Areas of coral reef that are completely closed to fishing vessels are significantly more effective at conserving sharks than areas in which shark fishing is temporarily banned.
New research by scientists at James Cook University's School of Marine and Tropical Biology, which has recently been published in the journal Current Biology, says that an order of magnitude fewer sharks are found on fished reefs compared to those where fishing is banned.
Managed no-entry zones (NEZ), which make up about 1% of the Great Barrier Reef, had an order of magnitude more sharks than areas in which shark fishing was allowed.
Harder to enforce no-take zones (NTZ), in which shark fishing is banned, offered almost no protection to shark populations.
Sharks are important apex predators on coral reefs and are believed to play key roles in maintaining healthy reef ecosystems.
However, increasing fishing pressures are leading to overexploitation, and existing methods of conservation, which are typically based on no-take marine reserves, do not appear to be work working, the authors state.
"Population viability models of whitetip and gray reef sharks project ongoing steep declines in abundance of 7% and 17% per annum, respectively.
"These findings indicate that current management of no-take areas is inadequate for protecting reef sharks, even in one of the world's most-well-managed reef ecosystems.
"Further steps are urgently required for protecting this critical functional group from ecological extinction."
For more information see the paper: Robbins WD, Hisano M, Connolly SR, Choat JH (2006) - Ongoing collapse of coral-reef shark populations. Curr Biol. 2006 Dec 5;16(23):2314-9.