Coping with the lionfish invasion: Evidence that naïve, native predators can learn to help

Invasive species often exacerbate global and local stresses on ecosystems, with animal invaders commonly experiencing a release from enemies, including predators. Release from predation helps explain the lionfish (Pterois volitans/miles) invasion of the western Atlantic, Caribbean and Gulf of Mexico, although the extent of biological control exerted by native predators is a topic of debate centered on the interpretation of spatial distributions of lionfish and those predators. In many places, control of lionfish numbers relies on people acting as predators via organized culls. In some cases, the resulting dead or injured lionfish are eaten by sharks and groupers, which may condition these naïve, native predators. This study complements existing field surveys by assessing the potential for predation on invasive lionfish at Little Cayman Island, BWI with tethering experiments. We tethered 132 live lionfish (52-220 mm total length) in three different habitats: seagrass beds, rarely culled reefs, and intensely culled reefs. Binary logistic regression indicated that, across all habitats and the size range tested, the potential for predation increased slightly (1.02 ×) but significantly with 1 mm increases in total length. In addition, lionfish tethered on intensely culled reefs were approximately 30 × and 14 × more likely to be taken by piscivores than fish tethered in seagrass or on rarely culled reefs. Overall, results suggested that native predators were capable of consuming healthy, tethered lionfish off Little Cayman Island and the naïveté of native predators was overcome by conditioning. Of course, conditioning designed to increase predation on lionfish, augment culling, and help control the invasion must be implemented without endangering people.