Cubera snapper ( <i>Lutjanus cyanopterus</i> ) aggregation at Riley’s Hump, Tortugas South Conservation Area: indirect evidence for multispecies spawning aggregation recovery

Studying previously-fished multispecies 19 aggregation sites provides insight on how to manage them to ensure their continued reproductive success. Riley’s Hump is a historically overexploited multispecies aggregation site situated in the no-take Tortugas South Conservation Area, Florida Keys National Marine Sanctuary. This paper summarizes opportunistic observations of a cubera snapper ( Lutjanus cyanopterus ) aggregation collected from 2011 to 2020. By utilizing a variety of methods, collaborative multi-agency partnerships, and repeated visits to the aggregation site, we gathered indirect (echosounder) and direct (divers, ROV) evidence of significant biomass that persists across multiple months and years, from spring through fall, at the cubera snapper aggregation site. The persistent biomass present at Riley’s Hump during known cubera spawning months, color morphs associated with reproduction, and female morphs with visibly distended abdomens, suggests that this location is currently a significant and likely spawning aggregation site for this species, although direct confirmation of spawning remains to be obtained. In addition to cubera snapper, we confirmed the regular presence of multiple species of apex predators (e.g., Carangidae, Carcharhinidae, Serranidae). These observations provide further indirect evidence that the current no-take management designation of Riley’s Hump has been successful at maintaining a healthy ecosystem, characterized by snapper, grouper, and other species undertaking critical spawning activities, and higher trophic level species associated with this location and the activities and habitats that occur there. The multispecies spawning aggregations and deep reef habitats of Riley’s Hump can serve as a conservation “bright spot” for fish populations in the greater Florida region.