Marine protected areas (MPAs) are important conservation tools, however, efficacy can, in part, be a function of their size in relation to the home range of the target species. The eastern blue groper, Achoerodus viridis, is a long-lived, protogynous hermaphrodite, and an 'iconic' marine species in eastern Australia, with several MPAs having been established specifically for their protection. Site fidelity, habitat use, and home range size were assessed for 29 adult eastern blue gropers monitored for up to 374days using passive acoustic telemetry within and around a small marine reserve. The fish exhibited long residency times and no movement was recorded between adjacent reefs, suggesting sand acts as a natural barrier to movement. Core ranges were calculated using 50% kernel utilization distributions (KUD) and estimated between 0.005 and 0.092km2. Males had larger core ranges than females or fish of indeterminate sex. There was no statistical difference between the breeding/non-breeding seasons. Home ranges were calculated using 95% KUD and ranged between 0.03 and 0.54km2. Home range size was largest for males and significantly larger for all sexes in the breeding season. Fish tagged in the 'no-take' area of the MPA had smaller home ranges than fish tagged in the area where fishing is permitted. This study indicates that even relatively small MPAs can provide effective protection for adult eastern blue groper, supporting the proposition that large reef dwellers with long residency times can be used as flagship species to gain public support for the designation of MPAs.