Production Management of Double-Net Tilapia Oreochromis spp. Hatcheries in a Eutrophic Tropical Reservoir

Abstract.— A floating, double-net hatchery system for a red tilapia hybrid Oreochromis spp. was developed and tested in a eutrophic reservoir in West Java, Indonesia. Objectives of the studies were to test the effects of different male and female broodstock rotation times on fingerling production and compare production of the double-net system with other studies using a multiple regression model. Two experiments (EXP1 and EXP2) were conducted in four separate double-net hatchery systems comparing three broodstock rotation times over 12 spawning periods in EXP1 and 21 in EXP2. In both experiments, shorter broodstock rotation times (14–16 d in EXP1 or 10–15 d in EXP2) produced significantly ( P < 0.05) higher numbers of fingerlings (6.24 in EXP1 and 14.52 fingerlings/female per d in EXP2). A multiple regression model was developed to summarize results of six studies which included 31 spawning periods. A significant ( r² = 0.651, P < 0.05) relationship was found between tilapia seed production in net hatcheries as the dependent variable and initial female broodstock densities (−), initial female body weight (−), female/male stocking ratio (−), and feed protein content (±) as independent variables.