Homing and site fidelity in the greasy grouper Epinephelus tauvina (Serranidae) within a marine protected area in coastal Kenya

Homing ability and site-fidelity in the greasy grouper Epinephelus tauvina (Serranidae) were studied at Malindi Marine Park (6.3 km2), coastal Kenya, from January to April 2002 using acoustic telemetry. Displacement experiments involving 12 groupers (mean size 57.9 cm) from multiple capture sites resulted in a 67% homing success. Upon release at displacement sites (0.5 to 2.6 km from the point of capture), most initial movements were small-scale and non-directional. Neither the tidal range nor time of day influenced the magnitude of these daily movements. Returns to the capture sites were sudden, occurring predominantly (88%) on spring tide dates. Fish displaced at the spring tide returned to capture sites faster (8.6 d) than those displaced at the neap tide (14.3 d). Time taken to return to capture sites ranged from 4 to 19 d (mean 9.6 d) and was not correlated with distance of displacement. However, time taken for the fish to home was negatively correlated with tidal range at displacement. Home ranges established after homing (0.07 to 0.73 km2) were stable and negatively correlated with fish size, suggesting an ontogenetic shift in home range development.