ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00952.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of introduction of common carp,Cyprinus carpio(L.). in polyculture with major Indian carps and silver carp were studied in fertilized and fed earthen ponds in Mymensingh, Bangladesh. Bottom‐dwelling common carp were found to exert an influence on the quality and quantity of planktonic food organisms. The presence of common carp significantly increased (P<0.05) the growth of other carps including the bottom‐feeder mrigal.Cirrhinus mrigala(Hamilton). A significantly higher fish yield (P<0.05) was observed in the fish ponds containing common carp when the combined yields of all species in three treatments were compa

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00953.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper reviews some of the environmental concerns which have been expressed regarding the use of chemicals in aquaculture. It discusses recent developments in legislation and technology which could be used to improve the future risk assessment and management of such chemicals.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00954.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractLaboratory experiments on juvenile turbot.Scophthalmus maximus(L.), were carried out under controlled temperature (12°C) and feeding regimes in a flow‐through system. Monitoring of total ammonia nitrogen (TAN) and urea nitrogen (Urea‐N) was performed through continuous sampling of the effluent sea water. The effects of ingested nitrogen levels on TAN and Urea‐N daily and hourly excretion rates were studied. Strong relationships were found between ingested nitrogen, and both TAN and Urea‐N excretion for both daily and hourly maximum excretion rates. Turbot showed a low metabolic activity, confirmed by low excretion levels. Daily patterns for TAN and Urea‐N production were different, suggesting specific physiological phenomenon for urea excretion mechanisms. The question of whether turbot are partly ureotelic or ureogenic is

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00955.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractNutrient digestibility and amino acid availability were assessed in tilapia,Oreochromis niloticus(L.), fingerlings fed diets containing soybean flour (SF): poultry meat meal (PMM) blends (25:75, 50:50 and 75:25), and 0.5 or 1.0% Cr2O3. Although there was variability in individual amino acid availability, average availability was in agreement with the pattern of overall protein digestibility. The best lipid, protein digestibility and amino acid availability values were obtained in the 75:25 SF:PMM blend and 0.5% Cr2O3treatment, which corresponded to the lowest level of faecal crude protein while the best ash digestibility was observed with 25:75 SF:PMM blend and 1.0% Cr2O3. Chromic oxide inclusion level appeared to affect nutrient availability. Increased marker level might have resulted in decreased nutrient digestibility coefficients. Protein and lipid of diets containing more soybean flour seemed to be more digestible than those of poultry meat meal while the reverse was the case for ash.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00956.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractBenthic macrofaunal community changes are used extensively to monitor the impact of polluting discharges to the marine environment. Regulatory and pollution control authorities have recognized the particular value of the well studied and reported responses of infaunal communities to organic pollution including wastes from aquaculture. Benthic systems are embraced in both the consent (licence) to discharge and monitoring procedures for marine cage fish farms in the Clyde River Purification Board's (CRPB) area. The relevant protocols of the CRPB are described and data are presented from impact studies throughout west central Scotland, focussing on the sedimentary environment (macrobenthos, organic carbon and redox: Eh). Macrobenthic infaunal responses, though not fully understood, were considered to provide the best measure to date of determining the impacts of organic wastes from cage fish farming and a possible way forward in developing benthic Environmental Quality Standards (EQSs) for aquaculture. Some patterns in physico‐chemical data were identified, but frequently, the relationship both with benthic infaunal data and each other were inconsistent. Grossly impacted faunal communities varied little between sites and could readily be described by the simple community determinands of abundance (A), species richness (S) and Shannon Weiner diversity index (H). Moderate to lightly impacted zones were less easily defined but detailed faunal studies have allowed the selection of some widely distributed marker species. However, site‐specific observations emphasized the site individuality and difficulties of setting EQSs across the industry. Using the principles of enhanced species populations and by identifying marker species, measurable impacts were found to extend further than previously reported. In naturally enriched systems, like the Firth of Clyde and some sea lochs, difficulty in separating slight effects from background was experienced. Continued monitoring and impact assessment, as well as building a better biological data base, may help develop appropriate benthic EQSs relating to aquacult

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00957.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAquaculture, for better or worse, depends in part on drugs for the prevention, control and eradication of a variety of diseases. The US Food and Drug Administration's Centre for Veterinary Medicine, through the Federal Food, Drug and Cosmetic Act, strictly controls the approval and use of drugs in animals, including aquatic animals. Laws and regulations exist that regulate the investigational use and approval of new animal drugs for all animals. However, in reality, these mandates must be uniquely interpreted for aquatic species. Very few drugs are approved for use in aquatic species. There is a growing effort by non‐traditional sponsors (aquaculturists as opposed to pharmaceutical firms) to gain approvals for several new animal drugs. Simultaneously, the federal government, including the Centre for Veterinary Medicine, is working aggressively with the private and public aquaculture sectors to facilitate submission and subsequent approval of new animal drug applications. The drug approval procedures and requirements for aquatic animals are discussed. Special attention is given to their similarities and differences, relative to traditional terrestrial animal

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00958.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIncreasing stocking densities in catfish,Ictalurus punctatus(Rafinesque), aquaculture are making maintenance of water quality a crucial element of production strategy. A bioeconomic simulation model for catfish has been adapted to assess alternative feeding restriction management strategies for US catfish aquaculture operations. The current model includes five decision variables: feeding rate, diet quality, stocking weight, stocking date, and length of growing season. The growth model follows a bioenergetics approach, where the balance between energy intake and energy expenditure determines fish growth. The purpose of this analysis was to simulate changes in production practices resulting from water quality restrictions. Model simulations indicate that restricting maximum daily feeding allowance to maintain higher water quality will actually increase feed requirements to reach a harvestable fish size. In addition, as producers increasingly attempt to spread harvests throughout the year, both for their own cash flow needs and the consistent supply requirements of processors, restricting daily feed allowance will make summer harvests particularly difficult.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00959.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractNutrient discharges from fish farms can be determined retrospectively, simply and with a high degree of accuracy from records of fish production and feed conversion ratios (FCR), combined with chemical analyses of feed and fish. Prospective prediction of the inputs (via feed and outputs) via production and discharges) of given chemical elements, on a daily basis and over longer periods of time, would represent a valuable management tool for farmers, and for regulatory and planning authorities. A dynamic model is presented for Atlantic salmon,Salmo salarL., which integrates biomass, growth rate. FCR. and nutrient retention and discharges in relation to feeding rate, diet composition and environmental factors. In view of the importance of feeding rate on growth, FCR and nutrient discharges, three simulation alternatives were modelled; namely, feeding 50%. 75 or 100% of the estimated maximum daily ration of a specified diet to salmon smolts of 80 g initial weight over a period of one year in sea water. The 50 and 75% rations, in comparison with 100% ration, showed dramatic reductions in fish weight after one year (0.4 and 1.4 kg versus 3.3 kg). The discharges of nitrogen (N) and phosphorus (P) per unit biomass production were reduced to some extent in the first months of the simulation period, and thereafter, there were no clear differences in discharges of N and P per unit biomass at the three ration levels. However, the accumulated N and P discharges per unit weight gain were slightly increased on the 75% ration, and two‐fold higher on the 50% ration compared to the 100% ration. The FCR was also higher in fish fed the lower rations. The simulation result indicates that reduced ration is not effective strategy for minimizing nutrient discharges from fish farms. In order to control discharges within any limits and to utilize the resources optimally, it is better to adjust the biomass on the farm and to feed the fish to appetite, at which growth rate is maximum and FCR is minimu

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00960.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY