Eggs of striped bass and white bass were subjected to hydrostatic pressures of 5,000, 6,000, 7,000, and 8,000 PSI for a duration of 5 minutes (2.5 minutes for 8,000 PSI) at 29, 45, or 55 minutes after fertilization. The most effective pressures for producing tetraploidy in white bass were 5,000 and 6,000 PSI and for striped bass 7,000 and 8,000 PSI. Late in the spawning season, only 45- and 55-minute treatments were effective for producing tetraploidy. The relative hatch of eggs subjected to hydrostatic pressure for tetraploid induction was 55% of controls. Original and reciprocal striped bass x white bass hybrid eggs were subjected to hydrostatic pressures of 6,000, 7,000, and 8,000 PSI, applied 2 to 7 minutes after fertilization for durations of 2 to 5 minutes. Several treatments produced triploids; however, 8,000 PSI was the most effective pressure (50% triploid induction) when initiated 2 or 7 minutes after fertilization for a duration of 3 to 5 minutes. The relative hatch of eggs treated for triploid induction was 63% of controls.