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Harvest Weight (harvest + weight)
Selected AbstractsEvaluation of Stocking Density and Feeding Regime on Production of Red Swamp Crawfish in Outdoor MesocosmsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2010Robert P. Romaire Seven stocking densities and three feeding regimes were evaluated, in combination, to determine their effects on production and relative condition of red swamp crawfish, Procambarus clarkii, in outdoor mesocosms. Juveniles were grown from November through June at densities of 5 to 35/m2 with either no cultivated rice, cultivated rice, or cultivated rice+formulated pellets as food resources. Crawfish size was influenced primarily by stocking density, survival was equally influenced by density and feeding regime, and yield was affected mostly by feeding regime. Individual harvest weight and survival decreased with an increase in stocking density. Most crawfish exceeded 20 g at 5 and 10/m2 in treatments with cultivated rice, but significant stunting occurred in all feeding regimes at 15/m2 or higher. Survival decreased with increased density, and was significantly less in the no-rice system, presumably from starvation and cannibalism. Mean crawfish yield in rice (1549 kg/ha) and rice+feed (1629 kg/ha) treatments was about 2.5 times higher than in the no-rice treatment (618 kg/ha). Formulated feed did not prevent stunting at high densities, but crawfish provided feed were in better physiological condition. Planted rice with an initial population density of about 10/m2 appears to provide the best combination to maximize both size and yield. [source] Detection of QTL affecting harvest traits in a commercial Atlantic salmon populationANIMAL GENETICS, Issue 5 2009R. D. Houston Summary Genetic variation in performance and quality traits measured at harvest has previously been demonstrated in Atlantic salmon aquaculture populations. To map major loci underlying this variation, we utilized data from 10 families from a commercial breeding programme. Significant QTL were detected affecting harvest weight and length traits on linkage group 1, and affecting waste weight on linkage group 5. In total, 11 of the 29 linkage groups examined showed at least suggestive evidence for a QTL. These data suggest that major loci affecting economically important harvest characteristics are segregating in commercial salmon populations. [source] Growth performance of mixed sex, hormonally sex reversed and progeny of YY male tilapia of the GIFT strain, Oreochromis niloticusAQUACULTURE RESEARCH, Issue 6 2009Norhidayat Kamaruzzaman Abstract The growth performance of three experimental groups consisting of mixed sex fish (control), hormone-treated fish and progeny of YY male tilapia, all originated from the genetically improved farmed tilapia (GIFT) strain was evaluated. Masculinization of sexually undifferentiated fry was achieved by providing a supplement of 5 mg of 17-,-methyltestosterone per kg of feed over a period of 21 days (after sac absorption). Both mixed sex and progeny of YY male groups were fed a standard commercial ration. Mixed sex fish did not deviate significantly (P>0.05) from the 1:1 male to female ratio. Percentages of male averaged 75% in hormone-treated fish and 95% in YY male group over the sampling periods and at final harvest. The effect of sex on weight and length was statistically significant (P<0.001). The model used to analyse weight and length included experimental group and sex in each culture period as the fixed effects, and replicate cages as the random effect. Over the culture period of 141 days, there were no statistical differences (P>0.05) in body weight and length between mixed sex, hormonally treated and progeny of YY males. There were also no significant differences in level of variability in harvest weight between three groups of fish when the data were classified into five categories (=<100, 100 to <150, 150 to <200, 200 to <250 and ,250 g). It is concluded that monosex culture of all male tilapia would be of no advantage over mixed sex culture for the GIFT strain under conditions of cages suspended in earthen ponds. [source] Production and Processing Trait Comparisons of Channel Catfish, Blue Catfish, and Their Hybrids Grown in Earthen PondsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 6 2008Mingkang Jiang Fingerling HS-5 channel catfish, Ictalurus punctatus, NWAC 103 channel catfish, D&B blue catfish, Ictalurus furcatus, HS-5 female channel × D&B male blue catfish F1 hybrids, and NWAC 103 female channel × D&B male blue catfish F1 hybrids were stocked into twenty-five 0.04-ha earthen ponds at 12,500 fish/ha and grown for 277 d. Fish were fed daily at rates from 1.0 to 3.0% biomass based on feeding activity and temperature and adjusted weekly assuming a feed conversion ratio (FCR) of 1.8 and 100% survival. At harvest, 40 fish from each pond were sampled, and all other counted and weighed. Mean survival, growth rate indexes (a), FCR, and skin-on fillet percentages were not significantly different. Mean harvest weights and net production were higher for HS-5 channel and its hybrid than for the NWAC 103 channel, NWAC 103 hybrid, and D&B blue catfish, partially because of their larger mean stocking weights. D&B blue catfish was more uniform in size than NWAC 103 channel and NWAC 103 hybrid. D&B blue catfish was the easiest to seine. HS-5 hybrids and NWAC 103 hybrids had lower mean head percentage and a better processing yield than their parent channel catfish. [source] Effects of Two Densities of Caged Monosex Nile Tilapia, Oreochromis niloticus, on Water Quality, Phytoplankton Populations, and Production When Polycultured with Macrobrachium rosenbergii in Temperate PondsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2007Jason J. Danaher The effects of different densities of caged Nile tilapia, Oreochromis niloticus, on water quality, phytoplankton populations, prawn, and total pond production were evaluated in freshwater prawn, Macrobrachium rosenbergii, production ponds. The experiment consisted of three treatments with three 0.04-ha replicates each. All ponds were stocked with graded, nursed juvenile prawn (0.9 ± 0.6 g) at 69,000/ha. Control (CTL) ponds contained only prawns. Low-density polyculture (LDP) ponds also contained two cages (1 m3; 100 fish/cage) of monosex male tilapia (115.6 ± 22 g), and high-density polyculture (HDP) ponds had four cages. Total culture period was 106 d for tilapia and 114 d for prawn. Overall mean afternoon pH level was significantly lower (P , 0.05) in polyculture ponds than in CTL ponds but did not differ (P > 0.05) between LDP and HDP. Phytoplankton biovolume was reduced in polyculture treatments. Tilapia in the LDP treatment had significantly higher (P , 0.05) harvest weights than in the HDP treatment. Prawn weights were higher (P , 0.05) in polyculture than prawn monoculture. These data indicate that a caged tilapia/freshwater prawn polyculture system may provide pH control while maximizing pond resources in temperate areas. [source] | ||||||||||