CONDITIONING AND INDUCED SPAWNING OF THE RED DRUM (Sciaenops ocellata) UNDER VARIED CONDITIONS OF PHOTOPERIOD AND TEMPERATURE

Abstract Vitellogenesis, culminating in spawning, was artificially induced in red drum (Sciaenops ocellata) using photoperiod and temperature as exogenous stimuli. Maturation was induced out of season during the normal refractory period of red drum found in central Florida waters. Four regimes were compared to a control. Three regimes culminated in advanced vitellogenesis and spawning. A semi‐natural regime induced spawning in 129 days, an abbreviated decelerating regime induced spawning in 83 days, and an abbreviated accelerating/decelerating regime induced spawning in 117 days. Functional maturity of females was defined by analysis of vitellogenic stage frequency and oocyte diameter frequency. Ovarian biopsies were taken by catheter at 30‐day intervals during experiment I, and 60‐day intervals during experiment II. For a 90‐day period in 1976, 4 females spawned 8.43 million eggs. For a 100‐day period in 1977, 8 females spawned 4.41 million eggs. Fertilization success was always greater than 99% and mean hatching success was 93.40% for all spawns.