Abstract
The invasion of Indo-Pacific lionfish is one of the most pressing concerns in the context of coral reef conservation throughout the Caribbean. Invasive lionfish threaten Caribbean fish communities by feeding on a wide range of native prey species, some of which have high ecological and economic value. In Roatan (Honduras) a local non-governmental organisation (i.e. Roatan Marine Park) trains residents and tourists in the use of spears to remove invasive lionfish. Here, we assess the effectiveness of local removal efforts in reducing lionfish populations. We ask whether reefs subject to relatively frequent removals support more diverse and abundant native fish assemblages compared to sites were no removals take place. Lionfish biomass, as well as density and diversity of native prey species were quantified on reefs subject to regular and no removal efforts. Reefs subject to regular lionfish removals (two to three removals month−1) with a mean catch per unit effort of 2.76 ± 1.72 lionfish fisher−1 h−1 had 95% lower lionfish biomass compared to non-removal sites. Sites subject to lionfish removals supported 30% higher densities of native prey-sized fishes compared to sites subject to no removal efforts. We found no evidence that species richness and diversity of native fish communities differ between removal and non-removal sites. We conclude that opportunistic voluntary removals are an effective management intervention to reduce lionfish populations locally and might alleviate negative impacts of lionfish predation. We recommend that local management and the diving industry cooperate to cost-effectively extend the spatial scale at which removal regimes are currently sustained.
Highlights
Biological invasions are a serious threat to ecosystem biodiversity and function (Lowe et al, 2000)
Stakeholder interviews and spatial extent of the removal efforts Targeted lionfish removals were largely sustained by the recreational dive industry which is responsible for 78% of the monthly total catch in the marine reserve, whereby tourists contributed with 13% of the catch
While lionfish removal efforts are broadly popular in the Caribbean, the extent to which these are embedded in community activities and management programmes, as well as their effectiveness and expected benefits may vary widely among countries
Summary
Biological invasions are a serious threat to ecosystem biodiversity and function (Lowe et al, 2000). Invasion patterns and processes are well known in terrestrial ecosystems whereas marine invaders are far more common and occur in all marine. Invasive species in both marine and terrestrial ecosystems usually occupy low trophic levels (e.g. algae, invertebrates) (Byrnes, Reynolds & Stachowicz, 2007; Cote, Green & Hixon, 2013). The invasion of the Caribbean sea by lionfish native to the Indo Pacific is a rare example of predatory fish invading coral reefs at a rate and magnitude previously undocumented in any marine system (Cote, Green & Hixon, 2013). A decade later, lionfish were established throughout the Caribbean becoming one of the most pressing conservation concerns throughout the region (Gomez Lozano et al, 2013)
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