Title: Cost-Efficient Management of Aquatic Invasive Species: Application to New Zealand Mudsnails in the Pacific Northwest

By affecting the ecological, pecuniary and aesthetic productivity of ecosystems, invasive species (IS) increase production and management costs to business, while straining public agencies' budgets with monitoring, enforcement and management efforts. Understanding invasion pathways or vectors, and identifying costs and benefits of alternative management strategies are critical to public and private decision making in agriculture, natural resource and recreation industries. This study develops an integrated spatial framework to measure IS risk and cost-efficiency of alternative IS management strategies. For a given spatial unit, the framework weighs expected damages, based on measured IS risk, against the cost of alternative management strategies, i.e. spatial cost minimization. The study then applied the spatial cost minimization framework to the case of New Zealand mudsnails, Potamopyrgus antipodarum, (NZMS) in the Pacific Northwest (PNW) using data from a variety of sources. The first stage of the integrated framework is the measurement of NZMS establishment risk, which is estimated as a combination of anthropogenic introduction risk and habitat suitability risk. Since recreational boats are a main vector to disperse NZMS, the normalized boat flows in the PNW states—Idaho, Oregon, and Washington—are used as a proxy for the anthropogenic introduction risk. An environmental niche model then revealed the relationship between environmental features and NZMS presence, i.e. habitat suitability risk. Results suggest that distance, area size, water body concentration, and accessibility are major determinants of PNW recreational boat flows. Environmental characteristics such as elevation, geologic features