INTERACTIONS OF LARGE BENTHOPELAGIC MESOPREDATORS WITH SHELLFISH ENHANCEMENT ACTIVITIES IN FLORIDA COASTAL WATERS

Shellfish aquaculture “grow-out” sites for Northern Quahog (Mercenaria mercenaria) clams have substantially higher densities than the surrounding ambient environment and thus can attract local molluscivores to these areas. I used acoustic telemetry to examine potential interactions of two highly mobile ray species (cownose ray, whitespotted eagle ray) with two clam grow-out sites in the Indian River Lagoon near Sebastian, FL, where clammers have reported damaged grow-out gear. Visitation patterns of telemetered rays to these sites were compared to other reference sites in the region and modeled using local environmental data. While both species spent greater time elsewhere, I found many instances in which rays remained within range of clam grow-out sites for extended periods (>60 minutes). Mesocosm experiments with whitespotted eagle rays confirmed they were capable of interacting with and damaging clams housed within antipredator materials, although mortality was significantly reduced compared to controls and in particular by multi-layer netting.