Lionfish (Pterois volitans) Show Social Attraction to Conspecifics When Selecting Shelters

Group formation in animals can arise from two primary mechanisms: individuals aggregating over resources, or individuals socially benefiting from interacting with conspecifics. Distinguishing between these mechanisms allows us to infer the drivers of group formation, which is of considerable importance for informing management strategies of invasive species. Lionfish (Pterois volitans) are a teleost predator native to the Indo-Pacific but invasive in the Western Atlantic Ocean. Lionfish are often observed sheltering in refuges on their own or in groups, with previous research suggesting these groups form due to attraction towards preferred habitats rather than having a social function. Here, we find that lionfish were more likely to shelter with a conspecific rather than choosing to shelter alone. Lionfish were also more likely to shelter with larger conspecifics. Our findings demonstrate that lionfish are socially attracted to one another, which has implications for the control and management strategies of this invasive species.