Abstract

Invasive lionfish (Pterois miles and P. volitans) have spread rapidly throughout the western Atlantic, and are now es-tablished from North Carolina to Venezuela. Generalist, opportunistic predators with a broad diet and no natural predators themselves, lionfish can have substantial impacts upon native fish communities wherever they are found. In 2000, Bermuda was the first location outside the United States to detect invasive lionfish. To better understand their potential impact and provide a baseline against which to judge population growth, underwater visual surveys were conducted at multiple depths around the Bermuda platform to map the distribution of lionfish and look for patterns in abundance. Captured lionfish pro-vided information on biomass and size-frequency distributions with depth. Lionfish sightings and captures reported by the public, fishermen and researchers added further insights into distribution patterns. Our surveys show that lionfish densities are greatest at mesophotic depths (>30m) around Bermuda, particularly off the south shore of the island where the seabed slopes steeply and provides deep and shallow habitats in close proximity. However, lionfish have been reported all across the shallow platform from a variety of natural and artificial habitats, with some indications that greater numbers may be present in shallower waters during the winter. Interestingly, greater proportions of both the smallest and largest lionfish size classes are found in shallow waters. At present, lionfish are found at lower densities around Bermuda than in other locations across the invaded range, suggesting that the local population is expanding at a slower rate than observed elsewhere.

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