58 March 2012 were randomly taken from a pond, individually weighted and stocked into one of 20, 288 L rectangular tanks (2.4 x 1.2 x 0.1 m). Five treatments with four replicate tanks per treatment were established. Treatments were 8, 12, 16, 20, or 24 female broodstock redclaw per tank, corresponding to 2.8, 4.2, 5.6, 6.9, and 8.3 females/m2. Feeding was similar to the previous experiment and survival and growth were determined 30 days post spawning. Experiment 3: Effect of nursery period and broodstock density on juvenile performance Protocols used were similar to those of the previous two experiments with a few modifications. The experimental design consisted of a 3x3 factorial arrangement. Gravid females (egg stage 5) were randomly stocked into one of 36 rectangular tanks (2.4x 1.2 x 0.1 m; 2.88 m2 bottom area) divided into nine treatments with four replicate tanks per treatment. Treatments were 8, 12, or 16 female broodstock and a 20-day, 30-day or 40-day juvenile nursery period. At the end of each priod, juveniles were counted and weighed. Statistical Analysis Total Juvenile Production, Juveniles/female, Juveniles/g of female, Biomass, Average weight and Survival of juveniles were calculated. Results of the first two experiments were analyzed using one-way analysis of variance (ANOVA) and considered significant at P<0.05. Because of the potential for differential total production of juveniles and differences in average weight among the various nursery periods in Experiment 3, data were analyzed by two-way ANOVA, using number of females and days in the nursery as factors. The data was also sorted by nursery period of juvenile production and average weight. Tukey’s test was used to identify statistically significant differences among treatment means. All statistical analysis was performed using MINITAB software6. Results and Discussion Average egg count per unit weight (g) of female at stage 5 was 7.8±2.15 (mean±SD). Similar results were reported by other investigators where the reported egg count ranged from 7.5-8.7 eggs/g of female (King 1993, Yeh and Rouse 1994, Jones 1995a, Austin 1998). Accordingly, expected juvenile production per gram of female using a 95 percent hatch success was 7.4 juvenile/g of female. Water volume had no effect on the production performance of a hatchery-nursery system, but surface area had an effect and is thus a better variable to use when predicting juvenile production of Cherax quadricarinatus. Additionally, stocking densities of 12 to 20 females/tank with a 30-day nursery period produced the greatest number of juveniles and would thus maximize Total Production without a Mrs. Lidia G. Fournue Guerrero, Mr. Nabor Medina Vasquez . and Dr. Antonio Garza de Yta (second, third and fourth from left) at the AGY Redclaw Hatchery. Round tanks and rectangular tanks where research was performed. juveniles detached, all females were removed from the tanks. All juveniles detached within a 96-hour period. When the last group of juveniles in a tank had detached, the tank was managed as a nursery system for 30 days. Juveniles were offered ground commercial pelleted feed (30 percent protein, 8 percent lipid) at 10 percent body weight initially and later adjusted based on observations of uneaten feed. Uneaten feed was removed once a week by siphoning the bottom of the tanks. At the end of the experiment, all juveniles were counted and weighed. Experiment 2: Effect of female stocking density on juvenile growth and survival The methodology used was similar to that of experiment 1 with a few exceptions. Females with similar stage eggs
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