Abstract
<p>Indo-Pacific lionfishes (Pterois volitans and P. miles) are the first non-native marine fish species to become established in the western Atlantic and are now abundant along the eastern seaboard of the United States, the Caribbean Sea, and the Gulf of Mexico. To help resource managers control and mitigate the negative impacts of lionfish populations on coral reef ecosystems, the South Florida/Caribbean Network is monitoring invasive lionfish populations in Biscayne National Park (BISC) and Dry Tortugas National Park (DRTO) using Reef Visual Census (RVC) data. Utilizing RVC data from 2009-2012, this study spatially analyzed temporal changes in lionfish distributions throughout BISC, DRTO, and the Florida reef tract. Since 2010, there has been an overall increase in lionfish density, occurrence, and abundance. During this period, both mean and maximum observed lengths have also increased. Comparison of percent occurrence by depth and stratum in the Florida Keys region suggests a habitat preference for deep (>18m) low-relief forereefs. A similar comparison in the Dry Tortugas suggests habitat preferences for isolated and contiguous reefs with medium-high levels of relief. It is likely that, due to limited lionfish detectability and relatively few surveys in some locations, RVC data significantly underestimate lionfish population metrics and the extent of the species’ distribution within the sampling domain. However, our ability to identify and interpret trends in lionfish population changes will improve significantly in the future, as additional datasets become available.</p>