New research investigating if lionfish removals really matter. In short, this paper suggests it does. I can’t upload the paper now – check back later; but here is a nice summary. The authors’ summary after the jump.
Also, note in the authors’ short video above how hidden the lionfish is. As we have mentioned before, lionfish culling surely seems to be altering the behavior of remaining individuals.
Species invasions have a range of negative effects on recipient ecosystems, and many occur at a scale and magnitude that preclude complete eradication. When complete extirpation is unlikely with available management resources, an effective strategy may be to suppress populations of invaders below levels predicted to cause undesirable ecological change. We illustrate this approach by developing and testing targets for controlling Indo-Pacific lionfish on Western Atlantic coral reefs. We first developed a size-structured simulation model of predation by lionfish on native fish communities, which we used to predict threshold densities of lionfish beyond which native fish biomass should decline. We then tested our predictions by experimentally manipulating lionfish densities above or below reef-specific thresholds, and monitoring the consequences for native fish populations on 24 Bahamian patch reefs over 18 months. Reducing lionfish below predicted threshold densities effectively protected native fish community biomass from predation-induced declines. Reductions in density of 75- 95%, depending on the reef, were required to suppress lionfish below levels predicted to over-consume prey. On reefs where lionfish were kept below threshold densities, native prey fish biomass increased by 50-70%. Gains in small (<6cm) sizes of native fishes translated into lagged increases in larger size classes over time, with ecologically important grazers and economically important fisheries species increasing by 10-65% by the end of the experiment. Gains in native fish biomass were similar on reefs subjected to partial and full removal of lionfish, but partial removals took 30% less time to implement. Biomass of small native fishes declined by > 50% on all reefs with lionfish densities exceeding reef-specific thresholds. Large inter-reef variation in the biomass of prey fishes at the outset of the study, which influences the threshold density of lionfish, means that we could not identify a single rule-of-thumb for guiding control efforts. However, our model provides a method for setting reef-specific targets for population control using local monitoring data. Our work demonstrates that for ongoing invasions, suppressing invaders below densities that cause environmental harm can have a similar effect, in terms of protecting the native ecosystem on a local scale, to achieving complete eradication.