Prevalence and severity of sublethal injuries in crown‐of‐thorns starfish relative to marine reserves in the Great Barrier Reef

Spatial and temporal stochasticity in the abundance and population dynamics of crown‐of‐thorns starfish (COTS; Acanthaster spp.) highlight the critical need for improved knowledge of demographic variability within and among populations. This study compared the prevalence (proportion of individuals) and severity (extent of damage) of injuries in adult COTS between contrasting fisheries management zones in Australia's Great Barrier Reef, explicitly testing whether injuries are more prevalent or severe on reefs where fishing is not permitted. Prevalence of sublethal injuries was significantly higher for COTS collected from reefs within Marine National Park Zones, where fishing is effectively prohibited, versus Conservation Park Zones or Habitat Protection Zones, where fishing is permitted, but regulated. This finding is consistent with the notion that predation rates on COTS are higher within reef habitats where fishing is prohibited, presumably due to the bigger size or higher abundance of predatory fishes. Severity was predominantly low among the injured starfish and there was no significant difference between management zones. Nevertheless, there was a higher frequency of individuals with between one and three injured arms in no‐take reefs compared to those from reefs that were open to fishing. Prevalence and severity of sublethal injuries was higher in medium‐sized COTS (11–30 cm diameter) compared to larger COTS (>30 cm diameter). This study adds to existing evidence that established networks of marine reserves can have benefits beyond conservation and fisheries management, including potential reductions in the likelihood of devastating population irruptions of COTS and mitigation of further coral loss.