Conservation benefits of no-take marine reserves outweigh modest benefits of partially protected areas for targeted coral reef fishes

Inshore coral reefs support unique ecosystems that are subject to a variety of threats and disturbances. Marine protected areas are powerful conservation tools and often include zones which vary in the level of fishing restriction, including fully protected (no-take) zones, partially protected zones (limited fishing), and less protected “open” fishing zones. Here, we compare outcomes from fully protected, partially protected, and “open” fishing zones on inshore fringing reefs of the Great Barrier Reef with a history of cyclone-induced habitat disturbance. Biomass of target and non-target fish groups, along with the coral cover and structural complexity of benthic habitats, was compared among zones. There was a strong positive effect of full protection from fishing on targeted fish biomass, and a comparatively modest effect of partial protection, even in areas where spearfishing was prohibited. Fully protected zones supported more than three times the biomass of highly targeted coral trout (Plectropomus spp.) compared to open fishing zones, and more than twice the biomass observed in partially protected zones. Similar outcomes occurred for primary targets collectively; conversely, there were no zoning-related differences for non-target fishes. Structural complexity was a consistent positive driver of fish biomass for all fish groups and among all zones. Notably high target fish biomass occurred at NTMR sites with the highest structural complexity, highlighting the importance of both habitat and protection in supporting population hotspots for targeted reef fishes.