Factors Influencing the Presence of Non-Native Fish Species in Adirondack Lakes

Identification of factors that make lakes vulnerable to invasion of non-native fishes can help identify ecosystems likely to be invaded and species that could become invasive.  We evaluated whether private land ownership and restrictive land use designations influenced the number of non-native, native, and total number of species in 1401 lakes in the Adirondack region of New York.  Variation associated with chemical and physical characteristics of lakes was accounted for using principle components analysis.  Hypotheses were tested and nonlinear trends associated with habitat, acidity, productivity and watershed position were described using a generalized additive model.  The number of non-native, native, and total fish species in study lakes was positively associated with available habitat and lake productivity, and negatively associated with acidity. Fewer native species were found in lakes surrounded by restrictive land used designations, but land use designations had no impact on numbers of non-native species or the total number of species present.  Approximately 1.3 fewer native species were found in lakes with land use restrictions than without.  Land use restrictions had no effect on the number of non-native or total species present.  Private ownership had no impact on the number of native, non-native, or total fish species present.