Abstract
Background: South Africa hosts a large number of non-native freshwater fishes that were introduced for various industries. Many of these species are now listed under the National Environmental Management: Biodiversity Act (NEM:BA) Alien and Invasive Species (AIS) lists and regulations, though the practical options available to conservation agencies to effectively manage these fishes vary greatly among species and regions. Objectives methods: We assessed the history and status of national legislation pertaining to invasive freshwater fishes, and the practical implications of the legislation for managing different species with contrasting distributions, impacts and utilisation value. Results: The smallmouth bass, despite being a potential conflict-generating species, is fairly straightforward to manage based on current legislation. Two species of trout, which remain absent from the NEM:BA AIS lists because of ongoing consultation with stakeholders, continue to be managed in regions like the Western Cape province using existing provincial legislation. To maximise the limited capacity for management within conservation agencies, we proposed a decision-support tool that prioritises invasive fish populations that represent high environmental risk and low potential for conflict with stakeholders. Using three case studies, we demonstrated how the tool can be used to set management goals of ‘eradicate’, ‘manage against impacts and further spread’ and ‘continue to monitor population’ as the most pragmatic solutions given the state of an invasion, its socio-economic impact and the capacity of the responsible agency to act. Conclusion: By choosing a pragmatic management strategy, conservation agencies can maximise the effective deployment of limited resources, while minimising avoidable conflicts with stakeholders.
Highlights
Freshwater fishes form a key component of invasive alien fauna in many countries around the world, and several regions have fish communities with high proportions of non-native species (Leprieur et al 2008)
Many of the original goals for these introductions were successfully achieved, for instance, the creation of viable and economically important fisheries based on non-native species (e.g. Macchi et al 2008). These introductions have led to a number of negative ecological impacts (e.g. McDowell 2006; Weber & Brown 2009)
To illustrate the practicality of this decision-support tool, we demonstrate its hypothetical use with three realworld management scenarios from the present or recent past in South Africa
Summary
Freshwater fishes form a key component of invasive alien fauna in many countries around the world, and several regions have fish communities with high proportions of non-native species (Leprieur et al 2008). Many countries within these regions have attempted to balance the positive socio-economic benefits with the negative ecological impacts of invasive alien fishes in their management policies (Jackson et al 2004; Macchi et al 2008). This has included radical and, we suggest, potentially irresponsible proposed laws to ‘naturalise by decree’ invasive species, making them legally native to maximise their utilisation in aquaculture (Pelicice et al 2014). Many of these species are listed under the National Environmental Management: Biodiversity Act (NEM:BA) Alien and Invasive Species (A&IS) lists and regulations, though the practical options available to conservation agencies to effectively manage these fishes vary greatly among species and regions
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