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    Effect of dietary olive pomace oil and L-carnitine on growth and chemical composition of African catfish, Clarias gariepinus (Burchell, 1822)
    (Israeli Journal Of Aquaculture-Bamidgeh, 2004) Yilmaz, E; Naz, M; Akyurt, I
    The effects of dietary olive pomace oil and L-carnitine on growth performance, body indices and chemical composition of African catfish, Clarias gariepinus, were investigated. A 3x2 factorial design was used by offering diets having three different energy/protein ratios and supplemental L-carnitine at either 0 or 2000 mg/kg diet. Ten juvenile African catfish (12 g/fish) were stocked into 80-I glass aquaria and fed an experimental diet for seven weeks. The L-carnitine supplementation did not affect body indices. However, growth and chemical composition were influenced by both dietary lipid and L-carnitine. The increase in muscle lipid was greater than in the liver for all treatments. Fish fed the high energy diet (9% olive pomace oil) had a low appetite and feed intake, while fish fed the low energy diet (3% olive pomace oil) and supplemental L-carnitine had better feed intake and growth. On the other hand, fish fed the high energy diet (9% olive pomace oil) with or without L-carnitine had better feed conversion.
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    The effect of varying dietary energy on growth and feeding behaviour of common carp, Cyprinus carpio, under experimental conditions
    (Elsevier, 2005) Yilmaz, E; Sahin, A; Duru, M; Akyurt, I
    In this study, it was aimed to determine the effects of five isonitrogenous (35% CP) diets I, II, III, IV and V, having respective energy contents 10.85,11.82,12.73,13.69 and 15.06 MJ DE kg(-1) on feeding behaviour and growth of common carp with relation to each other. These energetic diets were made by additions of different amount of soy-acid oil with equalizing dietary protein content. Experimental fishes were grouped as Group I, II, III, IV and V. Each group of fish was fed on their respective diet (Group I was fed diet I). Diets were offered to fishes twice a day as two meals at 9:00 a.m. and 17:00 p.m. for 60 days. Behavioural observations were recorded twice a week at 10 min intervals for I h period. Fish that had the lowest energetic diet showed the best growth and feed conversion ratio compared to those fed with higher energetic diets (P < 0.05). In addition, fishes that had the lowest energetic diet were more active than the others with respect to total (swimming + foraging + grouping + attention to servicer) activity (P < 0.01). The present results suggested that soy-acid oil should not be used in common carp diet to increase its energy content. Experimental fishes were more active in the mornings than evenings (P < 0.01), showing the common carp is a typical diurnal eater. In conclusion, the current results showed that high energetic diets decreased the appetite of fish, as evidenced the reduction in growth, feed intake, foraging activity and attention to the servicer. (c) 2004 Elsevier B.V. All rights reserved.
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    Effects of androstenedione, a phytoandrogen, on growth and body composition in the African catfish Clarias gariepinus
    (Lab Research Fish Diseases, 2005) Turan, F; Akyurt, I
    The present study investigated the effects of a phytoandrogen, androstenedione, on growth, body composition, and survival in African catfish, Clarias gariepinus. Three concentrations (25, 50, and 75 mg/kg feed) were administered for 120 days. Survival of treated groups did not significantly differ from the control and ranged 94.44-97.78%. A significantly higher weight gain was obtained in the 50 and 75 mg/kg diets. The fish fed these diets also had significantly better food conversion and protein efficiency ratios. Apparent net protein utilization was better in treated groups than in the control. The protein and lipid contents of the carcass of treated fish were significantly higher than in the control, with the highest contents in the 50 mg/kg treatment. The highest ash content was in the 25 mg/kg treatment. In overall parameters, 50 mg androstenedione per kg diet was the optimal concentration.
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    Effects of dietary fish oil, soy-acid oil, and yellow grease on growth and hepatic lipidosis of hybrid tilapia fry
    (Society Of Israeli Aquaculture & Marine Biotechnology, 2005) Genc, E; Yilmaz, E; Akyurt, I
    The objective of this study was to compare the effects of dietary lipids on growth and liver histopathology of hybrid tilapia, Oreochromis niloticus x O. aureus, fry (6.0 g). Fish were fed one of six diets containing 8.4% fish oil (control), 8.4% soy-acid oil, 8.4% yellow grease, 5.6% yellow grease plus 2.8% soy-acid oil, 2.8% yellow grease plus 4.6% soy-acid oil, or 4.2% soy-acid oil plus 4.2% yellow grease for 60 days. Growth was similar in all groups and retarded in comparison to earlier studies. Lipid accumulation as well as microvesicular (foamy degeneration) and macrovesicular degeneration in the liver were histopathologically detected.
