Factors influencing detection of invasive Red Swamp Crayfish Procambarus clarkii (Girard, 1852) in Michigan ponds

Red Swamp Crayfish Procambarus clarkii (Girard, 1852) (RSC) are a highly invasive species established on five continents. Recent detections of RSC populations in several locations in Michigan, USA spurred action to develop trap-based early detection and response plans based on the best available science, however, few recommendations are available concerning important sampling logistics such as timing and density of deployed traps. We surveyed 231 waterbodies (mainly lentic systems with relatively few small lotic systems) for RSC in two invasion zones in southern Michigan. We used Bayesian hierarchical models to evaluate baited traps for detection of RSC invasions, and qualitatively evaluated feasibility of eDNA metabarcoding for enhancing trap-based detection strategies. While overall occupancy was low, predicted detection probabilities with baited traps ranged from 27 to 98