Testing for top-down control: can post-disturbance fisheries closures reverse algal dominance?

  • Published source details McClanahan T.R., Muthiga N.A. & Coleman R.A. (2011) Testing for top-down control: can post-disturbance fisheries closures reverse algal dominance?. Aquatic Ecology, 21, 658-675.


This study is summarised as evidence for the following.

Action Category

Cease or prohibit all types of fishing in a marine protected area

Action Link
Marine Fish Conservation
  1. Cease or prohibit all types of fishing in a marine protected area

    A replicated, site-comparison study in 1996–2009 at eight coral reef sites in the Caribbean Sea, off Belize (McClanahan et al. 2011) found that over a 15 year period following closure of an area of a marine reserve to all fishing, there was a higher number reef fish species and higher abundance of some species groups compared to nearby fished reefs in the reserve, and the effect varied with level in the food chain. The total number of species was higher at unfished reefs (19–27) than fished reefs (17–20) and increased with time. Seven of 17 fish family groups were more abundant (individuals observed/5 min) inside than outside the reserve, nine were similar, and one (Pomacentridae) was more abundant outside (see paper for individual data by group). Snapper abundance (Lutjanidae) showed the largest increase inside the reserve over time (13–72), whilst remaining constant outside (7). Average abundance of carnivorous fish was higher inside than outside the reserve, including: fish-eating fish (16 vs 4); fish that feed on large invertebrates (2 vs 1) and fish that feed on small invertebrates (159 vs 126). Abundance of herbivorous fish (284 vs 298) and sponge-eating fish (1 vs 1) was similar inside and outside the reserve. Fish were surveyed by underwater visual censuses at four reefs in the conservation zone (71 km2, legal protection in 1993, no fishing since 1995) and four nearby reefs in the general use zone (190 km2, regulated fishing activity) of Glover’s Reef Marine Reserve. Each reef site was sampled 8–10 times during May-November between 1996–2009. Divers haphazardly swam over each reef for a total of 35 minutes and recorded the number and species of fish from seven taxonomic groups during separate 5-minute intervals.

    (Summarised by: Leo Clarke)

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