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  • Articles  (180)
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  • Iranian Fisheries Science Research Institute  (177)
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  • 1
    Publication Date: 2021-05-19
    Description: This study was conducted to determine physico-chemical characteristics of water and their spatial and temporal fluctuations in the Mazandaran coastal of Caspian Sea in 6 months, four seasons at 4 transects (Tonekabon, Nowshahr, Babolsar, Amirabad) during 2012-2013. 72 samples were collected at surface layer of water in 5, 15 and 30m depths. Then the sampls analyzed based on standard methods. Results showed that the mean of water and air temperature were 19.46±0.85 and 20.25±0.78 ◦C, respectively. Minimum and maximum of water temperature were recorded in winter (7.00) and summer time (28.10). Mean of salinity was 12.35±0.13 ppt. The maximum salinity was recorded in summer and minimum in winter in all transects. Mean of transparency (SD) in the present study was 2.63±0.18m. The mean of pH was observed 8.51±0.02 which was higher than the pervious sampling periods. The mean of DO was observed 6.00±0.07 ml/l during sampling period. Annual concentration of dissolved inorganic nitrogen (DIN= NH4 +, NO2-, NO3-) has a fairly wide variation in diferents months and transects. Percentage of nitrogen components out of DIN were varied 6-53, 0.14-26.0 and 37.0-94.0 respectively. In this study, percentage of DIN was lower than 15% and dissolved organic nitrogen (DON) was higher than 80%. Mean of annual dissolved inorganic phosphorous (DIP) and organic phosphorous were 0.58± 0.04 and 0.48± 0.02 µM, respectively. DIP and DOP percentages recorded 54 and 46 respectively. Mean annual of dissolved silicon (DSi) obtained 9.5± 0.2 µM. Based on the results, the system was in phosphorus limitation during spring and summer but it shifted to nitrogen limitation in autuman and winter. Phytoplankton development was not limited by DSi at any seasons.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Physicochemical parameters ; Nutrients ; Samples ; Temperature ; Salinity ; Transparency ; pH ; Dissolved inorganic nitrogen ; Phytoplankton
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 70pp.
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  • 2
    Publication Date: 2021-05-19
    Description: Persian Gulf waters (areas of Hormuzgan province) in order to determine the best location for installation of Artificial reefs were studied seasonally from December 2006 to March 2007. Distribution of funa and flora and estimation of deposit depth by SCUBA diving method, density and frequency of macrobenthose communities, frequency of ichthyoplankton communities, determination of organic carbon (OC) and Grain size and measurement of water physical factors including salinity, saturation oxygen, dissolved oxygen, temperature, chlorophyll a, in transect and subtransect was studied for recognizing the best placement to installation of artificial reefs. All areas of Shipping, military areas, around of Islands, natural habitats and entrance to jetty were introduced for excluding areas. South of Qeshm Island (transects of Bahman jetty, Bandar Masen and Bandar Salakh) are catching area for small pelagic (sardine and anchovy fishes), therefore in these areas installation of artificial reefs have confined with this restriction. Also entrance to Bahman jetty, sea plant habitats (sea grass and algae) in transects of Bahman jetty and Bandar Masen were considered as restricted areas. In this area, suitable areas for installation of artificial reefs was determined based on distribution of Ichthyoplankton societies for every transect, for macrobenthose enrichment Bahman jetty transect was calculated middle, but transects of Bandar Masen, Hengam island and Bandar Salakh was done good indicator. The deposition depth in transects of Bandar Masen and Hengam island was determined as good factor but this index was known as average factor for transects of Bahman jetty and Bandar Masen. Also, two another indicators, primary production and bottom sturdiness, were calculated as middle factor for Bahman jetty transect, but these indicators were known as good factors for other transects in this area (Bandar Masen, Hengam island and Bandar Salakh). The results of these indicators in transects of Bandar Kong and Bandar Bostaneh in Bandar Lengeh area was indicated that T. O. C and bottom sturdiness indices had no significant difference (p〉0. 05) and the whole of these transects had average priority. Bottom sturdiness, primary productions and macrobenthose communities indices had difference in Bandar Lengeh area (p〈0. 05) and these indices had average priority in Bandar Kong transect and had good priority in transects of Bandar Bostaneh and Bandar Hasineh. Ichthyoplankton community had average priority for Bandar Bostaneh transect, and had good priority for transects of Bandar Kong and Bandar Hasineh. The good priority has obtained for transects of Bandar Charak, Bandar Gorzeh and Bandar Chiroeyah. Also Macrobenthose community, primary production, water physical factors and bottom sturdiness were known as good, good, average and weakness priority respectively for transects of Bandar Charak, Bandar Gorzeh, but primary production, bottom sturdiness, water physical factors and macrobenthose community were resulted as average, good, good and average priority respectively for Bandar Chiroeyah transect . T. O. C index was determined as average priority for transects of Bandar Gorzeh and Bandar Chiroeyah and good priority for Bandar Charak transect. Finally, excluded areas maps, suitability areas maps and feasibility areas maps were drawn by Arc GIS software. In this survey, layers between 10 to 20 meters depth were recognized as the best position for installation of artificial reefs.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Artificial reef ; Macrobenthose communities ; Ichthyoplankton community ; Organic carbon ; Grain size ; Water physiccal indices ; Dissolved oxygen ; Temperature ; Chlorophyll a ; Algae ; Survey ; Ichthyoplankton
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 123pp.
