Diel habitat-use patterns of commercially important fishes in a marine protected area in the Philippines

Abstract

The diel habitat-use patterns of commercially important fishes in a small marine protected area (MPA) (0.31 km2) containing coral reef and seagrass habitats were examined by passive acoustic telemetry during 2011 and 2012. The occurrence patterns of the target fishes both inside and outside the MPA were also observed. Thirty individuals from 6 species (20.2 to 41.4 cm fork length) were caught, acoustically tagged and released inside the MPA, and 4 to 210 d of tracking data were then obtained from 28 detected fishes. Lutjanus monostigma, Lethrinus atkinsoni, and Lethrinus obsoletus were found to mostly inhabit the coral reef. The remaining 3 species (Lutjanus argentimaculatus, Lethrinus harak, and Siganus guttatus) utilized both coral and seagrass habitats but showed different patterns: Lutjanus argentimaculatus visited seagrass only at night; Lethrinus harak occurred in the coral reef more at night than in the day, showing the opposite pattern in seagrass; and S. guttatus exhibited the converse pattern to L. harak. More than one-third of the tracked individuals moved inside and outside the MPA more than once per day on average during the tracking period. However, 95.4% of detections were recorded by acoustic receivers deployed inside the MPA. Underwater visual surveys revealed that the densities of some target fishes were significantly higher inside than outside the MPA. These findings suggest that the MPA protects the core of fish home ranges.