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Coral reef fisheries depend on reef fish biomass to support ecosystem functioning and sustainable fisheries. Here, we evaluated coral reefs across 4,000 km of the Indonesian archipelago to reveal a large gradient of biomass, from <100 kg/ha to >17,000 kg/ha. Trophic pyramids characterized by planktivore dominance emerged at high biomass,suggesting the importance of pelagic pathways for reef productivity. Total biomass and the biomass of most trophic groups were higher within gear restricted and no-take management, but the greatest biomass was found on unmanaged remote reefs. Within marine protected areas (MPAs), 41.6% and 43.6% of gear restricted and no-take zones, respectively, met a global biomass target of 500 kg/ha, compared with 71.8% of remote sites. To improve conservation outcomes for Indonesia's biodiverse and economically important coral reef fisheries, our results suggest to: (1) strengthen management within Indonesia's existing MPAs and (2) precautionarily manage remote reefs with high biomass. K E Y W O R D Sdata-poor fisheries, food webs, gear restrictions, marine protected areas, small-scale fisheries, South East Asia Conservation Letters. 2020;13:e12698.wileyonlinelibrary.com/journal/conl

Calls for coral reef restoration are increasing amidst continued declines, yet we know little about long-term outcomes and conditions that lead to successful coral recovery. Here, we report on one of the longest monitoring studies following 16 years of large-scale, "low-tech" experimental reef rehabilitation on rubble fields created by chronic blast fishing in Komodo National Park, Indonesia. After blast fishing had stopped, in the absence of rehabilitation, hard coral cover in rubble fields remained about 3% from 1999 to 2016, but on rehabilitation treatments, cover increased from 0% in 2002 to 44.5% (±21.9% SD) in 2016. Coral cover varied among sites and treatments (ranging from <5 to >80% in 2016) in patterns that may reflect current strength and turbidity. Our results demonstrate that low-tech substrate stabilization can facilitate natural coral recruitment and growth. We conclude that relatively low-cost methods can deliver sustained rehabilitation of hard coral cover and that long-term monitoring should be incorporated more widely in restoration activities to inform return on investment.

Marine reserves are a commonly applied conservation tool, but their size is often chosen based on considerations of socioeconomic rather than ecological impact. Here, we use a simple individual-based model together with the latest empirical information on home ranges, densities and schooling behaviour in 66 coral reef fishes to quantify the conservation effectiveness of various reserve sizes. We find that standard reserves with a diameter of 1-2 km can achieve partial protection (ࣙ50% of the maximum number of individuals) of 56% of all simulated species. Partial protection of the most important fishery species, and of species with diverse functional roles, required 2-10 km wide reserves. Full protection of nearly all simulated species required 100 km wide reserves. Linear regressions based on the mean home range and density, and even just the maximum length, of fish species approximated these results reliably, and can therefore be used to support locally effective decision making.