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    A Comparison of Ageing Techniques to Improve Precision of Age Estimation from Fish Scales
    (Ege Univ, Fac Fisheries, 2005) Gursoy, Cigdem; Tarkan, Ali Serhan; Gaygusuz, Ozcan; Acipinar, Hasan
    Scales of rudd, Scardinius erythrophthalmus (L, 1758), prussian carp, Carassius gibelio ( Bloch, 1782) and roach, Rutilus rutilus (L., 1758) were sampled from two different habitats. Two methods of determining age from scales of fish were applied for all fish species. There was disagreement between methods. The agreement between the determinations of different age readers was better with the impressing scale method than cleaning scale method. Impressing method produced the best results in terms of precision of the age estimates besides it had many advantages such as quick - apply, storing data and easy back-calculation.
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    Öğe
    Interannual variability of fecundity and egg size of an invasive cyprinid, Carassius gibelio
    (Taylor & Francis Inc, 2007) Tarkan, Ahmet Nuri; Gaygusuz, Ozcan; Tarkan, Ali Serhan; Gursoy, Cigdem; Acipinar, Hasan
    A population of the invasive Prussian carp (Carassius gibelio) was examined over a three-year period in a mesotrophic reservoir to find out interannual variations of fecundity and egg size and the influence of maternal condition (total length, TL, and age class) and environmental factors (water temperature and fish density) on these variables. Prussian carp reproduction was synchronous, with only a single batch, and fecundity ranged from 1,250 to 62,400 eggs per female. Relative fecundities and egg size showed no significant between-year differences. Fecundity increased with age, whereas egg diameter remained unchanged with age and TL. Fecundity was affected positively by TL and negatively by fish density, whereas temperature had no significant effect. Egg size was not affected by fish density or temperature.
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    Population Genetic Structure of Petroleuciscus borysthenicus (Kessler 1859) in Northwestern Türkiye Using Mitochondrial COX1 Gene
    (Wiley, 2024) Agdamar, Sevan; Sac, Gulsah; Acar, Umit; Gaygusuz, Ozcan; Dogac, Ersin; Ozulug, Mufit
    Petroleuciscus borysthenicus is a species with a wide distribution from the eastern, western, and northern Black Sea and Azov Sea basins, the Aegean Sea basin, and Northwestern T & uuml;rkiye. However, there has been relatively little attention on the genetic variability of this species in their native distribution range, and nearly no study has been conducted in T & uuml;rkiye despite its importance in biodiversity. The aim of this study was to elucidate the genetic variability and population structure of P. borysthenicus from Northwestern T & uuml;rkiye using an integrated molecular method. A total of 72 specimens were collected from 13 localities in the Northwestern part of T & uuml;rkiye. A total of six haplotypes were identified in all specimens. A relatively low level of genetic variability was found for P. borysthenicus throughout the study region based on the indices of genetic diversity including haplotype diversity and nucleotide diversity for the cytochrome oxidase subunit I (h = 0.507, pi = 0.0027). The pairwise FST values between the samples ranged from -0.123 to 1.000. Furthermore, our results revealed no provable recent demographic expansion for P. borysthenicus from Northwestern T & uuml;rkiye. However, more studies using additional geographic sampling and molecular analysis are needed to enhance our knowledge of the diversity and distribution of this species.