Movement patterns of reef predators in a small isolated marine protected area with implications for resource management

TLDR: The results indicate that despite its small size, the Molokini MLCD provides a high level of protection to resident species such as bluefin trevally, but is less effective at protecting more mobile predators such as green jobfish, gray reef sharks and giant trevals.

Abstract: Reef 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 response to the increasing anthropogenic demands on these populations 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 reef predator species: bluefin trevally (Caranx melampygus), giant trevally (Caranx ignobilis), green jobfish (Aprion virescens), whitetip reef sharks (Triaenodon obesus) and gray reef sharks (Carcharhinus amblyrhynchos) at the 31 ha Molokini Marine Life Conservation District (MLCD) off Maui, Hawaii (Lat: 20°37′56.70″N, Lon: 156°29′44.52″W) from November 13, 2013 to August 28, 2015. 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, green jobfish the lowest, and long-distance movements between the Molokini MLCD and the other islands of the Maui Nui Complex were common for gray reef sharks and giant trevally. These results indicate that despite its small size, the Molokini MLCD provides a high level of protection to resident species such as bluefin trevally. However, this MLCD is less effective at protecting more mobile predators such as green jobfish, gray reef sharks and giant trevally.