Habitat Suitability Criteria for Virile Crayfish, a Non-Native Species in Arizona

Introduction of non-native species can influence survival of native species.  Virile Crayfish Orconectes virilis introduction in the southwestern United States, particularly Arizona, are a serious concern due to their potential negative effect on imperiled native fish and invertebrates.  Current control methods have been unsuccessful in natural stream systems; however, certain habitat parameters might be altered to disfavor crayfish.  Here we show habitat suitability criteria for Virile Crayfish in high elevation Arizona streams.  Future research will compare favored habitat for Virile Crayfish with habitat criteria for other managed species. We sampled streams containing Virile Crayfish using a quadrat sampler to identify occupied and unoccupied locations and measured habitat parameters (water velocity, depth, substrate, in stream cover, overhead cover and temperature) at each location.  For each variable, habitat ranges occupied were compared to those available to assess preference.  Of variables investigated, Virile Crayfish selected only for substrate and temperature (P < 0.0001).  Juveniles were more selective than adults, preferring shallow, slow-moving water.  We hope to use this assessment of habitat suitability criteria as a tool to better understand environmental factors that limit Virile Crayfish and use this information to limit their interactions with other native species, especially Apache Trout Oncorhynchus gilae apache.