Reef relief and volume are predictors of Atlantic goliath grouper presence and abundance in the eastern Gulf of Mexico

Abstract

Atlantic goliath grouper, Epinephelus itajara (Lichtenstein, 1822), presence, abundance, and size distribution were assessed during monthly underwater visual surveys at natural and artificial reefs in the central eastern Gulf of Mexico (7–50 m depth). Atlantic goliath grouper were more likely to be present, and to occur in greater abundance, at artificial reefs. Abundance was positively related to vertical relief and structural volume, and the largest numbers of individuals were observed at high volume artificial reefs (e.g., shipwrecks). This was likely due to greater refuge availability provided by artificial reefs within the study region, where structurally comparable natural habitats are rare. Atlantic goliath grouper measured via underwater video ranged in size from 36 to 214 cm total length (TL; median = 121 cm). No relationship was observed between TL and site depth or reef type. Tagged individuals were documented to move distances ranging 10–203 km, but the majority of tag return data indicated high site fidelity. The strong site fidelity of goliath grouper combined with their continuous and predictable association with artificial reefs allows for relatively efficient monitoring of individuals within a given region; however, these traits also increase vulnerability to exploitation and underline the need for cautious management.