Midwest Fish & Wildlife Conference 2017

AUTHORS: Justin Wegner, Mark Luttenton - Annis Water Resources Institute

ABSTRACT: Invasion of aquatic invasive species can be described by two stages: the primary introduction to a novel environment where it establishes a reproducing population and secondary range expansion as the population spreads within a system or is introduced to new systems via natural or abiotic vectors. This pattern of invasion is exemplified in the Great Lakes Watershed by invasive species such as Sea Lampreys, Zebra Mussels, and Round Gobies. In 2015, the New Zealand Mudsnail (NZMS), was discovered in Michigan’s Pere Marquette River indicating that NZMS have begun secondary range expansion. In 2016, during annual macroinvertebrate surveys we discovered a population of NZMS in the East Branch Au Sable River. Macroinvertebrate surveys indicate that NZMS density in the East Branch Au Sable River has increased relatively rapidly in a short period of time. Increases in NZMS density was observed at the apparent introduction site and sites downstream from that location. Additionally there is evidence that NZMS have spread to the Main Branch of the Au Sable below its confluence with the East Branch.  These preliminary findings provide the first estimates of NZMS population growth in a Midwestern stream, and highlights the challenges managers face in controlling the spread of aquatic invasive species once they have become established.