Precipitous Declines in Northern Gulf of Mexico Invasive Lionfish Populations Following the Emergence of an Ulcerative Skin Disease

Abstract

Invasive Indo-Pacific lionfish Pterois volitans/miles have become well-established in many western Atlantic marine habitats and regions. However, high densities and low genetic diversity could make their populations susceptible to disease. We examined changes in northern Gulf of Mexico (nGOM) lionfish populations following the emergence of an ulcerative skin disease in August 2017, when estimated disease prevalence was as high as 40%. Ulcerated female lionfish had 9% lower relative condition compared to non-ulcerated females. Changes in lionfish size composition indicated a potential recruitment failure in early summer 2018, when the proportion of new recruits declined by >80%. Remotely operated vehicle surveys during 2016–2018 indicated lionfish population density declined in 2018 by 75% on natural reefs. The strongest declines (77–79%) in lionfish density were on high-density (>25 lionfish per 100 m2) artificial reefs, which declined to similar levels as low-density (<15 lionfish per 100 m2) artificial reefs that had prior lionfish removals. Fisheries-dependent sampling indicated lionfish commercial spearfishing landings, commercial catch per unit effort (CPUE), and lionfish tournament CPUE also declined approximately 50% in 2018. Collectively, these results provide correlative evidence for density-dependent epizootic population control, have implications for managing lionfish and impacted native species, and improve our understanding of biological invasions.

Low Pufferfish and Lionfish Predation in Their Native and Invaded Ranges Suggests Human Control Mechanisms May Be Necessary to Control Their Mediterranean Abundances

“…However, in 2017, emergences of an ulcerative skin disease were first observed in the NGoM, with observations reported throughout the invaded Western Atlantic range (Harris et al, 2018). The NGoM lionfish populations exhibited a high prevalence of the disease and, within 18-months, their populations underwent dramatically (>50%) declines in recruitment, densities, and commercial landings (Harris et al, 2020a).…”

Testing the efficacy of lionfish traps in the northern Gulf of Mexico

“…This is higher than many fisheries where removal efficiency is <10% [63–65], but considerably lower than the >85% removal efficiency for spearfishing lionfish on nGOM artificial reefs [46]. Given spearfishing can reduce lionfish densities in areas frequented by divers [66–68] and spearfishing fisheries have caused severe depletion of other reef fishes [69–71], we expect spearfishing to remain the most efficient and cost-effective method for removing lionfish biomass at depths <40 m. Removal efficiencies and uncaptured lionfish will need to be considered when evaluating the potential community benefits offered by lionfish trapping as lionfish removals do not necessarily translate into ecological benefits [14,72,73] given lionfish predation [62,74], growth [53,75], and colonization [14,73,76] rates are controlled via density-dependent feedbacks. Ecosystem models may be appropriate for examining the potential community effects of a deepwater lionfish fishery [15,77].…”

A review of the diversity and impact of invasive non-native species in tropical marine ecosystems

“…However, the invasion may be entering a new phase in the western Atlantic. An ulcerative skin condition appears to be plaguing lionfish in their new range (Harris et al 2020) and their densities appear to be dropping in some locations (Benkwitt et al 2017).…”

“…In this example, this NNS may be more susceptible to parasites due to its unnaturally high population densities and low genetic diversityall common traits in the NNS discussed throughout this review. Ulcerative Skin Disease was only reported to affect lionfish in 2017 and may be why we are starting to see declines in this NNS across parts of its invaded range (Harris et al 2018(Harris et al , 2020. That said, there is also another negative impact this hostparasite interaction may yield, i.e.…”

“…that of parasite spillback. This is when native parasites cause mass infections in an NNS, and then subsequently the parasite transmits back to the native host population causing an increase in disease amongst native hosts (Harris et al 2020).…”