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    Changes in blood ion levels and mortality rates in different sized rainbow trout (Oncorhynchus mykiss) following direct transfer to sea water
    (Israeli Journal Of Aquaculture-Bamidgeh, 2004) Türker, A; Ergün, S; Yigit, M
    Plasma ion values and mortality rates were compared for 450 rainbow trout (Oncorhynchus mykiss) of three sizes following direct transfer from fresh water to Black Sea water of about 18 ppt. In fish of 14.29+/-0.30 g, plasma Na+, Cl- and K+ levels significantly (p<0.05) rose above initial values five days after the transfer and peaked at 178.6+/-5.66, 153.9+/-0.14 and 1.14+/-0.04 mM/l, respectively. In 20.45+/-0.48 g fish, these values also rose significantly, reaching 172.4+/-4.24, 151.8+/-6.65 and 0.98+/-0.04 mM/l by day 5. In fish of 29.91+/-0.99 g, however, plasma Na+ and Cl- concentrations peaked 19 days after transfer, reaching only 165.5+/-6.43 and 142.9+/-8.34 mM/l, while plasma K+ reached its highest concentration of 1.02+/-0.06 mM/l on day 12, All three concentrations dropped to near initial values on day 26. In all groups, the plasma Ca2+ level rose significantly (p<0.05) above the initial value five days after transfer and then declined while the plasma P5+ concentration dropped on day 5, reaching a minimum on day 12 and recovering the initial level on day 26. The lowest mortality (8.0+/-1.89%) was recorded in the 30 g group, followed by 19.3+/-0.94% and 24.7+/-0.94% in the 20 g and 14 g groups. The failure of the smallest fish to adapt after direct transfer to sea water was likely due to excessively high plasma Na+ and Cl- concentrations and tissue dehydration, indicating that fish of 30 g best adapt to a seawater environment of 18 ppt.
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    Öğe
    Growth and feed utilization in juvenile black sea turbot (Psetta maeotica) under different photoperiod regimes
    (Tubitak Scientific & Technological Research Council Turkey, 2005) Türker, A; Yigit, M; Ergün, S
    The effects of 4 different experimental photoperiod regimes, LDN (natural photoperiod), LD24:0 (24 h light:0 h dark), LD12:12 (12 h light: 12 h dark) and LDO:24 (0 h light:24 h dark),. on feed intake and growth parameters of juvenile turbot (21 2.3 g) in the Black Sea were determined. Growth was highest in the group exposed to the continuous photoperiod (LD24:0), followed by the LD12:12, LDN and LDO:24 groups in descending order. The lowest growth rate was recorded in the LDO:24 group. According to the results obtained, LD24:0 and LD12:12 photoperiod exposures are best for better growth and food conversion in juvenile turbot.
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    Öğe
    Using ammonia nitrogen excretion rates as an index for evaluating protein quality of prawns in turbot (Psetta maeotica) nutrition
    (Tubitak Scientific & Technological Research Council Turkey, 2005) Yigit, M; Ergün, S; Türker, A; Karaali, B; Bilgin, S
    Total ammonia nitrogen excretion rates were measured in Black Sea turbot (averaging 88.8 g) to compare the protein quality of prawns, the natural food of turbot, with that of the protein source commonly used in the feed industry, i.e. anchovy meal. Two different prawn species (Baltic prawn, Palaemon adspersus, and rockpool prawn, Palaemon elegans) were offered to fish as wet feed at 17.5 +/- 0.5 degrees C and a salinity of 17 ppt. Furthermore, for determination of the effects of wet feed and dry feed on the peak times of ammonia nitrogen excretion rates, another experimental group of fish was offered a commercial dry diet with anchovy meal as a single protein source. The ammonia nitrogen excretion rate in both groups fed prawns peaked 3 h after feeding, while the peak of the excretion rate of fish fed the dry diet was delayed up to 6 h after feeding. Cumulative ammonia nitrogen excretion rates as well as the excretion as a proportion of ingested nitrogen were significantly lower (P < 0.05) in fish fed prawns than those in fish fed the dry diet. Significantly lower excretion levels in the prawn groups might be a reflection of the protein quality of these species, which may be higher than that of the anchovy meal for turbot nutrition.