Russ et al., 2008:

"Here we report evidence, first, that the densities of the major target species of the Great Barrier Reef reef line fisheries were significantly higher in the new No-Take Marine Reserves (NTMRs), compared with fished sites, in just two years; and second, that the positive differences were consistent for multiple marine reserves over an unprecedented spatial scale (> 1000 km).

A team from James Cook University used underwater visual census to survey reef biota at eight sites in new coral reef NTMRs and in an equal number of control areas that remained open to fishing in three inshore island groups (0–30 km off the coast and spanning 4.5^o of latitude; see Figure S1 in the Supplemental data available on-line with this issue) before and again 1.5–2 years after implementation of the NTMRs (see Supplemental data). Concurrently, sites on 28 pairs of no take and open offshore reefs (30-200 km from the coast) in five GBRMP regions (spanning 7.5^o of latitude, see Figure S1) were surveyed 1.5–2 years after implementation by the Australian Institute of Marine Science. All offshore survey reefs were initially open to fishing but one reef per pair was declared a NTMR in mid-2004, while the other remained open to fishing. Inshore and offshore surveys used similar methods (see Supplemental data). After 1.5–2 years of protection, the density of the primary target of reef line fisheries, coral trout (Plectropomus spp.), increased significantly in inshore NTMRs in the Palm (p < 0.05) and Whitsunday (p < 0.001) Islands (+68 per cent and +65 per cent; Figure 1A). Changes were small and non-significant (+2 per cent and –6 per cent) where reefs remained open to fishing. Reefs in the other inshore region, the Keppel Islands, suffered extreme coral bleaching during March 2006 and coral trout density declined on both open reefs (–23 per cent) and NTMRs (–19 per cent). However coral trout density in NTMRs increased relative to open reefs in all three inshore regions, significantly so in the Whitsunday Islands and marginally so in the Palm Islands (Palms +65 per cent, p < 0.10, Whitsundays +75 per cent, p < 0.01 and Keppels +4 per cent, p >0.10). Offshore, average coral trout density was also higher in NTMRs than on open reefs in all five regions (Figure 1B), significantly so in four and marginally so in the fifth (Cairns +53 per cent, p < 0.10, Townsville +64 per cent,p < 0.01, Mackay +57 per cent, p < 0.001, Swains +3  per cent, p < 0.01 and Capricorn Bunkers +64 per cent, p < 0.001, (see Supplemental data).

These results are likely due to decreased fishing mortality inside new NTMRs in compliance with the new zoning [4], rather than increased fishing outside reserves. In inshore areas, where most recreational fishing occurs, our data show increases in coral trout density inside reserves rather than decreases in adjacent fished areas after rezoning, which cannot be explained by changes in fishing effort outside reserves. Offshore, where most fishing is commercial,some of the displaced fishing pressure would have been offset by the large declines in commercial fishing effort and catch over the period 2000-2006, caused mainly by the introduction of a catch quota system that coincided with the rezoning. In time, increased adult density in NTMRs may enhance recruitment both inside and outside NTMRs. The size and position of individual reserves in the network (see Figure S1 in the Supplemental data available on-line) and predictions of larval transport in the GBRMP [5] mean that there is considerable potential for export of coral trout larvae from NTMRs to fished areas. Such export would likely contribute to the long-term sustainability of the reef fisheries. Furthermore, coral trout, important predators of other fish, can influence reef fish biodiversity significantly [6]. The proportional increases in coral trout density in NTMRs were surprisingly consistent (density increased by 57-75 per cent in six of eight regions). The spatial scale of this positive response is unprecedented, being based on multiple offshore NTMRs in five regions up to 1000 km apart and multiple inshore NTMRs in three regions spread over 700 km.

Citation and/or URL

Russ, G.R., Cheal, A.J., Dolman, A.M., Emslie, M.J., Evans, R.D., Miller, I., Sweatman, H. and Williamson, D.H. 2008, Rapid increase in fish numbers follows creation of world's largest marine reserve network. Current Biology 18: 514-515.

Spatial Coverage

Cairns to Capricorn Bunkers

Temporal Coverage

Up to 2 years

Update Frequency

Annual and bi-annual 

Other Information

Supplemental data are available at

http://www.current-biology.com/cgi/content/full/18/12/R514/DC1