No-take marine reserves are known to increase fish populations within their boundaries, but their impact on surrounding fisheries has been less clear. This study combines decades of reef monitoring across 133 reefs, larval dispersal models, and commercial catch data, to evaluate how the Great Barrier Reef’s reserve network affects the wider reef system, including fisheries.
Although they cover just 30% of reef habitat, Great Barrier Reef marine reserves support about half of the total coral grouper (Plectropomus spp.) biomass, the region’s most important line fishery. Individual fish in reserves are on average 3 cm larger and more fecund, producing 96,100 eggs per batch versus 69,800 in fished areas. As a result, reserves contribute over half (55%) of total coral grouper egg production on the Great Barrier Reef.
Biophysical models showed that reserves are also responsible for about half (50%) of larval settlement across the reef system. Larval dispersal is complex and shaped by factors like reserve size, spacing, fish densities, and ocean currents. Still, the influence of reserves is widespread: 95% of reefs receive at least 30% of their larvae from protected areas, and more than half of the Great Barrier Reef’s reefs receive over 50% of their larvae from protected areas.
Although these reserves were designed primarily to conserve biodiversity, not fishery management, their benefits extend to fisheries. More and larger fish inside reserves lead to higher egg production, which in turn replenishes populations on both protected and fished reefs. The study estimates that 47% of the coral grouper caught by the commercial fishery were born within the Great Barrier Reef’s network of marine reserves.
These findings underscore that marine reserves are a critical component of the Great Barrier Reef ‘s ecosystem-based management strategy, helping to sustain both biodiversity and long-term fishery yields.
Implications for managers
- No-take reserves can be a powerful tool for both protecting biodiversity on reefs and sustaining productive, long-term fisheries.
- The effectiveness of marine reserves depends on factors like size, spacing, and connectivity. Reserve networks should be designed to enhance larval dispersal across reef systems.
Author: Bode, M. S. Choukroun, M.J. Emslie, H.B. Harrison, J.M. Leis, L.B. Mason, M. Srinivasan, D.H. Williamson, G.P. Jones
Year: 2025
Sci. Adv. 11(6):eadt0216. doi: 10.1126/sciadv.adt0216
