Abundance estimates of the Indo-Pacific lionfish Pterois volitans/miles complex in the Western North Atlantic

Less than a decade after being observed off Florida, the invasive Indo-Pacific lionfish is now widely distributed off the southeast coast of the United States. As a step towards measuring invasion impacts to native communities, we examine the magnitude and extent of this invasion by first, compiling reports of lionfish to provide range information and second, estimate lionfish abundance from two separate studies. We also estimate native grouper (epinepheline serranids) abundance to better assess and compare lionfish abundances. In the first study we conducted SCUBA diver visual transect surveys at 17 different locations off the North Carolina coast in water depths of 35 - 50 m. In the second study, we conducted 27 Remote Operated Vehicle (ROV) transect surveys at five locations from Florida to North Carolina in water depths of 50 - 100 m. In both studies, lionfish were found to be second in abundance only to scamp (Mycteroperca phenax). Lionfish were found in higher abundance in the shallower North Carolina SCUBA surveys ((x) over bar 21: 2 ha(-1)) than in the deep water ROV surveys ((x) over bar 5: 2 ha(-1)). Lionfish reports continue to expand most recently into the Bahamas, raising the specter of further spread into the Caribbean and Gulf of Mexico. The potential impacts of lionfish to native communities are likely to be through direct predation, competition and overcrowding. The high number of lionfish present in the ecosystem increases the potential for cascading impacts throughout the food chain. Within the southeast region the combined effects of climate change, overfishing and invasive species may have irreversible consequences to native communities in this region.