Abstract

Bioinvasions have impacted Western Atlantic and Caribbean coral reef ecosystems, reducing their resilience and capacity to cope with other stressors. Pterois miles and P. volitans, originally from the Indo-Pacific and collectively known as lionfish, have now spread throughout the Western Atlantic, and pose a significant ecological threat to important native fishes and coral reef ecosystems. In 2000, Bermuda was the first jurisdiction outside of the United States to document non-native lionfish and, although they were initially uncommon, a lionfish culling program was established in 2008, and extensive surveys of lionfish densities and distribution across the Bermuda platform were carried out in 2013-14. Here we reassess the status and impact of the invasive population by repeating surveys of lionfish density, prey fish density, and prey fish biomass at five of the previously surveyed sites, across four depth zones: 10 m, 20 m, 30 m and 60 m, with a primary focus on the northern reef tract where initial lionfish densities were low and there has been little culling effort. Between 2014 and 2019, significant increases in lionfish density were found at sites along the northern reef tract at depths of 30 m and 60 m. Sites along the southern reef tract at 60 m depth with historically high lionfish densities maintained significantly greater lionfish densities than those on the northern reef tract. Prey fish diversity and biomass increased significantly at nearly all sites and depths. Notably, the XL site at 60 m experienced a significant reduction in lionfish density from 2014 to 2019, which is attributed to regular culling at that site. This reduction in lionfish density at XL coincided with a significant increase in fish biomass, highlighting the importance of active management to control lionfish populations.

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