A multivariate meta-analysis approach was used to identify strong multispecies fish recruitment patterns in Chesapeake Bay, 1966-1998 and to relate these patterns to synoptic-scale, interannual atmospheric circulation variability. Five independently collected, young-of-the-year fish abundance data sets were individually analyzed using principal components analysis (PCA). Despite differences in survey gear, sampled habitat, and sampling location within Chesapeake Bay, a negative relationship between spring-spawning anadromous and wintertime coastal shelf spawning species emerged as the strongest pattern within each data set. This Chesapeake Bay Anadromous/Shelf Spawning (CBASS) recruitment pattern remained virtually unchanged when either lowess or first-differencing were used to remove autocorrelation from each species’ recruitment series prior to PCA.

Because the CBASS pattern varied synchronously throughout Chesapeake Bay, synoptic-scale climatic variability was considered to be a likely forcing mechanism. To investigate this possibility regionally dominant sea level pressure (SLP) patterns during the months March-May were identified using a temporal synoptic classification method. Regional gridded daily SLP (bounded by 25-50 degrees N latitude and 55-90 degrees W longitude) was used in this classification proceedure to characterize dominant SLP patterns during the winter-spring transition period. This method also provided annual time series of monthly frequencies for each of these patterns. The spring transition period was chosen because anadromous and shelf-spawning CBASS species migrate to, and utilize, their respective Chesapeake Bay nursery habitats during these months.

Regression tree and stepwise linear regression models each strongly indicated that the sign and magnitude of the CBASS pattern is dictated by the relative dominance of two regional circulation patterns occuring during March. When the (normally summer-dominant) Azores-Bermuda High pressure system occurs more frequently during March, relative to the (generally winter-dominant) Ohio Valley High, wintertime coastal shelf spawning fishes such as spot (Leiostomus xanthurus) and Atlantic menhaden (Brevoortia tyrannus) recruit strongly to the Bay, while anadromous recruitment is weak. Conversely, when the Ohio Valley High is frequent and the Azores-Bermuda High is not during March, the sign of the CBASS pattern reverses indicating that anadromous and semi-anadromous fishes, such as striped bass (Morone saxatilis), white perch (M. americana), and blueback herring (Alosa aestivalis) recruit strongly, while shelf spawner recruitment is weak.

River-specific, multivariate analyses of hydrographic, meteorological, zooplankton and fish recruitment time series for three major tributaries of Chesapeake Bay suggested a climate-forced, multispecies variant of Cushing’s match-mismatch hypothesis is responsible for these patterns. Timing of the winter-spring seasonal transition appears to impact nursery area suitability and extent for the two CBASS species groups differentially, so that a late transition favors anadromous fishes and their preferred zooplankton prey while an earlier spring favors shelf spawning species and their prey.