Macrophyte encounter rates on watercraft using boat launches in the Finger Lakes region of New York State

Brown WP, Beck-Andersen S, Cleckner LB. 2025. Macrophyte encounter rates on watercraft using boat launches in the Finger Lakes region of New York State. Lake Reserv Manage. 41:270–280. Watercraft inspection stewards in the Finger Lakes region of New York State educated boat operators about the identification and effects of aquatic invasive species and inspected watercraft and trailers entering and exiting waterbodies. In addition to recording and removing all macrophytes encountered, stewards noted intended activity on the water, type of watercraft, watercraft direction (launching or retrieving), the name of the waterbody, steward, and launch, with the date and year. Launches were categorized into one of 8 compass directions relative to the waterbody’s center, as prevailing winds may influence the presence of macrophyte fragments. From 2021 to 2023, 58 stewards conducted 79,326 inspections at 23 launches. Using a mixed effects generalized additive model, we analyzed 9 variables to assess their mutual influence on macrophyte encounter rates on watercraft and trailers. Date was smoothed with a cubic spline, and year was included as a random effect. The final model, selected based on the Akaike information criterion (AIC), included direction, activity, type of watercraft, launch, steward, date, and year, explaining ∼30% of deviance overall. Direction alone explained ∼18% of the deviance: Macrophyte encounter rates on watercraft and trailers exiting waterbodies were 5.5 times higher than on those entering (41% vs. 7.5%). Future research should examine relationships between encounter rates and seasonal biomass phenology, quantify separate encounter rates for watercraft and trailers, and evaluate macrophyte management strategies at launches.