Exploring spatial and temporal variation in the early life history of American shad and river herring

Spatial and temporal overlap between larval fish and their prey is thought to have important effects on growth, survival, and recruitment success.  The goal of this project was to investigate the ecological processes that influence recruitment of American shad Alosa sapidissima and river herring (alewife A. pseudoharengus and blueback herring A. aestivalis) to nursery habitats within Roanoke River and Albemarle Sound, North Carolina.  Larval fish and zooplankton were collected weekly at 19-stations from March through June (2008 – 2009).  Alosines were collected at all stations; although distribution and density varied spatiotemporally.  Larval abundances (number/100 m³) peaked in April of each year with 13.0 ± 3.0 for 2008 and 62.6 ± 12.8 for 2009.  For both years, larval abundances were highest within the main stem of the lower Roanoke River (17.6 ± 2.4) as compared to the river delta (5.3 ± 0.7) and Albemarle Sound (2.9 ± 0.3).  Zooplankton abundances were highly variable, ranging from 997 to 33,384 individuals m^-3 with the highest abundances in Albemarle Sound and lowest abundances in Roanoke River.  The results of this study will be used to determine whether match:mismatch regulation could exist in riverine environments with low or patchy distributions of food.