Die studie was uitgevoer om te bepaal of warmwaterspesies soos tilapia (Oreochromis mossambicus) en koi (Ciprinus carpio) gebruik kan word as deel van 'n roterende akwakultuur produksie sisteem in die Wes-Kaap. Drie produksiestelsels (drywende hokstelsel; gronddamme en hersirkuleringseenheid) was ge-evalueer vir beide tilapia en koi produksie. Twee verskillende diëte (tilapia, 32% proteien, 'n lae waarde dieet en koi, 32% proteien, 'n hoë waarde dieet) was ook ge-evalueer vir die effek op koi produksie. Tilapia- en koi vingerlinge was teen dieselfde lading (250/hok) in elke produksiestelsel geplaas. By die begin van die proewe het die tilapia vingerlinge 'n gemiddelde gewig van 60-80g en die koi vingerlinge 'n gemiddelde lengte van 30-40 mm gehad. Die visse is twee keer per dag gevoer en data is op 'n maandelikse basis oor 'n periode van 84 dae versamel. Produksie data vir die tilapia versamel was: 1) die gemiddelde daaglikse toename, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die produksie data versamel vir koi wat twee verskillende diëte ontvang het in drie verskillende produksiestelsels was: 1) die gemiddelde daaglikse toename in lengte, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die resultate van die tilapia studie het aangedui dat tilapia in die hersirkuleeringseenheid het deurgaans 'n swaarder gewig gehad (p<0.05) as die van die drywende hokstelsel en gronddam stelsel. Terwyl die gronddam stelsel weer 'n swaarder gewig gehad het as die drywende hokstelsel behalwe vir April (171,67 / 39,49 vs 159,33 / 22,15). Nieteenstaande die verskil in begin gewig en eind gewig in die guns van die tilapia in die hersirkuleringseenheid teenoor die ander twee stelsels het die GDT tussen die drywende hokstelsel en die hersirkuleringseenheid nie noemenswaardig verskil nie (1,20 / 0,15 vs 1,40 / 0,24). Die tilapia in die gronddamme het egter swakker (p<0,05) gewigstoename van 0,72 / 0,32 g gehad teenoor die tilapia in die drywende hokstesel 1,40 / 0,24 g en 1,20 / 0,15 g van die tilapia in die hersirkuleringseenheid. Tilapia in die gronddamme het dus ongeveer 45% swakker gemiddelde gewigstoename getoon as die van die drywende hokstelsel en hersirkuleringseenheid. Die produksiestelsel het 'n hoogs betekenisvolle invloed (p<0,001) op die groeipotensiaal van tilapia gehad in hierdie studie. Die gemiddelde totale hoeveelheid voer verbruik was nie statisties verskillend tussen die drywende hokstelsel en gronddam stelsel nie (29,83 / 2,66 vs 30,83 / 5,42), maar wel (p<0,05) vir die hersirkuleringseenheid (29,94 / 0,88). Die VOV het nie verskil tussen die drywende hokstelsel en hersirkuleringeenheid, maar daar was wel 'n verskil (p<0,05) tussen hierdie twee stelsels en die van die gronddamme. Die totale gemiddelde mortaliteite van tilapia was die hoogste (p<0,05) vir die drywende hokstelsel in vergelyking met die gronddamme en hersirkuleringseenheid. Die drywende hokstelsel het 14,67 / 14,61% meer mortaliteite gehad as die gronddamme en hersirkuleringeenheid. Die koi studie se resultate dui aan dat die tipe stelsel het 'n hoogs betekenisvolle (p<0,001) invloed gehad op die gemiddelde toename in lengte van die koi vis vir die somerseisoen. Die tipe dieet het geen invloed op die toename in lengte van koi vis vir al drie die stelsels ge-evalueer, maar die interaksie tussen dieet en die tipe stelsel was wel betekenisvol (p<0.05). Die interaksie tussen die tipe dieet en die tipe stelsel was die hoogste vir die groddamme 136,41 / 32,46 mm en 136,25 / 33,08 mm vir beide tilapia en die koi diëte gevoer. Die gemiddelde totale voer wat deur koi visse in die drie stelsels verbruik is, het wel statisties van mekaar verskil (p<0,05). Koi visse in die gronddam stelsel het meer voer verbruik vir beide die tilapia- en koi dieet (31,03 / 2,01 en 29,67 / 3,57) in vergelyking met die (26,35 / 2,44 ; 26,98 / 0,49 en 5,50 # 0,52 en 6,13 / 0,22) vir die drywende hokke en hersirkuleringseenheid stelsels onderskiedelik. Die % mortaliteite was betekenisvol (p<0,05) vir die verskillende stelsels. Koi visse in die hersirkuleringseenheid het die hoogste mortaliteite gehad vir beide die tilapia en die koi diëte (65,50 / 18,07% en 79,50 / 38,27%) terwyl koi visse in die gronddamme die laagste mortaliteite ondervind het (1,20 / 1,20% en 2,33 / 4,89%) vir beide die tilapia en koi diëte. Die koi in die gronddam stelsel het die beste resultate gelewer en dit is ook moontlik om koi 'n lae waarde dieet te voer sonder nadelige effekte op produksie.

