Foraging potential of larval American shad and river herring in Lower Roanoke River and Albemarle Sound, North Carolina

Zooplankton composition and abundance was quantified in the lower Roanoke River and Albemarle Sound, North Carolina.  Spatiotemporal overlap between larval American shad Alosa sapidissima and river herring (alewife A. pseudoharengus and blueback herring A. aestivalis) and their size-appropriate prey was evaluated to determine if larval Alosines in this system are food limited.  Samples were collected weekly at 19-stations March through June 2008-09 in three nursery habitats:  river, delta, and sound.  For both years larval Alosine abundances were highest in river (17.6 ± 2.4 larvae 100 m^-3) and lower in delta (5.3 ± 0.7 larvae 100 m^-3) and sound (2.9 ± 0.3 larvae 100 m^-3).  Zooplankton exhibited the opposite trend with highest abundances in the sound (19,476 ± 10,566 individuals per m^-3) followed by river (5,362 ± 3,622 individuals m^-3) and delta (4,286 ± 3,306 per m^-3).  The most common taxa are rotifers (34.9%), copepod nauplii (34.6%), and adult Calanoid copepods (20.6%) with mean body widths of 96.61 ± 43.35 µm, 94.08 ±26.73 µm, and 214.94 µm ± 81.19 respectively.  Mouth gape models are being developed to determine what percentage of available zooplankton fall within optimal prey size range for larval shad and herring.