Overlooked Invaders? Ecological Impacts of Non‐Game, Native Transplant Fishes in the United States

Abstract

Nonnative fishes can cause ecological impacts as invasive species, but identifying which nonnative species have harmful impacts is critical to prioritizing management and policy responses. Here, we characterized the state of knowledge on the impacts of a possibly overlooked group of invasive species in the United States: non-game native transplant (NGNT) fishes. We propose that NGNT fishes may be understudied relative to nonnative game fish and exotic species introduced from outside of the country.Only 14% of 220 freshwater NGNT fishes in the United States have been studied for possible negative impacts. We found that researchers have neglected to study impacts of many widespread NGNT species, and some regions with high NGNT species richness have had no studies of the impacts of any NGNT species. Genetic and ecosystem impacts of NGNT fishes have been particularly neglected relative to population and community impacts. We recommend that researchers and funding entities direct their attention to prospective impacts of the most widespread NGNT species in the least studied U.S. river basins to identify which of these fishes require prevention and management as invasive species.

Niche conservatism and spread explain introgression between native and invasive fish

“…For well‐studied organisms like the invasive O. mykiss and native O. clarkii lewisi system, hybridisation and introgression outcomes have been well‐attributed to propagule pressure from fish stocking (Bennett et al., 2010), habitat modification by damming or impoundment (Ardren & Bernall, 2017) and temperature tolerances of parent species (Muhlfeld et al., 2017). By contrast, environmental drivers of hybridisation and introgression with invasive species are minimally known for most non‐game or other neglected native species (Hartman & Larson, 2023; Rypel et al., 2021).…”