Calibration of FISK, an Invasiveness Screening Tool for Nonnative Freshwater Fishes

Abstract

Adapted from the weed risk assessment (WRA) of Pheloung, Williams, and Halloy, the fish invasiveness scoring kit (FISK) was proposed as a screening tool for freshwater fishes. This article describes improvements to FISK, in particular the incorporation of confidence (certainty/uncertainty) ranking of the assessors' responses, and reports on the calibration of the score system, specifically: determination of most appropriate score thresholds for classifying nonnative species into low-, medium-, and high-risk categories, assessment of the patterns of assessors' confidences in their responses in the FISK assessments. Using receiver operating characteristic (ROC) curves, FISK was demonstrated to distinguish accurately (and with statistical confidence) between potentially invasive and noninvasive species of nonnative fishes, with the statistically appropriate threshold score for high-risk species scores being >/=19. Within the group of species classed as high risk using this new threshold, a "higher risk" category could be visually identified, at present consisting of two species (topmouth gudgeon Pseudorasbora parva and gibel carp Carassius gibelio). FISK represents a useful and viable tool to aid decision- and policymakers in assessing and classifying freshwater fishes according to their potential invasiveness.

Colonisation of the Rhine basin by non-native gobiids: an update of the situation in France

“…using the calibrated version of the FISK (v2.03), which is freely available for download (Lawson et al, 2012). The critical thresholds for categorising fish species as low, medium or high risk of being invasive have been calibrated by Copp et al (2009), whereby scores <1 indicate low risk, scores of 1 to 18.9 indicate medium risk, and scores of 19 (to a maximum of 54) indicate high risk.…”

“…Following the same procedure, the upstream and downstream rates of range expansion along the Rhine River were also calculated. To assess the invasiveness potential of the Western tubenose goby, the round goby and the bighead goby, a pre-introduction screening tool, the Fish Invasiveness Screening Kit (FISK) (Copp et al, 2009) was used. It is composed of 49 questions in eight categories: (1) domestication, (2) climate and distribution, (3) invasive elsewhere, (4) undesirable traits, (5) guild, (6) reproduction, (7) dispersal mechanisms, and (8) persistence attributes.…”

Restoring River Connectivity: Prioritizing Passage Improvements for Diadromous Fishes and Lampreys

“…Similar methods are also widely used in the risk assessment of non-native species (e.g. Copp et al 2009;Tricarico et al 2010). The matrix developed here is rapid to use, requires only limited data, and is sufficiently flexible to be applied to a range of scenarios.…”

“…Indeed, the greatest sources of between-assessor differences in B were generally the estimates of F and P. It may also be possible to incorporate confidence rankings for estimates based upon expert judgement, as is being developed for risk assessment of non-native species (e.g. Copp et al 2009;Tricarico et al 2010).…”

Distribution of non-native brook trout (Salvelinus fontinalis) across Norwegian waterbodies – is it an invasive species?

“…For the majority of non-native species, no quantitative information is available regarding the consequences of such introductions (Simberloff et al 2013). Brook trout is classified as a medium-risk species among nonnative freshwater fish (Copp et al 2009;Britton et al 2010). Our article describes the distribution of brook trout in Norwegian water bodies.…”