Effects of Introduced Blueback Herring Alosa aestivalis in a Landlocked Reservoir in Alabama

Blueback Herring Alosa aestivalis were first discovered in Lewis Smith Lake, Alabama in 2010 and have now spread to other reservoirs.  Responses elsewhere in the southeastern U.S. have demonstrated that Blueback Herring can compete with other fishes for zooplankton at multiple life stages.  Alternately, introductions might increase prey availability for piscivores and increase piscivore growth and condition.  We sampled all life stages of Blueback Herring and resident sport fishes in Lewis Smith Lake over 2 years (2013-14).  High diet overlap of Blueback Herring and both larval Lepomis spp. and adult Threadfin Shad Dorosoma pentenense for zooplankton prey suggests a potential for competition at multiple life stages.  We observed significant increases in relative weights of adult Alabama Bass Micropterus henshalli and Largemouth Bass Micropterus salmoides (as well as a non-significant increase for Striped Bass Morone saxatilis).  Hydroacoustic analyses confirm that Blueback Herring are abundant in Lewis Smith Lake; in addition, we found introduced populations in two other Alabama reservoirs (potentially with high abundances based on hydroscoustics sampling).  There is a complex mix of positive and negative responses to Blueback Herring introductions, and additional time will be required for many of these effects to be fully manifested.