This study confirms reports by fishermen of a large and predictable aggregation of whale sharks Rhincodon typus along the Belize Barrier Reef. Although whale sharks are rarely sighted at this location during most of the year, we counted as many as 25 whale sharks in a 50 m diameter area on 1 occasion and tagged 6 sharks during a 22 min period on another. The whale shark aggregation coincides seasonally and temporally with a multispecies reef-fish spawning aggregation at a reef promontory, Gladden Spit, at sunset, during the full and last-quarter moon periods of April and May each year. We report here, for the first time, that whale sharks feed on the freshly released spawn of cubera snappers Lutjanus cyanopterus and dog snappers L. jocu (Lutjanidae), and have documented the phenomenon with still and digital video photography of hundreds of feeding events. There is consensus locally that this remarkable interaction is in need of immediate protection from overfishing of snappers and unregulated tourism development. Our continued investigations are providing management recommendations for a new marine reserve at the site.

Marine ecosystem management has traditionally been divided between fisheries management and biodiversity conservation approaches, and the merging of these disparate agendas has proven difficult. Here, we offer a pathway that can unite fishers, scientists, resource managers and conservationists towards a single vision for some areas of the ocean where small investments in management can offer disproportionately large benefits to fisheries and biodiversity conservation. Specifically, we provide a series of evidenced‐based arguments that support an urgent need to recognize fish spawning aggregations (FSAs) as a focal point for fisheries management and conservation on a global scale, with a particular emphasis placed on the protection of multispecies FSA sites. We illustrate that these sites serve as productivity hotspots – small areas of the ocean that are dictated by the interactions between physical forces and geomorphology, attract multiple species to reproduce in large numbers and support food web dynamics, ecosystem health and robust fisheries. FSAs are comparable in vulnerability, importance and magnificence to breeding aggregations of seabirds, sea turtles and whales yet they receive insufficient attention and are declining worldwide. Numerous case‐studies confirm that protected aggregations do recover to benefit fisheries through increases in fish biomass, catch rates and larval recruitment at fished sites. The small size and spatio‐temporal predictability of FSAs allow monitoring, assessment and enforcement to be scaled down while benefits of protection scale up to entire populations. Fishers intuitively understand the linkages between protecting FSAs and healthy fisheries and thus tend to support their protection.

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Cubera snapper Lutjanus cyanopterus aggregated to spawn at Gladden Spit, a salient sub‐surface reef promontory seaward of the emergent reef and near the continental shelf edge of Belize. Their spawning aggregations typically formed 2 days before to 12 days after full moon from March to September 1998–2003 within a 45 000 m2 reef area. Peak abundance of 4000 to 10 000 individuals was observed between April and July each year, while actual spawning was most frequently observed in May. Spawning was observed consistently from 40 min before to 10 min after sunset within a confined area ≤1000 m2. Data suggested that cubera snapper consistently formed seasonal spawning aggregations in relation to location, photoperiod, water temperature and lunar cycle, and that spawning was cued by time of day but not tides. The cubera snapper aggregation site was included within the Gladden Spit Marine Reserve, a conditional no‐take fishing zone.