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Risk Assessment Frameworks

The information on this website under the Phase 1 menu tab incorporates information compiled from the first phase of a four-phase project to produce a risk analysis to assess the potential to spread aquatic invasive species via seaplanes. At the conclusion of the project, recommendations will be made to enhance U.S. aquatic invasive species-seaplane prevention efforts. The DRAFT material posted in the Phase I section of the website represents a compilation of material from numerous sources, some of which may ultimately inform the risk analysis. The purpose of compiling this information was to better understand the seaplane pathway and identify key data gaps and information needed to inform the risk analysis. No analysis of this information has been conducted to date as content is refined and additional sources and content are added.

A risk assessment is a systematic approach to assess the scale and likelihood of arrival, establishment,  spread, and impact of nonnative species (Robertson et al. 2021, Venette et al. 2021). Risk assessments analyze, identify, and estimate the dimension, characteristics, and type of risk (Commission for Environmental Cooperation 2009). There are three categories of risk assessments—approaches that target lists of potential species, species-focused approaches, and pathway-focused approaches (Lonsdale 2011). Pathway-focused risk assessments estimate introduction potential and climate matching to predict establishment potential, however, single-pathway analyses may not result in a comprehensive assessment of all aspects of invasion risk (Davidson et al. 2017).


Risk assessments inform prediction, a process to forecast the likelihood and consequence of an invasion, and pathway analysis, a process to evaluate the means by which invasive species might be introduced (Venette et al. 2021). Prevention can be achieved through a combination of voluntary, policy, or regulatory approaches. Venette et al. (2021) emphasized pathway analyses and subsequent regulation of those pathways as frontline in the prevention of biological invasions (Hulme 2009) and cost-effective approaches (Leung et al. 2002, Keller et al. 2007, Essl et al. 2015; Tidbury et al. 2016).


Aquatic invasive species risk assessments can inform numerous aspects of AIS prevention and management efforts, including prioritizing resources for surveillance (Mahon et al. 2022), predicting establishment potential (Davidson et al. 2017), informing the development of effective legislation that lessens AIS introduction and spread (Horan et al. 2002, Simberloff et al. 2005, Keller and Perrings 2011, Mazzotti and Briggs-Gonzalez 2014), justifying initiatives that restrict trade, commerce, and consumer activities that contribute to AIS introduction and spread (Simberloff 2005, Davidson et al. 2017, Roy et al. 2017), and informing biosecurity strategies (Roy et al. 2019).


All risk assessments should incorporate (1) basic species description; (2) likelihood of invasion; (3) distribution, spread and impacts; (4) assessment of introduction pathways; (5) assessment of impacts on biodiversity and ecosystems; (6) assessment of impact on eco system services; (7) assessment of socioeconomic impacts; (8) consideration of status (threatened or protected) of species or habitat under threat; (9) assessment of effects of future climate change; (10) the ability to complete the assessment when information is lacking; (11) documents information sources; (12) provides a summary in a consistent and interpretable form; (13) includes uncertainty; and (14) includes quality assurance (Roy et al. 2018). Compiling information at a variety of scales and from numerous sources to crosswalk existing horizon scans with state and regional watch lists to develop a priority list of species for which detailed risk assessments can be conducted based on pathways of introduction has been used to identify introduction, establishment, environmental impact, and socio economic impact potential of numerous aquatic invasive species in the Tahoe Basin of California and Nevada (DeBruyckere and Draheim 2023).


The 18th Subsidiary Body on Scientific, Technical, and Technological Advice to the Convention on Biological Diversity (CBD 2014) documented six principal pathways of nonindigenous species introduction, including Transport Stowaway, which refers to the moving of live organisms attached to transporting vessels and associated equipment and media. This pathway most closely relates to the role seaplanes may play in AIS transport and introduction.


Estimating risk of aquatic invasive species introduction requires knowledge of three parameters—the number of invasive species individuals introduced, how frequently introductions occur, and an assessment of the environment in which the introduction occurs—to determine probability of establishment (Figure 2) (Stringham and Lockwood 2021). Failure to quantify any of these three parameters significantly reduces the ability to assess risk or take appropriate management actions to address risk and can result in under estimating establishment potential by as much as 50% (Stringham and Lockwood 2021).


This project builds upon previous studies on seaplanes in Alaska to evaluate the risk of the seaplane pathway as a vector for AIS and includes two components: a risk assessment, which forms the basis of risk analysis, and is supported by risk management and risk communication (Kumschick et al. 2020; Hill et al. 2020; Humschick et al. 2020), and identification of risk management actions.


The risk assessment is intended to:

  • Identify the travel patterns of seaplanes within the 48 contiguous states and Alaska, including the location and distance traveled between origin and final destinations, frequency of travel, and average time spent at each location.

  • Identify AIS that could potentially be moved by seaplane operations, including identifying high-risk areas of the plane (e.g., hull, float, wheel well) as well as operational or distribution practices and behaviors that may facilitate transport of AIS.

  • Assess the extent to which measures are taken by seaplane operators to prevent the transport of AIS.

  • Propose evidence-based recommendations for preventing the establishment and spread of AIS through seaplane operation and distribution, working with seaplane pilots to ensure recommendations are realistic and practical.

  • Propose evidence-based recommendations for preventing the spread of AIS through seaplane manufacturing to consider possible redesign opportunities if high-risk areas of the plane are identified.


This information will inform risk management actions that can be taken by seaplane operators, manufacturers, and others to reduce the spread of AIS.

Estimating risk

The Venn diagram illustrates the knowledge needed to adequately assess risk of introduction of aquatic invasive species. Source: Concept described in Stringham and Lockwood (2021).

Risk Assessment components
Graphic of seaplane
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