do larval bay anchovy (Anchoa mitchilli) show selective tidal-stream transport?
Bay anchovy (Anchoa mitchilli) have been reported in several systems to display net up-estuary larval movements, against the mean flow. However, the means by which such transport occurs is poorly understood. We address how estuarine circulation and larval behaviors serve to transport larvae of the bay anchovy. In two successive summer seasons, we conducted multiple near-synoptic samples of larval distributions and water column structure along a 45-km section of the middle Hudson River estuary. The analysis focuses on patterns in the vertical distribution of larvae that may help explain transport, and the along-river distribution of different ontogenetic stages. The prediction that post-flexion larvae induce selective tidal-stream transport (STST) by vertically migrating in conjunction with tidal or diel cycles was tested via harmonic regression. Larval concentrations and average larval depths often varied with tidal stage. Maximum concentrations tended to occur at times of slack water,
