Session introduction: conservation of multi-species reef fish spawning aggregations

Most commercially important reef fish species form transient spawning aggregations at specific times and locations in order to reproduce. These aggregations are extremely vulnerable to overfishing. Spawning aggregations of the most well studied species, nassau grouper, have been heavily overfished, and in some cases, extirpated. Spawning stock surveys at nine aggregation sites in Belize during January 2001 revealed six nassau grouper aggregations as critically threatened, with less than 400 individuals, and the healthiest site had less than 6,000 fish, just a fraction of historical aggregations. Several other species were aggregated at and during the nassau grouper aggregations. In addition, a single promontory harbored 26 reef species spawning aggregations through various seasons suggesting that promontories used for spawning by one species, may be used by many species. Examples of multi-species spawning aggregations at reef promontories and channels can also be found in Mexico, Komodo, and Palau. It is possible that the oceanographic, bathymetric and physical oceanographic characteristics of these promontories and channels make them optimal locations for spawning for a variety of reef species. The time and location of two spawning aggregations was predicted using satellite imagery and a knowledge of the seasonality of spawning by species and verified in the field. These techniques might help reveal additional spawning sites throughout the region. Reef promontories, harboring multi-species spawning aggregations should figure more prominently in marine reserve designs.