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enclosures was sampled again on October 8, 2002. The razorback sucker population outside the enclosures was estimated using the Peterson, and the Schumacher and Eschmeyer methods described in Krebs (1999). Bonytail outside the enclosures were estimated using the Darrock estimator [M(t)] from the program CAPTURE. The control enclosure was seined repeatedly until all fish were removed. An underwater video camera was used to record fish behavior, predator avoidance, and use of cover. RESULTS Water Quality Measurements Spring flood flows peaked at 7,570 cfs, (214 m3 /sec) far below the magnitude needed to connect the river to The Stirrup floodplain (13,500 cfs or 283 m3/sec). Due to low flow, river ~ water was pumped into the floodplain from the river in late April and provided a maximum depth in excess of 1.0 meter within study enclosures. Following an initial drop in depth to 0.93 m in the fish enclosures, water elevation was increased to 1.06 m and maintained at approximately 1.0 m through the study. Water quality in the Stirrup was conducive to growth of age-0, warm water fish with recorded temperatures ranging from 19 to 28'C and averaging 25.4' C (Figure 1.). Dissolved oxygen rarely dropped below 5.0'mg/1 at any time of day during the study when data were collected (Figure 1.). Zooplankton densities were dramatically influenced by the presence of fish. The zooplankton density in the floodplain outside the study enclosures showed a typical floodplain rapid increase up to 400 zooplankton per liter. This was followed by a subsequent decline to between 30 and 50 z/1 following the appearance of vascular plants (Figure 2.). Zooplankton density outside the fish enclosures also showed a small but consistent increase mid summer, f coincident with pumping activity to maintain water elevation. The spring zooplankton peak in r 7