Movements of reef predators in a small, isolated Marine Protected Area with implications for resource management
Predators play a critical role in maintaining the balance of marine ecosystems and are an important component of Hawaii’s recreational and commercial fisheries. In light of the increasing pressures on these populations in recent decades across the main Hawaiian Islands, the study of predator movements in marine protected areas has become a research priority. To this aim, we used passive acoustic telemetry to investigate the spatial and temporal movement patterns of five apex predators: bluefin trevally (Caranx melampygus), giant trevally (Caranx ignobilis), green jobfish (Aprion virscens), whitetip reef sharks (Triaenodon obesus) and grey reef sharks (Carcharhinus amblyrhynchos) at the 31 ha Molokini Marine Life Conservation District (MLCD) off Maui, Hawaii. Our results indicate that the predator assemblage in the MLCD was dominated by teleost fishes during the day and sharks at night. Residency was variable across species, with bluefin trevally exhibiting the highest residency in the MLCD and green jobfish the lowest. Bluefin trevally showed displacement from tourist vessels during peak visitation hours. Long distance movements between the Molokini MLCD and the other islands of the Maui Nui Complex were common for grey reef sharks, giant trevally, and green jobfish. These results indicate that despite its small size, the Molokini MLCD provides a high level of protection to resident species such as bluefin trevally. While the more mobile species (giant trevally, grey reef sharks and green jobfish) are protected while resident at the MLCD but open to the fishery during these large scale movements away from the reserve.