Development of a Quantitative Risk Assessment Tool to Predict Invasiveness of Non-native Freshwater Fishes in Everglades National Park

Science Center Objects

The introduction of non-native fishes is a problem across the United States, particularly in Florida. USGS scientists are developing a decision support tool to help natural resourece managers prioritize which species to focus prevention, detection, rapid response, and control efforts. 

Blue Tilapia (Oreochromis aureus)

Blue Tilapia (Oreochromis aureus)

(Credit: Noel Burkhead, USGS. Public domain.)

The Science Issue and Relevance: The introduction of non-native fishes is a problem across the United States, particularly in Florida, where over 100 species of fishes have been introduced into freshwater ecosystems (USGS-NAS 2019; nas.er.usgs.gov). Non-native fishes can cause a variety of detrimental effects on the ecosystem in which they are introduced, including competition with and predation on native species, spreading of disease, and modification of habitats. National parks are legally mandated to conserve the wildlife within their boundaries, and actively work to limit the spread of non-native species.

We propose the development of a decision support tool that will let natural resource managers prioritize species on which to focus prevention, detection, rapid-response, and control efforts. Additionally, the risk-assessment tool can be used to predict which fishes currently in the aquarium trade or aquaculture industry but not yet introduced into Florida’s waters may present the greatest threat for invasion and establishment. 

Map of Everglades National Park

Map of Everglades National Park

(Public domain.)

 

Methodology for Addressing the Issue: To develop this tool, we will collect, collate, and analyze existing biological and ecological data for a suite of non-native freshwater fishes. Data on non-native fish species that have already invaded Everglades National Park will be used as model training. Further, we will compare biological and ecological traits of species that have successfully invaded the Everglades with those that have not and will then assess the risk for invasion by fishes that are in nearby Florida waterways. We will also assess the risk of a suite of non-native fishes that have not yet invaded Florida but may do so because of their prevalence in the aquarium industry or presence in adjacent state waters. Our statistical analysis will be similar to that used by Kolar and Lodge (2002). 

One important improvement is that our analysis will be based on Multivariate Logistic regression.  This will provide a similar output to the Linear Discriminant Analysis used by Kolar and Lodge, but with the added flexibility of being able to use non-normal predictor variables, thus increasing its flexibility.  We will be able to assign the most likely outcome (succeed/fail), but we will also be able to assign uncertainty to each prediction, and through the modeling process, identify the predictor variable(s) that contribute most to the uncertainty.  From this analysis, we will identify which predictor variables are more important in predicting invasion success, which variables are not useful, and which need further data to refine the estimates. 

Flooded marsh in Everglades National Park

Flooded marsh in Everglades National Park

(Public domain.)

 

Future Steps: None at this time.