Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A triploid grass carp risk analysis specific to Florida.

Abstract

Three hydrilla (Hydrilla verticillata) biotypes are resistant to fluridone, the principal herbicide used in Florida. Because of an anticipated demand for triploid grass carp (Ctenopharyngodon idella), a risk analysis was conducted to examine the use of triploid grass carp to control hydrilla in large (>200 ha), open systems in Florida. An expert panel utilized the Generic Nonindigenous Aquatic Organisms Risk Analysis Review Process developed by the Aquatic Nuisance Species Task Force to assess five hydrilla management options. Specifically, the panel assessed the risk of (1) eliminating all vegetation for three years or more; or (2) vegetation coverage exceeding 50% for five consecutive years. Herbicide application, followed by stocking low levels of triploid grass carp and subsequent herbicide treatment, was considered to be a lower risk option to achieve hydrilla management objectives. The expert panel emphasized the necessity of implementing well-supported system management and monitoring and determining stocking rates on a lake-by-lake basis.