While management strategies can be effective at achieving reef fisheries' conservation goals, a new study reveals how increased human pressure makes conservation of coral reef biodiversity truly difficult to achieve. Earth's coral reefs are not only home to some of the planet's richest collections of biodiversity, they also provide food and ecosystem services to millions of people worldwide. Yet, these fragile environments are highly susceptible to the impacts of climate change and increasing human pressure. As a result, many reefs across the globe are in steep states of decline. In order to sustain coral reef ecosystems and the livelihoods of the people who depend on them, there is a need for management tools capable of achieving multiple social and ecological goals related to ecosystem functioning and biodiversity, and to fishery health. However, little is known about how best to implement this type of ecosystem-based management approach, where multiple goals are simultaneously evaluated and perused. Joshua Cinner and colleagues compiled data from roughly 1,800 tropical reef sites worldwide to better understand the conditions under which reef ecosystems can simultaneously support three key ecological metrics representing reef health and use: reef fisheries, ecological function and biodiversity. Specifically, Cinner et al. evaluated each of these key traits by measuring fish biomass, parrotfish grazing activity and overall fish trait diversity, respectively. The findings suggest that when human use is low, all three traits can be maximized through high conservation levels. However, with increased human use and pressure, it becomes far more challenging to ensure biodiversity conservation - even at the highest levels of protection.