As nonindigenous species are a major threat to global biodiversity, cost-effective management requires identification of areas at high risk of establishment. Here we predict suitable environments of 14 high-profile species of nonindigenous snakehead (Channidae) and Asian carp (Cyprinidae) species in North America based upon ecological niche modelling and compare the driving environmental variables for the two fish groups. Snakeheads distributions were correlated with thermal factors, whereas those of Asian carps were related mainly to precipitation. Predicted suitable ranges for these nonindigenous species can be divided into three main areas: Mexico and the southern United States (five species); Mexico and the United States up to ~35 °N (three species); and most of Mexico, continuous United States, and southern Canada (six species). For the province of Ontario, we combined the number and location of aquarium stores and live fish markets with predicted areas of suitable environments to identify areas at risk of introduction and establishment. We identified several watersheds draining into northwestern Lake Ontario as having the highest risk, highlighting the increased predictive value of this approach.

Over the last 200 years, the fish fauna of the Great Lakes has changed significantly as a result of declines in native species and the deliberate and inadvertent stocking of non-native fishes. These changes have resulted in the global extinction of three taxa and the extirpation of 18 species lowering the number of currently extant native species in the Great Lakes basin from 169 to 148 species. A further 82 species have declined to the point of endangerment in at least one jurisdiction in the basin. The causes of these declines are primarily habitat alterations, aquatic invasive species, and overexploitation. Some significant changes in the fish fauna of the Great Lakes basin have also been the result of the successful introduction and establishment of 35 non-native species. In addition, 34 non-native species have been found in the basin, but have not, or are not thought to have, established reproducing populations. These species have been introduced through a variety of pathways including commercial shipping, dispersal, live trade, recreational boating and angling, and stocking. Many of these species have substantially impacted the Great Lakes ecosystem directly through predation and competition or indirectly through trophic disruption and disease transmission. The relative importance of pathways as a source of new introductions has changed over time, and can be expected to continue to change as a result of evolving regulations and trade patterns. The fish fauna of the Great Lakes basin will continue to change as the result of continuing threats to native species and ongoing introductions of non-native species, and such change will undoubtedly be influenced by climate change and human population growth.

Understanding the biological and socio-economic risks associated with existing and potential aquatic invasive species is essential for an aquatic invasive species program to be successful. Effective programs are based on risk analyses, in which risk assessment informs risk management and both are communicated to resource managers and the public. Risk assessments provide valuable information that can be applied to many areas of an aquatic invasive species program. Based on biological and socio-economic risk assessments, appropriate risk management actions related to prevention, early detection and rapid response, and control can be undertaken. In particular, biological risk assessments inform both socio-economic risk assessment and subsequent preventative, monitoring, and control management actions. The uncertainty and knowledge gaps identified in risk assessments help identify and prioritize future research. Risk assessments are used to identify the riskiest aquatic invasive species and pathways and can be used to identify effective management, policy, and legislative actions to minimize risk. This, in turn, allows for the optimal allocation of limited resources to combat aquatic invasive species; therefore, risk assessment should be considered the cornerstone of a successful aquatic invasive species program. This article describes the risk analysis of aquatic invasive species, with emphasis on biological risk assessment and how they can be managed using marine and freshwater examples, with particular emphasis on the risk assessment of Bigheaded Carps in North America.

Effective engagement among scientists, government agency staff, and policymakers is necessary for solving fisheries challenges, but remains challenging for a variety of reasons. We present seven practices learned from a collaborative project focused on invasive species in the Great Lakes region (USA-CAN). These practices were based on a researcher-manager model composed of a research team, a management advisory board, and a bridging organization. We suggest this type of system functions well when (1) the management advisory board is provided compelling rationale for engagement; (2) the process uses key individuals as communicators; (3) the research team thoughtfully selects organizations and individuals involved; (4) the funding entity provides logistical support and allows for (5) a flexible structure that prioritizes management needs; (6) a bridging organization sustains communication between in-person meetings; and (7) the project team determines and enacts a project endpoint. We predict these approaches apply equally effectively to other challenges at the research-management-policy interface, including reductions of water pollution, transitions to renewable energy, increasing food security, and addressing climate change.

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