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  • 3
    Publication Date: 2021-05-19
    Description: Following to introduce Vannamei shrimp (Litopenaeus vannamei) into Iran aquaculture industries by fisheries organization its postlarvae were successfully reared in ponds in Bushehr and Choebdeh in Khuzestan. Due to activity of Shrimp site and importance of input and output water quality, this study was done in 11 stations including: two stations in Bahmanshir river, two station in C4 and C5 irrigation canals, six staions in active farms along C4 cannel (Yonesi, Mosavei and Salman Zadeh), and C5 cannel (Mohamadi, Khairi and Ashraf Por) and one staion in output draing were selected. Sampling were carried out from May2009 befor beginning stocking to harvest time in October 2009. Physico- chemical parameters and plankton sampled biweekly and benthic animals and heavy metals were sampled monthly. Some parameters such as pH and temperature by using portable multy parameters and others. Analyzed with standard methods. Heavy metals were measured by plarography method (797 Vamtro). Plankton and benthos samples were studied only in Bahmanshir station. According to results the maximum values for DO (11.1 ppm) PO4 (1.86 ppm) NO3 (8.4 ppm) and TSS (4992 ppm), pH (8.4) NO2 (0.18 ppm) BOD5 (9.06 ppm) were measured. In comparison to aquaculture water quality standards except for TSS in river stations others are located in allowable range. We didn’t observed any main changes in water quality from river to output drainage. The results of biotic parameters in river stations showed that diatoms were the most group of phytoplanktons. Zooplankton groups were Copepods, Rotifera and Protozoa. Tintinids and Nematoda larvae were the most abundant zooplankton. Benthic animals were included nine crustacean species and two annelid species. Isopods with 52% were the most and ant group.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Ecological ; Physico-chemical ; Vannamei shrimp ; Litopenaeus vannamei ; Water quality ; Abadan aquaculture site ; Rearing ; Shrimp ; Ponds ; Sampling ; Plankton ; Heavy metals ; pH ; Temperature ; Benthos ; Phytoplankton ; Zooplankton ; Copepods ; Nematoda larvae
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 80pp.
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  • 4
    Publication Date: 2021-05-19
    Description: The Goal of project implementation was survey of biological roles of Northern pike, Esox lucius, in decreasing of Coarse fish and other un economics organisms in carps ponds and also increasing of final crops in hectare and determination of Suitable ration of pike in ponds. This project implemented by 5 treatment with 3 replicates for every ones in 2 years . The pike density was 200, 350, 500 and 650 fish individuals per hectare for 1 , 2 , 3 and 4 treatment , Respectively, and fifth treatment was without pike. The treatments of 1 and 3 conducted in first year and other in second year of test period. At first, about 26 brooders Caught from Anzali Lagoon, and reproduced by artificial and semi - natural methoods in Sefidroud Pisheries Research Station in 12–14 °c temperature. Produced larvae reared in earthen ponds and fries reached to weight of 10 -12 g after 45 days. Mean weight, length and survival rates of fish was 12.27 and 32.5 g , 11.44 and 15.83 cm , and 40 and 21% after 45 and 60 days , respectively . The carp density in ponds was 3500 fish individualsper hectar and stocking rates were 55 % silver carp, 20 % common carp , 10 % bighead carp and 15 % grass carp . In throughout of the experiment period, physico – chemical factors measured and plankton ( phyto and zoo) , benthos , un wanted fish and other organisms investigated . The biomass of unwanted fishes reduced to 76/81 and 60/6 % in first and second year of experiments respectively. The results showed that Esox lucius had effect in increasing of objective fish produce about 17.9 % and 3.9 % in first and second period of project implementation respectively . The average of fish produce in pond unit ( 2400 m2 )was 842 kg ( 3508 kg/ha ), 825 kg ( 3439 kg/ha ) and 776 kg ( 3232 kg/ha ) in first , second and control treatments first year of test period , and also in second year was 865 kg ( 3603 kg/ha ), 877 kg ( 3652 kg/ha) and 848 kg ( 3531 kg/ha) in second , fourth and control treatments , respectively . A significant different found in final weight mean of common carp between treatments and Control ponds (P 〈0/05), as the weight of common carp in treatments ponds was 220 % in first year and 191 % in second year more than control pond. In end of the trial, the mean weight of Esox lucius was 265 ± 74, 276 ± 104, 159 ± 33 and 265 ± 89 g in 1, 2, 3 and 4 treatment, respectively. Survival rate of Northern pike in 1 to 4 treatment was 43.8, 55.2, 40 and 35.6 %, respectively.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Biological ; Polyculture ; Pike ; Esox lucius ; Carp ; Survey ; Organisms ; Density ; Temperature ; Larvae ; Earthen ponds ; Plankton ; Survival rate
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 132pp.
