Trophic Interactions and Habitat Quality of Invasive Lionfish in the Gulf of Mexico

Abstract

Lionfish (Pterois volitans and Pterois miles) are one of the most successful marine invaders of all time and pose a threat to native species that inhabit coral reefs, as well as overall reef health. Current management efforts in the invaded Atlantic region revolve around spearfishing to remove lionfish, often limited to 30 m depth. There is evidence that lionfish may seek refuge from fishing pressure in deeper habitat and replenish shallow sites, undermining this management strategy. To investigate the ecological implications of deep lionfish, size, reproductive capability, and diet were examined across a depth gradient for lionfish in the Florida Keys. It was found that size weakly increased with increasing depth and that shallow lionfish had higher reproductive potential. Sex ratios were female-biased in shallow sites. Lionfish are eating a range of teleosts and decapod species, including those of economic importance, and deeper lionfish are eating at a higher trophic level than shallow fish. These results were used to inform the parameters of a bioenergetic-based growth model for lionfish in the Gulf of Mexico. Prey energy density was modified to account for deeper (>30 m) lionfish’s increased consumption of teleost prey compared to shallow counterparts. Bottom temperatures at the locations of potential structured habitat were used to calculate the growth rate potential (GRP) of lionfish regionally and seasonally. There are regional differences in potential habitat that are not reflected in recorded lionfish sightings, and seasonal temperature changes do not limit lionfish growth in the GOM. A GRP model can be a useful tool to identify areas of lionfish growth and inform where management efforts can be focused for removals, particularly for lionfish at depth. This model could also be extended outside of the GOM to provide a management tool for the entirety of the lionfish’s invaded range.