摘要:

AbstractFarmed freshwater prawn production globally expanded by a factor of 3.5 in the 7 years from 1984 to 1991 but declined by 17% to 31 235 tin 1992. This was caused by a 53% reduction in the output of Taiwan due to disease and in‐breeding problems, partially compensated by increases elsewhere, notably in India and Vietnam. This paper reviews the scientific literature published between 1989 and 1994 on the culture of the freshwater prawnMacrobrachium rosenbergii(De Man 1879) and summarizes earlier work. Broodstock and larval studies, nutrition, grow‐out management, genetics, integrated aquaculture and disease and water quality are covered. Finally, a brief summary of the status and characteristics of prawn culture in the major farming locations is presented, together with some comments on the opportunities and constraints for further developm

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00859.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study analyses the combined effects of organic and inorganic fertilization and of feeding with pellets on fish performance and water quality in a polyculture of common carp.Cyprinus CarpioL., silver carp.Hypophthalmichthys molitrix(Val.), grass carp.Ctenopharyngodon idella(Val.) and hybrid tilapia,Oreochromis niloticusL. xO. aureusStetndachner. Experiments included six treatments, which are combinations of inorganic fertilisation (daily or fortnightly), manuring (supplied or not), feed pellets (supplied or not) and density of phytoplanktivorous fish species (high‐density treatments with 50% more hybrid tilapia and 300% more silver carp than low‐density treatments). The effects of the management procedures on fish weight, growth, survival and yield. plankton abundance, water quality, and their complex interactions at the different levels of the natural food web were analysed.The hypothesis that daily fertilization should increase algal production, which in turn should sustain a higher density of phytoplanktivorous fish, proved to be correct within certain limits. Algal reproduction rate was higher under daily fertilization, pointing to better supply of food for herbivorous fish, while algal biomass was similar under both fertilization regimes, pointing to the utilization of that algal food supply. The increased algal food supply sustained a 50% density increase of the omnivorous tilapia, but not the 300% density increase of the grazer silver c

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00860.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA single heat shock of 28°C for 10 min, applied 15 min after water activation to five different batches of brown trout,Salmo truttaL., ova and replicated within one batch produced triploid rates ranging from 22% to 100% and variable survival to hatch ranging from 9.4% to 47.9%. Variability was greater among batches than among replicates. In general, the treatment reduced survival to hatch by 50%. The range of triploid yields obtained from a single heat shock regime is discussed in terms of potential advantages to aquaculture

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00861.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractStocking and harvest data from 45 grow‐outs of the crayfishCherax tenuimanus(Smith 1912) on a commercial farm were analysed to give predictive equations for survival, mean weight and individual weights of crayfish at harvest. Density dependence was a major factor influencing variation in survival and mean weight. Harvest mean weight decreased, and biomass increased, with density. The crayfish price ($ kg−1) employed to estimate the market value of harvested crayfish increased with individual weight from a minimum saleable weight of 40 g. For grow‐out of 0+ year‐olds for 1 year, the market value was a maximum at low stocking densities of 1.5‐2.0 m−2. Further grow‐out for 1 year of the unsaleable weight range (20‐40 g) of 1+ year‐olds, gave a harvest value which increased with stocking density. Comparison of predicted and actual cohort numbers and mean weights for a further 1 5 harvests showed no bias in prediction and a mean precision level of 16% for numbers and 11

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00862.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY