The Risk Analysis for Alien Taxa (RAAT) framework was developed to collate scientific information and interpret it in the context of South African regulations on biological invasions. Feedback from the past four years has shown RAAT to be a valuable tool for making evidence-based, transparent recommendations, but one that can be improved. We describe the changes made in creating RAAT v2.0. We note several issues that we suspect will apply to many similar processes, namely the need to i) clarify descriptions; ii) remove superfluous questions; and iii) add questions to fully justify recommendations. We also stress what RAAT v2.0 does not do—the framework does not summarise management best practices nor does it, or South Africa’s regulatory lists, provide sufficient information to prioritise management resources. We strongly recommend that explicit feedback mechanisms are set up to ensure that similar such frameworks can be improved over time.

Biological invasions, decision making, regulations, risk assessment

Risk analyses for alien taxa cover many aspects of biological invasions, such as the likelihood of introduction, establishment, spread, and impacts, management options as well as risk communication. Risk analysis frameworks are essential for the development of evidence informed regulation of alien species, with many new frameworks published in recent years (Sankaran et al. 2023). While some general standards for risk analyses have been identified (Roy et al. 2018), different regulatory frameworks often have slightly different requirements, which can explain the large variety of frameworks available (e.g., Verbrugge et al. 2010; Kumschick and Richardson 2013). For example, the European Union (EU) Regulation on Invasive Alien Species considers a selection of invasive species, all of which must be controlled in all member states (European Union 2014). In South Africa, however, the general approach is to list all invasive species that pose a risk of causing harm, with specific details of how to control taxa outlined in national management plans (Department of Environmental Affairs 2020), i.e., taxa are listed regardless of whether control programmes are likely to be feasible or effective. Regardless of the exact purpose of a risk analysis framework, it is important that the framework is evaluated, tested, and amended based on lessons learnt during its application. In particular, users can uncover inconsistencies, or highlight aspects that might be ambiguously worded; the science underpinning the frameworks advances; and the regulatory requirements might change (e.g., Weed Risk Assessment table in Kumschick and Richardson 2013; Kumschick et al. 2024).

In South Africa, the National Environmental Management: Biodiversity Act (NEMBA, Act 10 of 2004) Alien and Invasive Species Regulations (hereafter called the NEMBA A&IS Regulations; Department of Environmental Affairs 2020), list alien taxa that need to be managed. It separates taxa into different categories: Category 1a regulated taxa are considered nation-wide eradication targets; category 1b listed taxa require control; category 2 taxa can be used with permits under certain conditions and are 1b outside of permitted uses; category 3 taxa are exempt for certain uses but otherwise need control (i.e., somewhat similar to category 1b and 2, but no need for permits to keep existing individuals). There is also provision for a list of prohibited taxa, i.e., taxa which are not yet present and may not be imported into the country, although such a list was not included in the 2020 version of the regulations. For a detailed discussion of the NEMBA A&IS Regulations and the listing categories see Wilson and Kumschick (2024).

The Risk Analysis for Alien Taxa (RAAT) framework was developed to provide robust, scientifically based evidence to support the listing of alien taxa under the NEMBA A&IS Regulations. The framework provides a structured, transparent approach for the evaluation of the risks a taxon poses. The first version of RAAT (v1.0) was developed in 2017 in response to the need from government for a transparent framework to underpin the regulation of alien species. The framework underwent minor updates based on the initial experiences and was published as a preprint in 2018 (v1.1). In 2020, a trialled, tested, and revised version of RAAT was peer-reviewed and published in NeoBiota (Kumschick et al. 2020; see Suppl. material 1: table S2 for discussion on all the versions of RAAT to date). The framework has since been applied to various taxa as published in the scientific literature (Keet et al. 2020; Canavan et al. 2021; Matthys et al. 2022; Mbobo et al. 2022), and, as of 30 April 2024, has been applied to 123 of the 560 taxa regulated in South Africa and 17 taxa that are not currently regulated (Wilson and Kumschick 2024).

In many cases, assessors, reviewers, and the Alien Species Risk Analysis Review Panel [ASRARP, an independent scientific body which oversees the review process, see Wilson and Kumschick (2024) for details], broadly agreed both with the scoring of particular sections and with the final recommendations. Changes suggested during review were almost always agreed upon and the additional information provided a more solid basis on which recommendations were built. The main exception was that conflict taxa (i.e., taxa which cause negative impacts through invasions but have benefits to some sectors of society), could often not be confidently assigned to a regulatory category. Conflict taxa in South Africa include invasive freshwater fishes used for recreational angling that have caused the extirpation of native fish populations through predation, animals used as pets that can escape captivity and pose a threat to native species, and various ungulates introduced to game farms that can pose a threat to the genetic integrity of native taxa (see also Zengeya et al. 2017). Additional information was also deemed necessary to justify why certain exemptions were specified in the regulations or to justify conditions under which permits could or could not be issued. Furthermore, some information requested by the RAAT framework (e.g., on management best practice) was found not to affect the decision of whether and how to list a taxon. Certain sections were also not easily applied across taxonomic groups [e.g., propagule persistence can be critical to determine the feasibility of eradicating an invasive plant population (Panetta and Timmins 2004), but is less meaningful for many animals]. Therefore, after more than two years of applying and testing the framework, we re-evaluated the RAAT. This re-evaluation was based on the experience conducting assessments, reviewing assessments as part of the ASRARP, and teaching courses on how to apply RAAT (the later by S Kumschick).

Here we provide an overview of the main issues and gaps encountered with v1.2 of the RAAT, how they are addressed in v2.0, and flag general issues that might be useful for those who are revising similar such risk analysis frameworks.

We identified three broad issues: i) the need to clarify some descriptions in the guidelines; ii) some information requested was superfluous to classifying taxa or developing recommendations; and iii) additional information was needed to justify the recommendations. The following paragraphs present an overview of these issues, with details of the changes made between RAAT v1.2 and v2.0 (for full details see Suppl. material 1).

SK acknowledges the support of the Centre for Invasion Biology (CIB) at Stellenbosch University. We thank Katelyn Faulkner, Ashlyn Padayachee, and Nolwethu Jubase, as well as Pablo González-Moreno and Wolfgang Rabitsch for comments on an earlier version of the manuscript, and ASRARP members, people on the training courses and assessors for feedback on the RAAT.