Fish use of restored shellfish reefs extends beyond the reef edge

Global loss of shellfish reefs has necessitated widespread restoration efforts, with fish population enhancement a key motivator. Restoring reefs often involves creating multiple individual reef patches to maximize services within a given budget. How patch arrangement influences fish utilization is valuable information for optimizing restoration designs but remains largely unknown. We used remote underwater video stations to monitor fish on reef patch edges (0 m) and at distances of 2, 7, 12, and 500 m away. For 2, 7, and 12 m, we surveyed an inner zone that penetrates within the reef complex and an outer zone surrounding it. We detected 22 species across 66 camera deployments. Species richness was similar between zones and highest at the reef edge. Species assemblages were also similar between zones, with three distinct communities present: one at 0 m, a cluster including 2, 7, and 12 m, and another at 500 m. Most species, including bluespotted goatfish ( Upeneichthys vlamingii ), leatherjackets ( Monocanthidae spp.) and southern squid ( Sepioteuthis australis ) were more abundant on and alongside reefs than 500 m away. Habitat use, measured as the frequency of occurrence in footage, mirrored abundance patterns, suggesting more abundant species show stronger site fidelity. Individuals at the restored reefs utilize an area of at least 12 m around patches, providing some support to the status quo of creating multiple reef patches to form a network of restored habitat and the possible inclusion of unstructured areas around patches in assessments of restoration benefits for enhancing fish habitat.