Thesis (M. Sc.)--University of Hong Kong, 1963. / Type-written copy. Includes bibliographical references.

The initial aims of the present study were to investigate the problems associated with salt water transfer in Sarotherodon spp. with the objective of maintaining high rates of survival and satisfactory growth rates. Members of the euryhaline commercially cultured Sarotherodon species viz. Sarotherodon aureus, S. mossambicus, S. spilurus, S. niloticus and the hybrids of S. aureus/S. niloticus were used. The specific salinity tolerance and the capability of tolerating direct transfers to specified salinities and the comparative abilities of surviving gradual increases of salinity up to full strength sea water were investigated. The involvement of the plasma osmotic concentration in the osmoregulatory process, and the physiological changes following the direct transfer to salt water were examined with special reference to the possibility of using changes of plasma osmotic concentration as an indicator of fish transferability. S. aureus proved to be best able to withstand salinity changes, though in all cases gradual transfer was required to limit mortalities. Feeding of high dietary sodium chloride diet was evaluated for S. mossambicus and S. aureus/S. niloticus hybrids as a method of stimulating osmoregulatory process prior to salt water transfer. This was found to alleviate only slightly the osmotic stress following direct transfer to a known lethal salinity. Water deterioration and temperature fluctuation during fish transportation are inevitable, especially after long journeys. The effects of water quality deterioration, temperature fluctuation and food deprivation, typical of transport conditions, were studied in combination with salinity transfer effects. Effects were significant in all cases though, of the species studied, niloticus appeared to show the highest resistance to the combined effects. Following full acclimation to full strength sea water, the effects of prolonged exposure to sea water on the subsequent survival, growth rates and food conversion were investigated. S. niloticus and the hybrids of S. aureus/S. niloticus were found to be less tolerant to long-term exposure than the other candidates, which were selected for further detailed study. Light and electron microscopic studies of the gills and chloride cells were carried out in S. mossambicus and S. spilurus. This study showed the modified role of the chloride cells in fresh and sea water environments. Increases in number and developments of the ultrastructure of these cells were observed in sea water adapted samples from both of the species. Consequently the significance of the chloride cells in the osmoregulatory process was discussed. The significance of these results was considered in terms of aquaculture practice and suggestions are made for improved transfer methods in this context.

Digitized by Kansas Correctional Industries

Thesis (Ph. D.)--University of Washington, 1983. / Vita. Bibliography: leaves [201]-228.

No description available.

Winter flounder, Pleuronectes americanus, is being developed for aquaculture in Atlantic Canada. Since larval culture has been successful, research can now address problems at the juvenile stage such as weaning, diet and optimal growth environment. Weaning, a critical stage in culture of any flatfish species, is the switch from live food to an artificial diet. In a three month study, I was able to wean wild young-of-the year winter flounder from live, cultured Artemia onto dry food. Specific growth rates and food conversion indicated the artificial diet was a better food source than Artemia. In a second study, I was able to wean recently-metamorphosed winter flounder reared in the laboratory, onto two artificial diets which differed in price and lipid content. There was no difference between the inexpensive salmonid starter diet and the more costly Nippai diet on growth and survival. In a third study, I examined the effects of temperature and density on wild year 0 and 1 winter flounder reared on dry salmonid diet. There was no effect of density on growth and survival over the ranges tested. Greatest growth occurred at 15$ sp circ$C, although survival was highest at ambient temperature.

No description available.

A rationale is presented for a primary nursing strategy and an on-growing strategy for Clarias gariepinus (Burchell) culture in Africa, thus providing a potential model for the development of culture technology for the species. Existing information pertaining to the production strategies identified is reviewed, highlighting the attributes of African catfish for aquaculture. Some of the current deficiencies and inconsistencies in available information pertaining to controlled hatchery production are addressed. The early developmental stages of Clarias gariepinus are defined, in order to promote consistent use of terminology and help farmers better address the changing needs of their developing stock. The pattern of growth and survival of larvae and fry is investigated at higher stocking densities than those used experimentally to provide a database for planning full-scale commercial operations. Tank design and water flow rates appropriate for Clarias gariepinus in hatcheries are investigated and recommendations made. Finally, in order to promote maximal growth rates of hatchery stocks the maximum daily feed intake of larvae in relation to different feeding regimes is estimated based on rates of gastric evacuation and return of appetite. An overview of the controlled hatchery production of Clarias gariepinus is presented.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains viii, 60 p. : col. ill. Vita. Includes abstract. Includes bibliographical references (p. 42-45).