Contrasting patterns of vertical and horizontal space use of two exploited and sympatric coral reef fish

Understanding spatial distribution and temporal variation in movement patterns of closely related species is relevant for deciphering how resources are selected and whether interactions between species affect resource use patterns. The horizontal space use and vertical space use of two exploited reef fish, Plectropomus leopardus and P. laevis (all adults), were compared at mid-shelf Helix Reef and Lodestone Reef in the Great Barrier Reef over ~3 years using passive acoustic telemetry. Both species were detected throughout the 12-month duration of transmitters (mean detection period: ~270 days) and often made deep movements to ~40 m possibly related to reproductive behaviour (spawning). Differences in space use were apparent between species, with P. laevis consistently using greater area around reefs throughout the year. Overall, depth use patterns were similar between species; however, when daily detections were grouped in 2-h periods, P. laevis remained shallower and had greater variation in depth use compared to P. leopardus. Contrasting patterns of space use between these co-occurring species, in conjunction with known dietary dissimilarities, indicate distinct habitat use and resource preferences that are important for conservation and fisheries management.