Homing and spatial use of gag grouper,

Abstract

The homing ability and spatial use of gag grouper, Mycteroperca microlepis, in the northeastern Gulf of Mexico were studied between June 1997 and November 1998. Fourteen ultrasonically tagged gag were relocated to determine spatial area usage (0.01 to 26.68 Ha) before displacing gag to determine homing ability. Gag maintained a close association with a small core area within the spatial area they occupy. Gag expressed strong site fidelity, as demonstrated by homing to capture locations. Ultrasonically tagged gag displaced up to 8000 m (N=18) demonstrated their capacity to home from as far as 3000 m. Homing can occur quickly. For example, three gag homed after displacements of 600, 1000, and 2000 m within 65, 134, 122 minutes, respectively. Homing ability was tested at 2000, 3000, and 4000 m using externally tagged gag (N=90) and SCUBA to record homing success. Gag can home up to 3000 m, but as displacement distance increases the probability of homing decreases.