Sea bottom geomorphology of multi-species spawning aggregation sites in Belize

Large, commercially important coral reef fishes such as Nassau grouper Epinephelus striatus are known to spawn at specific places and times in a so-called transient fish spawning aggregation (FSA). Traditional E. striatus spawning sites also serve as multi-species FSA sites. Many sites have been extirpated by overfishing or have shown dramatic declines. The objectives of this paper are to: (1) characterize the sea bottom geomorphology of all known transient FSA sites in Belize; (2) provide an evaluation of the multi-species aspects of known FSA sites; and (3) evaluate a prediction of 2 potential FSA sites based on the relationship between seafloor characteristics and fish aggregations. The reef structures surrounding FSA sites were defined in relation to their depth and proximity to shelf edges, deep water, reef channels, and reef promontory tips. All (n = 14) transient FSAs occurred at convex-shaped reef structures jutting out over steep walls into deep water. All FSA sites were located <100 m from shelf edges and < 200 m from reef promontory tips, and at a mean of 78 62 m from 100 m depth. Geomorphologically distinctive features at known FSAs allowed us to identify 2 new multi-species FSA sites exhibiting similar characteristics. All the primary FSA sites in Belize are reef promontories, but the reasons why fish aggregate at these sites remain unclear.