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Ingeman KE, Albins MA, Benkwitt CE, Green SJ, Kindinger TL, Tuttle LJ, Hixon MA.2017. Resolving differences in observed impacts of invasive lionfish and clarifying advice to managers. PeerJ Preprints5:e3455v1https://doi.org/10.7287/peerj.preprints.3455v1
Hackerott et al. (2017) report that Indo-Pacific lionfish “had no apparent effect on native prey communities” (p. 9) on continuous reef-sites of the Belizean Barrier Reef (BBR). Based on a lack of observational evidence, they challenge existing evidence for the effects of predation by lionfish on native prey community structure and assert that previous experimentally measured effects are inflated by “unnaturally high lionfish densities” (p. 10). Managers may mistakenly interpret these conclusions as evidence that invasive lionfish are of little concern and that active management of lionfish should not be a conservation priority. We find the arguments presented in Hackerott et al. (2017) unconvincing and potentially misleading. Here, we seek to evaluate their conclusions in the context of the body of work on the lionfish invasion, and to clarify advice to marine resource managers in the invaded range. Specifically, we argue that (1) the low lionfish densities observed in Hackerott et al. (2017) are not predicted to cause observable lionfish effects—so the results offer no countervailing evidence; (2) the study design is ill-suited to identify lionfish-induced changes in prey abundance, were they to occur; (3) the analytical methods employed (correlation between lionfish and prey densities) do not represent a BACI design nor offer a reliable test of predatory effects; and (4) the authors minimize potentially important regional management activities that could affect lionfish population densities and mischaracterize the body of lionfish research that has come before. Scientists should rigorously challenge popular scientific narratives.However, the foundation of such challenges must be carefully designed experiments, sound methodology, and conservative interpretation of one’s findings.