Fig. 1: Field evidence for the influence of top-down control of outbreaks of crown-of-thorn starfish (CoTS).

In a study of 13 coral reefs of oceanic islands in Fiji, (A) shows the relationship between fishing pressure (as measured by people km^–1 reef) and density of mesopredatory (piscivorous and invertivorous) fishes and, (B) shows the relationship between fishing pressure and average density of CoTS. Islands where no starfish were recorded are shown as grey symbols. Solid line is a linear regression that does not include grey symbols. Plots redrawn from Dulvy et al.¹⁰ C shows the occurrence of outbreaks of CoTS on mid-shelf reefs (where most outbreaks occur) on the Great Barrier Reef from 1994–2004. Reefs are categorised by management zoning in the Great Barrier Reef Marine Park (GBRMP) as open to fishing (red) or no-take marine protected areas (teal). Dark shaded bars show reefs with outbreaks, light shaded bars show reef with no outbreaks. Over a decade, only 20% of no-take mid-shelf reefs suffered outbreaks whereas outbreaks occurred on 75% of mid-shelf reefs open to fishing. Plot redrawn from Sweatman¹². D Boxplots of model outputs showing effects of management zoning on likelihood of outbreaks of crown-of-thorns on 56 paired reefs, one open (red) and the other closed (green) to fishing spread across the Great Barrier Reef from 2006–2020. Plot redrawn from data in Kroon et al.¹¹.