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  • 5
    Publication Date: 2021-05-19
    Description: Thise studies were conducted seasonaly in 9 sampling period 1n 1991 to assess the physico-chemical parameter status of water of Balikhly chie river (the region after yamchi dam) of Ardabil Provence in relation to its potential for aquaculture development. Water samples were collected by rutner sampler and analyzed for temperature, turbidity, conductivity, total hardness, chloride, COD, CO3 , HCO3,Ca, mg ,TSS ,PO4, NH4 ,NO2 ,NO3, SiO2, DO, SO4 . The water quality showed temporal and spatial variation in this study .The result revealed that the water were slightly alkaline with high total hardness and bicarbonate alkalinity which indicate high buffering capacity to pH changes .the ranged of dissolve oxygen concentration were beetwin7.6 to 13.7 mg/l with mean value of 10.98mg/l which were above the permissible oxygen cocentratio over all study site.the mean water temperature was 17.79 and ranged between 1.6 to 19.6 that is suitable for cold water fish culture while seasonal temperature variation showed that winter is desirable for hatcheries and other seasons for culture practices. Electrical conductivity value ranged between 873 to 1502 with mean of 1135 falls within the limits of suitable salinity ranges for rainbow trout culture. The turbidity and TSS ranged between 20-60FTU and 60168mg/l respectivelyThe levl of TSS concentration were little higer than80 ppm lmits..The values obtained for physicochemical parametersin Balikhly chie river were in conformity with recommended values for fresh water fish farming standared.The fish production potential based on water divertion and oxygen concentration over four study site from yamchi dam to downstream without applying any aeration systems were 38.6,27, 59 and 27 metric tons respectively.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Lak yamchi ; Physic-chemical parameter of water ; Survey ; Sampling ; Turbidity ; Temperature ; Conductivity ; Hardness
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 52pp.
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  • 6
    Publication Date: 2021-05-19
    Description: The aims of this project was to inform and aware about the red tide condition before entering the algal bloomer in water resources to the hatcheries and farmed shrimp complexes in Bushehr province coastal. Field investigation and sampling have been carried out in the southern of the input water channels of Mond, Delvar and Helleh farmed shrimp complexes, which are located along the coastal of Bushehr Province, from April to December 2011 .The physic-chemical parameters such as pH, salinity and water temperature and also meteorological conditions were measured and recorded on the field. The water sampling has been lunched for determination of nutrients and chlorophyll - a, phyto- and zoo- planktons. No Cochlodinium.sp outbreaks have been detected in the studied area, during the study. The only bloom which reported by a fisherman, was outbreak in offshore of Bushehr province in Khoure Khan on 13th September 2011. The sample which transferred to the Iranian National Shrimp Research Institute was included Alexandrium.sp and its density was 2 million cells per liter. The identified phytoplanktons were belonged to three order of Bacillariophyceae (52.6%) with average density of 10778 cells per liter, Dinophyceae (37.7%) with density of 7731 cells per liter and Cyanophyceae (9.7%) with density of 1980 cells. 