Tracking an invasion: how the distribution and abundance of Lionfish (Pterois spp.) has changed along the U.S. Atlantic coast

Central to invasive species management plans or strategies is monitoring of the population on an appropriate scale, including a characterization of some basic components of the invasion, such as changes in distribution and abundance over time. This is true of the invasive Lionfish (Pterois volitans and P. miles) in the Atlantic waters off the southeast coast of the United States, where they have become established, but minimal information regarding region-wide metrics of long-term abundance and distribution exists. By utilizing videos from 2011 to 2021 from a fishery-independent survey, regionwide distribution and abundance trends were characterized with generalized additive models, using spatial, temporal, environmental, microhabitat features, and water property variables to explore their effects on these patterns. The probability of occurrence and relative abundance of Lionfish in the study area increased initially until reaching a peak in 2015–2017 and then declined to the end of the study period (2021). Lionfish distribution and relative abundance followed similar patterns throughout the time series, but there was no extension north or south in the region, indicating abundance levels were driven by the density of Lionfish and not changes in distribution. The same variables were identified in both models, indicating preferred habitat use and/or detectability of Lionfish can be accounted for in continued monitoring efforts and provide information for future mitigation efforts.