With a voracious appetite for juvenile fish and invertebrates, invasive alien red lionfish (Pterois volitans) constitute one of the greatest threats to the Caribbean’s coral reefs. Although the eradication of lionfish is no longer considered possible, population suppression to site-specific densities can allow native fish populations to recover. Understanding the diet of lionfish in invaded areas is critical to understanding local impacts they pose to coral reef communities. This study explored the diet of lionfish in the northern end of the Belize Barrier Reef and tested whether biological variables (size, sex or reproductive stage) affect the diversity and/or abundance of prey species consumed. Between 2011 and 2014, 1023 lionfish were dissected and their gut contents analysed in the Bacalar Chico Marine Reserve. Gut contents analyses revealed that large sized lionfish consumed the highest abundance of prey (Mean (M)= 3.27 prey items) compared to small (M= 1.74 prey items) and medium (M= 3.15 prey items) lionfish, and that reproductive females consumed a higher abundance of prey (M= 3.66) compared to non-reproductive females of the same size (M= 2.85). As we found that medium and large lionfish are generalist predators and feed on a diverse assemblage of prey items, the effects of lionfish on the biomass of any one species may be reduced. This may enable individual prey species to have relatively stable abundances, although this hypothesis bears further testing. If management efforts are focused on improving a site-specific population of an individual prey species, such as an endemic or threatened fish, it is important to include removal efforts of small lionfish, particularly if they inhabit the same niche habitat. However, we recommend that existing lionfish focused cull dives continue using non-size discriminatory methods in order to account for site-specific, ecologically and commercially important prey items and to deter the likelihood of a successful invasion.
Key words: Pterois volitans, Caribbean, coral reef; invasive species, prey diversity