12 genera belonged to Dinophyceae , 25 genera of Bacillariophyceae and two genera of Cyanophyceae were observed during the study. The highest density of phytoplankton was recorded in Helleh station by 18374 cells per liter. The maximum density of phytoplankton was at Delvar station by 141120 cells per liter in December. The highest density of the phytoplanktons was belonged to Dinophyceae by 126000 by cells per liter of which the Alexandrium.sp had the density of 124500 cells per liter in August 2011. From the Dinophyceae the Alexandrium.sp with mean density of 20345 cells per liter, Ornithocercus 920 cells and Prorocentrum.sp 820 cells were the predominant species. The identified Zooplankton in were belonged to 8 branches and 19 groups. The highest density of zooplankton was recorded in Helleh station by 1194 no. per liter. Nauplii were the dominant zooplankton groups with an average density of 136.4 no. per liter, Tintinnids 98.7, Cyclopoida 60.8, Calanoida 35.7 and Harpacticoids 14.5 no. per liter . The average of water and air temperature was recorded 29.4 °C and 28.3 °C, respectively. Average of salinity was 41.2 and pH was 8.46. The average of depth in all stations was 5.7 m. The mean concentrations of silicate, nitrate, nitrite, ammonia and total phosphate were 1.99, 0.03, 0.009, 0.14 0.15 ppm, respectively and the average of chlorophyll - a was 0.94 mg.m-3.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Physico-chemical ; Cochlodinium.sp ; Shrimp Culture ; Bloom ; Survey ; Hatcheries ; Sampling ; pH ; Salinity ; Temperature ; Chlorophyll a ; Phytoplankton ; Zooplankton ; Alexandrium.sp ; Bacillariophyceae ; Dinophyceae
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 79pp.
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  • 7
    Publication Date: 2021-05-19
    Description: This investigation conducted for evaluation Silo (Cylindrical) Fish Tanks as an applicable method for aquaculture of Rainbow trout (Oncorhynchus mykiss). Current research was designed in two practical phases as accidental experiments through 3 treatments and repeats of which stocked by three Rainbow trout (375 gr) densities as 75, 100 and 125 fish/m3 in 9 silo fish tanks (2 m3). For better understandings of the silo performance method, concrete circular fish tanks (similar volume) considered as controls and stocked as similar fish densities as silo tanks. The duration of the first phase of experiment was 150 days. The second phase of the experiment was determined for evaluating two proposed silo type (Inlet and outlet in bottom side / Inlet from bottom and outlet in upper side). In this stage, proposed silos (stocked by fish of 294 gr weigh) tested for rearing trout for 30 days. Water supplied from two surface wells after some aeration operations. Stocked fish were fed by pellets made by Fish Feed Chineh Company (Ltd) in Iran. Feeding operation conducted according to the recognized manuals by consideration of water temperature, fish weight and biomass. Meanwhile, biometry operation conducted in 10 days intervals while fish were anaesthetized. In addition, water quality was determined by daily measurements. According to the results of the first phase of experiment, there were significant variations on Growth rate, survival rate, FCR, FCE and SGR through the cultured organisms in silo tanks compared to the circular tanks. Meanwhile, according the results of an economic study on this survey, the fish culture in silo tanks showed significant economical and profitable in compare to controls. In additions, the second phase of experiment showed better aeration conditions in silo tanks when inlet water supply from bottom side and outlet located in upper side. Because of the fine distribution of fish in silo tanks and more usage of depth by this method, fish culture would be an applicable and profitable technique in narrow lands and slopes through the mountains area. The maximum stocking rate recorded more than 100 Kg fish/m3 in silo tanks.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Practical ; Silo ; Cylindrical ; Aquaculture ; Rainbow trout ; Oncorhynchus mykiss ; Fish ; Feeding ; Temperature ; Weight ; Biomass ; FCR ; FCE ; SGR ; Culture
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 73pp.
