Larger biomass of targeted reeffish in no-take marine reserves on the Great Barrier Reef, Australia

1. An expansion of no-take marine reserve zones of Australia's 348 000 km(2) Great Barrier Reef (GBR) Marine Park from 4.6% to 33.4% of the park area is proposed in 2004. However, limited evidence currently exists that no-take marine reserves on the GBR have increased abundance of reef fish targeted by fisheries. This study provides such evidence for inshore reefs of the GBR. 2. Underwater visual surveys were used to estimate the effect of no-take reserves on abundance of species targeted by hook-and-line fisheries around the Palm, Whitsunday and Keppel Islands, spanning 600 km of the length of the GBR. The reserves had been zoned 'no fishing' for 14yr. 3. Densities of Plectropomus spp. and Lutjanus carponotatus, both targeted by fisheries, were much higher in protected zones than fished zones in two of the three island groups. Plectropomus spp. were 3.6 and 2.3 times more abundant in protected than fished zones of the Palm and Whitsunday island groups. L. carponotatus were 2.3 and 2.2 times more abundant in protected zones than fished zones of the Whitsunday and Keppel island groups. 4. The biomasses of Plectropornus spp. and L. carponotatus were significantly greater (3.9 and 2.6 times respectively) in the protected zones than fished zones at all three island groups. 5. Legal minimum sizes of Plectropomus spp. and L. carponotatus are greater than or equal to38cm and 25cm TL respectively. There were significantly higher densities and biomasses of Plectropornus spp. > 35 cm TL (density: 3.8 times; biomass: 5.1 times) and L. carponotatus > 25 cm TL (density: 4.2 times; biomass: 5.3 times) in protected zones than fished zones at all three island groups. 6. No significant difference in abundance between protected and fished zones was found for two species not captured by fisheries (Siganus doliatus and Chaetodon aureofasciatus), and there were no significant differences in benthic characteristics between protected and fished zones. 7. Results suggest that no-take marine reserves have increased stock biomass of targeted fish species on inshore GBR reefs. Copyright (C) 2004 John Wiley Sons, Ltd.