Strategic conservation of an imperiled freshwater mussel, the Dwarf Wedgemussel, in North Carolina

Abstract

To be effective, managers of imperiled species must face the unavoidable tradeoff between conservation benefits and constrained budgets and must not be paralyzed by scientific uncertainty. Decision analysis can help meet these challenges when used to develop cost-effective strategies to recover or improve the status of species. The U.S. Fish and Wildlife Service, along with state partners, developed a structured decision analysis to guide conservation of Dwarf Wedgemussel (Alasmidonta heterodon) in North Carolina. The Dwarf Wedgemussel is federally listed as endangered, and North Carolina is the southern-most extent of its range, where small and vulnerable populations occur in the Tar and Neuse River basins. The main threat in the Neuse River basin is habitat loss due to anthropogenic land use changes. In contrast, the Tar River basin primarily has been affected by recent drought and stream habitat loss due to beaver impoundments, although habitat has been somewhat buffered from development. A collaborative team used multiple-objective decision analysis to compare the ability of conservation strategies to maximize species persistence while accounting for uncertainty in management effectiveness and variation in in the importance of different management objectives. The decision analysis helped managers evaluate tradeoffs regarding Dwarf Wedgemussel distribution within the Neuse River and Tar River basins. The most cost-effective and robust strategies traded off some opportunity for persistence in the Neuse River for protection of populations in the Tar River basin. The decision analysis is being used to guide efforts to conserve Dwarf Wedgemussel in North Carolina, although challenges continue due to constrained budgets, workload management, and limited regulatory tools.