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  • 8
    Publication Date: 2021-05-19
    Description: Mnemiopsis leidyi is one the species of comb-jelly. It belongs to the Ctenophore phylum and lobate order. Mnemiopsis leidyi first appear in the Black Sea in 1980s and reached to the biomass levels up to 1.5-2 kg m2 in the summer of 1989. This species is food rival of pelagic fish. It has been reported that the ctenophore caused the dramatic decrease of zooplankton and pelagic fish stock in the Black Sea. In this study, sampling on Mnemiopsis leidyi, zooplankton and phytoplankton started from July to December 2002 from a total of 2 stations located Anzali and Khazarabad by METU net in the Iranian Coasts of the Caspian Sea. Experimental studies on Mnemiopsis have indicated that Mnemiopsis begins to produce eggs in the Caspian Sea, when it reaches length about 15 mm. Although eggs were obtained even from specimen with 12 mm length and weight of 0.5 g. The most abundant size of reproducing Mnemiopsis was 20-30 mm in the Caspian Sea. Average fecundity of M.leidyi in the Caspian Sea was 1174±741 eggs/day with maximum 2824 eggs/day for specimens with length group of 30-39 mm and the weight about 2.0-2.7 g. Percentage of hatched eggs was not high in experiments with M.leidyi the range from 9 to 92 % after 24 hours. The maximum produce egg of M.leidyi measured with mean 845±733 eggs/day in Salinity of 11 ppt and the minimum egg recorded with mean 2 eggs/day in salinity of 4 ppt. The results showed that the biomass of M.leidyi had some fluctuation in different months and its maximum biomass was recorded in August with a figure of 384±156 g.m2 and the minimum biomass was observed in December with a figure of 87±46 g.m2. The gut contents of Mnemiopsis leidyi showed a wide variety of prey including 84 % of zooplanktons and 16% of Phytoplanktons. The most abundance of intaked foods was Acartia (belong to Copepoda) with 34 % and the least was podon polyphemoides (belongs to Cladocera) with 0.74 %. Also 3.0 % of fish eggs and 4.2 % of Lamllibrachia were found among stomach contents. The young specimen (5〈 mm) consumed more zooplanktons and phytoplanktons comparing to adult ones. Copepoda was dominant zooplankton in the Iranian coasts of the Caspian Sea. Fecundity of Mnemiopsis showed correlation to the length and wet weight in the Caspian Sea and reproduction of M.leidyi was done small size in comparing with other area in the Caspian Sea. Salinity, water temperature and food availability is the most important factor in producing eggs in M.leidyi. It seems, that Mnemiopsis leidyi feeding has been one of the most important factor in declining zooplankton populations and Clupeonella stocks.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Experimental ; Mnemiopsis leidyi ; Diet ; Reproduction ; Species ; Ctenophore ; Phylum ; Biomass ; Pelagic fishes ; Zooplankton ; Phytoplanktons ; Copepoda ; Cladocera ; Salinity ; Temperature ; Comb jellie
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 45pp.
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  • 9
    Publication Date: 2021-05-19
    Description: In 22 August of 2000 an adequate amount of fresh cow manure was transported form Golshahr Cow Farm and deposited in the experiment site. The transported manure was divided equally between five treatments of siloes, depots without plastic coverage, depots with plastic coverage, barrels and tubes. Deposited manures retained in the treatments till 20 May 2001. During the retention time, sampling from three points of cow farm and other treatments carried out with monthly intervals and samples were analyzed for determination -of Ca, Na, NDF. ADF. crude protein, crude fat, moisture; crude fiber, minerals, dry mater and NFE. Temperature, pH and redox potential were measured in situ and all data were analyzed statistically by SAS general linear models. The results showed that month and treatment exert significant effects (P〈0.01, on the variations of the most measured parameters. Depots with plastic coverage had highest mean temperature and then there were depots without plastic coverage, siloes and barrels, respectively. “The temperature increased significantly in the first month of retention but showed some fluctuations in subsequent 4-5 months and then remained relatively constant till the end of experiment period. Depots without plastic coverage showed highest moisture. Optimum moisture value of 40-50 percent obtained for siloes and depots with plastic coverage. Lowest Ca and highest Na values were measured in fresh manure of the cow farm. In two first month of retention time NDF decreased significantly in most treatment but increased subsequently and reached maximum 'percentages during 5-6th month of retention. In first month of retention ADF showed significant decrease in most of treatments but increased in further months and reached to maximum percentage after 4 month retention. In siloes, depots without plastic coverage, and depots with plastic coverage the percentages of protein and fat reduced significantly in the first month of retention, modified during subsequent 6 months and reach valuable percentages. Depots with plastic coverage showed maximum and most suitable protein and fat percentages of about 9 and 2.75 percent after 6 months retention. The percent of crude fiber decreased to minimum level after 3, 5 and l, retention months in siloes, depots without plastic coverage, and depots with plastic coverage and barrels respectively. Values of surface pH in siloes, depots without plastic coverage vice versa of other parameters were minima of 7.1-7.5 at the beginning of retention time that reached to 7.8-8.4 after 4 retention months. The pH of cow farm mostly was more than other treatments. Amount of redox potential in cow farm, siloes, depots without plastic coverage, depots with plastic coverage and barrels fluctuated between -48 to -109, -84 to -12, -62 to -22, -86 to -30 and -65 to -21 millivolt. The minimum levels were at beginning of period and the maximum levels obtained after 4 months of retention in treatment I and 2, after 3 months in treatments 3 and after 5 months in treatment 4. Therefore with care to extent and terns of parameters changes in variation treatments, depots with plastic coverage can introduce the best retention conditions during 4-6 months for decomposition of organic manure for usage in aquaculture.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Fermentation ; organic manure ; Utilization ; Aquaculture ; Fluctuations ; Temperature
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 74pp.