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    Growth of the catfish Clarias gariepinus (Clariidae) in the River Asi (Orontes), turkey
    (Soc Francaise D Ichtyologie, 2002) Yalçin, S; Solak, K; Akyurt, I
    Vertebrae from 720 Clarias gariepinus from the River Asi were used for the study of age and growth. The population consisted of 0+ - 5 age groups including females to 48.75% in addition to males to 50.83% and the abnormal (intersex) of 0.42%. According to the Von Bertalanffy growth model, length equations obtained for females and males were L-t = 82.94 [1 - e(-0.15(t + 1.72))] and L-t = 85.32 [1 - e(-0.1444(t + 0.69))]respectively. The Von Bertalanffy equations did not fit the data satisfactorily, because there were not enough old fish in the data. The absolute length increments for the major age groups (0-3) were 5.32 cm, 9.74 cm, 8.22 cm and 5.68 cm, 10.11 cm, 8.63 cm for females and males respectively. The weight increments for the major age groups (0-3) for females and males were 48.07 g, 179.41 g, 245.51 g and 50.31 g, 167.19 g, 195.02 g respectively. The relationships between the total length in cm (L) and the weight in g (W) for the female and the male were calculated to be W = 0.010 L-2.90 and W = 0.016 L-2.74 respectively. The condition value of C. gariepinus population was found to be high at young ages (0+ and 1) whereupon the increase to 0.8 was replaced by decline in the River Asi. The monthly fluctuation of the condition of catfish is more related with temperature and feeding. It is observed that C. gariepinus population in the River Asi that have a commercial value is under some stress factor such as lack of water, excessive fishing and pollution.
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    Heavy metals in three commercially valuable fish species from Iskenderun Bay, Northern East Mediterranean Sea, Turkey
    (Elsevier Sci Ltd, 2005) Türkmen, A; Türkmen, M; Tepe, Y; Akyurt, I
    Concentrations of cadmium, iron, lead, zinc, copper, manganese, nickel, chromium, cobalt and aluminum were determined in three commercially valuable fish species, Saurida undosquamis, Sparus aurata, Mullus barbatus, from iskenderun Bay in August 2003. The concentration of metals was measured by atomic absorption spectrophotometry (AAS). Concentrations of the heavy metals in examined fish species ranged as follows: Cd 0.01-4.16; Fe 0.82-27.35; Pb 0.09-6.95; Zn 0.60-11.57; Cu 0.04-5.43; Mn 0.05-4.64; Ni 0.11-12.88; Cr 0.07-6.46; Co 0.03-5.61; Al 0.02-5.41 mg kg(-1) dry weight, respectively. The concentration of metals was significantly affected by the sampling site and fish species. Heavy metals in the edible parts of the investigated fish were in the permissible safety levels for human uses. (C) 2004 Elsevier Ltd. All rights reserved.
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    Morphometric comparisons of African catfish, Clarias gariepinus, populations in Turkey
    (Inst Vertebrate Biology As Cr, 2005) Turan, C; Yalçin, S; Turan, F; Okur, E; Akyurt, I
    The pattern of morphometric differentiation among six populations of Clarias gariepinus sited in the Asi, Seyhan, Ceyhan, Goksu, Aksu, and Sakarya river systems in Turkey was examined. Univariate analysis of variance revealed significant differences between means of the six samples for 18 out of 20 standardized morphometric measurements. The first canonical function accounted for 39 % and the second for 29 % of between-group variability. In principal component analysis, the first component accounted for 20 % and the second for 12 % of the shape variations among the samples. Plotting the first and second principal components showed that the observed differences were mainly from measurements taken from the head of fish, indicating this region to be important in the description of population characteristics. Visual examination of the samples along the canonical functions revealed a clear between-sample differentiation. All the samples except the Seyhan and Aksu samples were clearly distinct from each other. Sakarya and Goksu samples were mostly isolated from each other and from all other samples. The overall random assignment of individuals into their original groups was high (78%). The proportion of correctly classified individuals into their original group was highest in the Sakarya sample (93%) and high in the Goksu (89 %) and the Ceyhan (86 %) samples, indicating that these samples are highly divergent from each other.
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    Protective effect of clinoptilolite on lead toxicity in common carp Cyprinus carpio
    (Parlar Scientific Publications (P S P), 2004) Tepe, Y; Akyurt, I; Ciminli, C; Mutlu, E; Çaliskan, M
    Protective effects of clinoptilolite, a natural zeolite, on lead toxicity in common carp Cyprinus carpio were investigated. Sublethal concentrations of lead nitrate (60 mg/L) in water for a 35-day period decreased both the soluble protein and RNA contents in the liver of the common carps and also caused significant changes of some biochemical parameters. The treatment of exposure water with clinoptilolite (50 mg/L) decreased lead accumulation in fish. No adverse effects of clinoptilolite application were observed.
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    Reproduction tactics, age and growth of Capoeta capoeta umbla Heckel 1843 from the Askale Region of the Karasu River, Turkey
    (Elsevier, 2002) Türkmen, M; Erdogan, O; Yildirim, A; Akyurt, I
    The age, growth and reproduction are described for C c. umbla from the A kale Region of Karasu River from November 1995 to October 1997. Fish aged 1-12 years were present in the samples. The overall male to female ratio was 1.3:1.0. Growth in length was expressed for both sexes with the von Bertalanffy equations. Growth parameters were estimated as L-infinity = 42.3 cm, k = 0. 1457, t(0) = -0.98 for males: L-infinity 45.7 cm, k = 0. 1393, t(0) = -0.83 for females. The length-weight relationships were described for males (a = 0.0139, b = 2.936) and for females (a = 0.0117, b = 2.991). Fecundity ranged from 3754 to 35 859 ova per female for C c. umbla ranging from 21.0 to 40.2 cm fork length. Spawning period was between May and July, and males (16.9 cm) reached first maturity at smaller lengths than females (20.9 cm). (C) 2002 Elsevier Science B.V. All rights reserved.