Dynamics of Camouflage (Epinephelus Polyphekadion) and Brown Marbled Grouper (Epinephelus Fuscoguttatus) Spawning Aggregations at a Remote Reef Site, Seychelles

Aggregations of camouflage, Epinephelus polyphekadion (Bleeker, 1849), and brown marbled grouper, Epinephelus fuscoguttatus (Forsskål, 1775), were found to overlap spatially and temporally at a reef pass site located in the outer island group of the archipelagic Seychelles. Over three spawning seasons, we investigated the spatial and temporal dynamics of aggregations using a combination of underwater visual census (UVC) surveys and trends in reproductive parameters, notably gonadosomatic index. Interannual variation in aggregation formation was evident for both species, but was more variable in camouflage grouper. Aggregations lasted between 2-3 wks, with peak abundances attained a few days prior to the new moon, soon after which aggregations quickly dispersed. Spawning within aggregations was confirmed using direct (observations of hydrated oocytes) and indirect (gonadosomatic indices, behavior, color changes) signs. Spawning seasons were estimated at between 2 and 3-mo long, occurring between November and February, with interannual variation in onset and termination. Tagged camouflage grouper exhibited site fidelity on scales of weeks to months, and one individual returned to the aggregation the following year. The aggregations are known to fishers and are commercially exploited. Fisher knowledge was found to be a reliable source of information for locating aggregations.