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  • 10
    Publication Date: 2021-05-19
    Description: This project was conducted in five independent experiments in appropriate tanks with suitable aeration and water fellow. Temperature: an experiment designed to evaluate the effect of temperature on growth and survival of tilapia fry by using four thermal regimes consist of 22, 25, 28 and 31 °c in three replicates. Fries with initial wight of .014 g were stocked in plastic container with 10 liter capacity at the rare of 5/liter. Fish were fed on rainbow trout commercial food at a rate of 30 % of biomass 5 times per day. The results showed that some growth indices such as final body weight, daily growth rate, specific growth rate and weight gain increased by increasing water temperature significantly. Although fry survival increased by increasing temperature but these differnces were not significant. the results suggest that in larviculture of Nile tilapia water temperatue should not be less than 28°c. Density: compressibility of Nile tilapia fry was studied by using plastic container with 13 liter capacity. Fry with initial weigh of .034 g were stocked in four treatments 10, 15, 20 and 30 fry/l with four replicates. They fed on rainbow trout food according to their biomass five times per day during the light period. The results showed that some growth indices such as average of final body weight, daily growth rate, specific growth rate and survival decreased by increasing stocking density significantly, while feed conversion rate increased by increasing stocking density. Considering the experiment, it could be suggested that lower stocking density (10/l) resulted the best growth efficiency and survival of Nile tilapia fry. On the other hand, compering the results of growth and survival rate(84%) in two stocking densites(15 and 20/l) showed that it is passible to culture Nile tilapia fry at the stocking density of 20fry/l in suitable condition. Salinity: A study conducted to evaluate the effect of salinity on growth and survival rate of Nile tilapia fry by using six salinity levels (0, 4, 8, 12, 16 and 20 ppt) with three replicates. Fry fed on rainbow trout food five times per day during the light period. Results showed that some growth indices such as average of final body weight, daily growth rate, specific growth rate and survival rate increased by increasing salinity levels up to 8 ppt significantly, and then decreased by increasing salinity levels up to 20 ppt. according to the experiment, it seems that larviculture of Nile tilapia in brackish water is available and the best results achives at 8 ppt. considering the results of growth and survival rate at 16 ppt showed that Salinity up to 16 ppt was tolerable, although reduced the growth and survival of Nile tilapia fry. Photoperiod: the objective of this study was to examine the effects of photoperiod on growth and survival rate of Nile tilapia fry by planning four treatments (6L:18D, 12L:12D, 18L:6D and 24L:0D) and four replicates. Light provided by tow fluorescent lamps those set at a distance of 60 cm above the tanks and worked by an automatic timer. Fry fed on rainbow trout food five times per day. Results showed that average of final body weight, daily growth rate and specific growth rate were loest in 6L:18D and these indices increased by increasing light duration. these differences were not significant among 6L:18D and 12L:12D. but the differences between 6L:18D with 18L:6D and 24L:0D were significant. Evaluation of survival rate showed that photoperiod did not significant effect on survival in all treatments. These finding suggests that a 12L:12D cycle be adequate in case of larval rearing. Cannibalism: An experiment designed to determine the occurrence of cannibalism among 5 different size groups of (5, 10, 20 and 30 g with fry 0.45 g) Nile tilapia population (fry / fingerling) under two stocking densities (1 / 2 and 1 / 4 fingerling / fry) with three replicates in the poly etilen tanks in brackish water condition. Fry were counted at 6, 24, 48, 72, 96, 120 and 144 hours after stocking in two methods (feeding and no feeding). In the feeding trial fingerling were fed on rainbow trout food two times per day. The results showed that cannibalism became more intense as the size difference increased. After passing time cannibalism rate increased. Also results showed increasing fry density causes increasing cannibalism in both treatments (feeding and without feeding). Feeding fingerlings (predator) was effective in reducing cannibalism.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Oreochromis niloticus ; Fry ; Temperature ; Stocking density ; Salinity ; Photo period ; Cannibalism ; Brackish Water ; Growth ; Survival ; Tilapia ; Larvae
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 48pp.
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