Effects of winter temperature and flow on a summer-fall nursery fish assemblage in the Chesapeake Bay, Maryland

In temperate estuaries, nearshore nursery fish assemblages are influenced by environmental conditions that are :present during and prior to the period of juvenile fish occurrence. An intensively sampled site (Patuxent River estuary) in mesohaline Chesapeake Bay provided 9 years of data for relating previous and current environmental variables with juvenile fish assemblages. Canonical correspondence analysis identified temperature and flow from the previous winter (January-March) and week and year of the assemblage sample as the most influential variables. In contrast, environmental variables at the time of sampling were not identified as important. High summer-fall abundances of Atlantic silversides Menidia menidia, striped bass Morone saxatilis, white perch Morone americana, and Atlantic needlefish Strongylura marina were positively associated with low winter temperatures and high winter flows. High abundances of bluefish Pomatomus saltatrix, spot Leiostomus xanthurus, bay anchovy Anchoa mitchilli, and northern puffer Sphoeroides maculatus were associated with low winter flows and high winter temperatures. The mechanisms by which winter conditions affect the summer-fall nursery fish assemblage were not directly addressed in this study, but winter conditions can affect subsequent spring and summer estuarine production, spawning and recruitment phenology, and distributions of juvenile fishes.