R. W. HORTON, R. F. SHAW, J. C. COPE, AND M. C. BENFIELD, Louisiana State University, Coastal Fisheries Institute, Wetland Resources Bldg., Baton Rouge, Louisiana 70803, USA

We conducted a field test of a recruitment enhancement hypothesis for postlarval brown shrimp Penaeus aztecus in a Louisiana estuary. The postulated mechanism involves the influence of tidal and wind-forced currents generated by atmospheric cold fronts on postlarval shrimp. Shrimp are hypothesized to use changes in water temperature and salinity associated with cold fronts to elicit either a passive or behavioral response in combination with a diel activity cycle. We are investigating the linkage between observed transport under astronomically-driven flows ("normal tides") and meteorologically-driven flows. Near surface and near bottom plankton collections were taken 8 times each day for a 90-day period from 1 Feb.-30 Apr. 1994, in Oyster Bayou, a tidal pass connecting the Gulf of Mexico with Fourleague Bay, Louisiana. February samples indicate an interaction between postlarval brown shrimp abundance and atmospheric cold front passages. We are presently determining the temporal, vertical, diel and tidal abundance of brown shrimp as they relate to water flux for the remaining two months.