Northern Snakehead relative abundance in four Virginia tidal creeks over 20 years following colonization

Objective Newly introduced fish may negatively impact native and beneficial naturalized fish populations, and one factor driving potential adverse effects is abundance of the colonizing organism. We sought to evaluate trends in relative abundance of Northern Snakehead Channa argus for two decades following colonization in four Virginia tributaries of the freshwater, tidal Potomac River system near Washington, D.C. Methods We extracted catch per unit effort (CPUE) data from a long-term temporal database and applied a candidate model framework comparing multiple linear and nonlinear temporal trend structures to evaluate support for alternative relative abundance trajectories. Results Quadratic and log-transformed quadratic models received similarly strong support as both described unimodal temporal patterns and indicated increases in CPUE during the mid-2000s through early 2010s, followed by modest or substantial declines in subsequent years. Model predictions for magnitude and timing of peak CPUE for all creeks except Aquia Creek were nearly identical, with peaks occurring in 2015, about a decade after discovery. Conclusion Models and empirical data, though not perfectly synced, both suggested that Northern Snakehead relative abundance declined following apices in the mid-2010s.