Fish Hatchery Management - fisheries & aquaculture

164 FISH HATCHERY MANAGEMENTOvenipe Eggs t hr. (50X)Note Breakdown at InnerSurface of ChorionOverripe Eggs lX hrs. (50X)Breakdown at InnerSurface of Chorion PersistsOu*ip. Eggs 2 hrs. (50X)Note Deterioration Con$nedto One-Half of EggOu*ip. Egg 16 hrs. (20X)(Dark Areas Appear WhiteUnder Microscope)FIcunn 55, Development of striped bass eggs that become overripe before ovulation.(Courtesy Jack D, Bayless, South Carolina Wildlife and Marine ResourcesDepartment.)As ovulation occurs, eggs of striped bass become detached from theovarian tissue. They are deprived of parental oxygen supply, and anoxiacan result in a short period of time if the eggs remain in the body. (Thisalso is true for grass carp.) If eggs flow from the vent when pressure is appliedto the abdomen, at least partial ovulation has occurred. The maximumperiod between ovulation and overripeness is approximately 60minutes. The optimum period for egg removal is between 15 and 30minutes following the first indication of ovulation. Eggs obtained 30minutes after initial ovulation are less likely to hatch.Prior to manual stripping, female striped bass should be anesthetizedwith quinaldine sprayed onto the gills at a concentration of 1.0 part per