the major targets of commercial and recreational hook-and-line fisheries in Australia-bounced back in no-take reserves compared to fished sites in two years or less.
"We were surprised that we documented increases in coral trout density of 31% to 68% in such a short time," said study author Garry Russ of James Cook University in Queensland.
According to Russ, others have seen such rapid increases in smaller-scale studies, usually at one or a few small reserves.
"The big surprise was that we detected a consistent, rapid increase in multiple large reserves spread over 1000 km offshore and 700 km inshore," he said. "This represents a positive and unprecedented response to reserve protection," he added.
In the new study, the teams used underwater visual census to survey reef organisms in new coral reef reserves and in control areas that remained open to fishing before and again 1.5 to 2 years after the reserves were put into place.
They found that the coral trout numbers were significantly higher in no-take reserves than in sites that remained open to fishing in four of five offshore regions and two of three inshore regions of the Great Barrier Reef.
According to the researchers, the findings are probably due to decreased fishing mortality inside the new reserves, rather than increased fishing outside.
In inshore areas, where most recreational fishing occurs, the data showed increases in coral trout density inside reserves rather than decreases in adjacent fished areas after rezoning.
"Although preliminary, our results provide an encouraging message that bold political steps to protect biodiversity can produce rapid, positive results for exploited species at ecosystem scales," said Russ.