Quantifying imperfect detection in an invasive pest fish and the implications for conservation management

► Surveillance programmes of invasive species management are designed to rapidly detect new introductions. ► The probability of detecting an invasive fish according to known densities and different sampling methods was investigated. ► At low densities, no sampling method could detect them; overall, baited traps were the most effective detection method. ► This has consequences for surveillance and eradication evaluations as they suggest detection at low densities is difficult.