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    Early growth and survival rate of hybrids from male meagre (Argyrosomus regius) × female shi drum (Umbrina cirrosa) compared to their parent species
    (2013) Karahan B.; Gamsiz K.; Gökçek E.Ö.
    Growth performance and survival rates of hybrid meagre × shi drum and purebred offspring of their parents were compared. Hybrids were produced from eggs of hormone-induced shi drum females (Umbrina cirrosa), artificially fertilized by frozen meagre (Argyrosomus regius) sperm. For comparison, purebred offspring were obtained from both species by natural spawning from hormone-manipulated breeders. Growth and survival were observed for 120 days after hatching. The hybrid offspring grew significantly faster than the purebred. On day 120, the mean weights were 12±1 g for the meagre, 5±0.5 g for the shi drum, and 22±1 g for the hybrid juveniles. The mean daily growth coefficients were 1.9 for the meagre, 1.3 for the shi drum, and 2.1 for the hybrids. Estimations of growth heterosis, the extent to which the hybrids outperformed their parent species, showed high hybrid vigor: heterosis for mean weight was 159% and for daily growth coefficient was 31%. The hybrids also had better survival rates than either of the purebred juvenile populations: 49±0.03% for the meagre, 34±0.02% for the shi drum, and 78±0.02% for the hybrids. Therefore, heterosis for survival rate was 86%. According to the growth performance and survival rate, crossing of these two species is strongly suggested.
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    The effect of dietary lipid on the growth performance of Meagre (Argyrosomus regius Asso, 1801)
    (Israeli Journal of Aquaculture - Bamidgeh, 2016) Korkut A.Y.; Sert S.C.; Kop A.; Gamsız K.; Karahan B.
    The aim of the study was to investigate the effects of dietary lipid on the growth and feed utilization of Meagre (Argyrosomus regius Asso, 1801), taking into account their feeding behavior of collecting food from the bottom of the cages. The fish (141.07±0.5g, average weight ± SD; 22.18±0.53 cm, average total length± SD) were fed three isonitrogenous experimental diets (45% crude protein, dry matter) containing 16% (group A), 18% (group B), and 20% (group C) crude lipids for 570 days. The fish were stocked into 9 net cages (16 m diameter; 7 m deep) at a density of 16000 fish per cage with 2 replications. At the end of the experiment fish in the A, B, and C groups reached 1054.59±5.9, 1026.32±4.3, 955.31±2.3 mean live weight (g) and 45.78±1.6, 44.43±1.4, 43.88±1.4 mean total length (cm) respectively. FCR and CF values were 1.99, 2.07, 2.14 and 1.999, 1.131, 1.170 respectively for each group, at the end of the study. VSI, HIS, and GSI values were also calculated. Growth rate in fish from group A (fed the lowest lipid diet) was superior to the other dietary groups. Cross sections of their liver were checked and were found to have less lipidosis. © 2016, Israeli Journal of Aquaculture - Bamidgeh. All rights reserved.
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    Microsatellite polymorphism of seabass (Dicentrarchus labrax) breeders: Natural and cultured stocks
    (Parlar Scientific Publications, 2014) Karahan B.; Gökçek E.Ö.; Gamsiz K.; Magoulas A.
    Polymorphism of 12 microsatellite markers was analyzed to investigate genetic variability and structure in broodstock populations of the Mediterranean sea bass Dicentrarchus labrax. Two broodstocks of wild origin (AN, EN) that had been collected from the different locations of the Aegean Sea, as well as one of culture origin (after three generations in captivity) (AF) were used in the analysis. In total, 319 individuals from these three sample groups were scored. The average allele numbers of the 12 microsatellite loci were 9.16, 8.9, and 11.5 for AF, AN and EN groups, respectively. Wild groups showed a higher variation than the cultured strains, and significant deviations from Hardy-Weinberg Equilibrium were observed. The observed heterozigosity values for AF, AN and EN groups were 0.502, 0.608 and 0.620, respectively. The significant linkage equilibrium was found for all groups between various loci. Furthermore, AMOVA results confirmed a significant genetic differentiation between all populations with an estimated FST value of 0.113 (P<.001), in accordance with the pair-wise estimates between groups. The results showed that genetic variability was the lowest for the culture-originating broodstock population, possibly due to the inbreeding effect. Bayesian analysis showed that individuals in populations represented 5 genetic groups (K=5). However, two wild broodstock populations also showed a low genetic variability, indicating the importance of collecting fish from different geographic locations while establishing any broodstock population in a hatchery.