The levelling-off and recent rapid decline in population density of the highly prolific invasive lionfish on the Saba Bank, Eastern Caribbean

Since its introduction in the Western Atlantic more than 30 years ago, the lionfish (Pterois volitans/miles complex) has spread throughout the Gulf of Mexico, the Caribbean and the Western Tropical Atlantic, with massive and unprecedented ecological impacts. This invasion is among the most studied marine fish invasions but very little is still really known about the population dynamics of the species and the factors ultimately governing its abundance. The species was first documented on the Saba Bank in 2010 and rapidly increased in abundance till the end of 2014. In this note we document its rise and subsequent decline in density and thereby describe the species’ third apparent local population boom-bust event for the Greater Caribbean. We also document gradual increases in the mean size of lionfish of the Eastern Caribbean Saba Bank that coincided with the increase and subsequent decline in abundance. Contrary to the previously documented epizootic disease outbreak associated with the population crash observed in the Gulf of Mexico we were unable to find any signs of the occurrence of epizootic disease. We suggest that the population decline on the Saba Bank might have been due to non-local causes. Boom-bust dynamics are often witnessed in biological invasions and have critical implications for both understanding and managing invasive species. While the underlying cause for the boom-bust event we document remains unknown, our work suggests that in the region, ecological feedback mechanisms are gradually developing that can help level-off deleterious population excesses of this invasive species.