Setting the record straight on invasive lionfish control: Culling works

Abstract

Indo-Pacific lionfish have invaded large parts of the western Atlantic, Caribbean and Gulf of Mexico, and have already caused measurable declines in native Atlantic reef fauna. Culling efforts are occurring across the region, particularly on coral reefs, to reduce local lionfish abundances. Frequent culling has recently been shown to cause a shift towards more wary and reclusive behaviour by lionfish, which has prompted calls for halting culls. However, the effectiveness of culling per se is not in question. Culling successfully lowers lionfish numbers and has been shown to stabilise or even reverse declines in native prey fish. In fact, partial culling is often as effective as complete local eradication, yet requires significantly less time and effort. Abandoning culling altogether would therefore be seriously misguided and a hindrance to conservation. We offer suggestions for how to design removal programs that minimize behavioural changes and maximize culling success.

Peer Review #1 of "Spatial variation in allometric growth of invasive lionfish has management implications (v0.2)"

“…Determining the feasibility of such initiatives requires modeling the change in biomass in response to changes in fishing mortality (i.e., culling). A common way to model this is via length-structured population models, where fish lengths are converted to weight to calculate total biomass (Barbour et al, 2011;Côté et al, 2014;Andradi-Brown et al, 2017). The allometric length-weight relationship is thus an essential component of these models, but this relationship can vary across regions as a response to biotic and abiotic conditions (Johnson and Swenarton, 2016).…”

“…Outcomes of previous studies suggest lionfish are likely to exhibit spatial heterogeneity in the lengthweight relationship for both behavioral and biological reasons. Important life history characteristics such as growth or natural mortality rates are often spatially variable for fish that exhibit sedentary behavior (Gunderson et al, 2008;Hutchinson, 2008;Wilson et al, 2012;Guan et al, 2013), and in fact, high levels of site fidelity and small home ranges are two primary reasons why culling programs are effective in reducing local adult lionfish populations (Fishelson, 1997;Kochzius and Blohm, 2005;Jud and Layman, 2012;Côté et al, 2014). Genetic analysis of lionfish also identified two genetically distinct invasive subpopulations between the Western Atlantic and the Caribbean, suggesting the existence of spatially explicit biological differences between populations as well (Betancur-R et al, 2011).…”

“…Genetic analysis of lionfish also identified two genetically distinct invasive subpopulations between the Western Atlantic and the Caribbean, suggesting the existence of spatially explicit biological differences between populations as well (Betancur-R et al, 2011). Site-specific studies that calculate the length-weight relationship of lionfish report variable estimates, and these differences may be increasingly important when estimating the potential effectiveness of lionfish culling programs (Barbour et al, 2011;Morris et al, 2011;Côté et al, 2014;Johnston and Purkis, 2015). However, the influence of using ex situ parameters when estimating the length-weight relationship remains unexplored.…”

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“…culling). A common way to model this is via length-structured population models, where fish lengths are converted to weight to calculate total biomass (Barbour et al, 2011;Côté et al, 2014;Andradi-Brown et al, 2017). The allometric length-weight relationship is thus an essential component of these models, but this relationship can vary across regions as a response to biotic and abiotic conditions (Johnson and Swenarton, 2016).…”

“…Outcomes of previous studies suggest lionfish are likely to exhibit spatial heterogeneity in the lengthweight relationship, which we summarize in two main causes. First, culling programs are effective in reducing local adult populations largely because lionfish exhibit high levels of site fidelity and small home ranges (Fishelson, 1997;Kochzius and Blohm, 2005;Jud and Layman, 2012;Côté et al, 2014). It is know that fish with sedentary behavior are likely to exhibit high levels of spatial variation in important life history characteristics such as growth or natural mortality rates (Gunderson et al, 2008;Hutchinson, 2008;Wilson et al, 2012;Guan et al, 2013).…”