Characterization of Transient Multi-Species Reef Fish Spawning Aggregations at Gladden Spit, Belize

Gladden Spit, a salient reef promontory on the Belize Barrier Reef, is an important fishing ground for snappers and serves as a multi-species spawning aggregation site for several species of reef fish. Interviews with fishermen led to this study relating geomorphology and environmental conditions, especially currents, to transient fish aggregations and spawning. Based on multi-year observations, we describe direct evidence of spawning for 17 species of transient spawning reef fish from six families. Cubera snapper Lutjanus cyanopterus (Cuvier, 1828), mutton snapper Lutjanus analis (Cuvier, 1828), and dog snapper Lutjanus jocu (Bloch and Schneider, 1801) were most prominent in abundance, biomass, and egg production, although other large and commercially important species, including members of the grouper (Serranidae) and jack (Carangidae) families were also well represented. Spawning occurred throughout the year with species-specific patterns of spawning time (seasonality) and location (site fidelity). All spawning occurred above the shelf edge within a 6 ha area on the shelf just seaward of the reef promontory, in depths from 35 m to the surface. All spawning occurred between full moon and new moon, and all spawning took place near or after sunset with the exception of one species that spawned in the afternoon. Currents were faster and more variable at the spawning site compared to adjacent shelf edge areas. We hypothesize that steep relief and highly variable currents at gladden Spit are important factors for adults of many fish species selecting the promontory for aggregation and spawning.