Abundance patterns of reef sharks and predatory fishes on differently zoned reefs in the offshore Townsville region final report to the Great Barrier Reef Marine Park Authority

Abstract

Sharks were counted in six 500 x 20 m transects on the slope of each reef during late March 2008. Densities of whitetip reef sharks (Triaenodon obesus) were twice as high on green reefs as on blue reefs but were twice as high on pink reefs as on green reefs. Similarly, grey reef sharks (Carcharhinus amblyrhynchos) were four times as abundant on green reefs as on blue reefs, but twice as abundant on pink reefs as on green reefs. We also recorded the abundance of large teleost reef fishes during all counts. There were similar patterns in the density of the common coral trout (Plectropomus leopardus), with 1.5 times as many coral trout on green reefs as on blue reefs but 2.5 times as many on pink reefs compared with green reefs.