Devrim Memiş

Genetic variability and differentiation of wild and cultured tench populations inferred from microsatellite loci

Nine species-specific microsatellites were used to characterize 792 tench, Tinca tinca (L.), from 21 wild and cultured populations. Seven loci were polymorphic expressing four to 22 alleles. A Spanish cultured strain was homozygous at all loci for all individuals studied. Low variability was also observed in a wild population from Sapanca Lake, Turkey and a Chinese cultured strain. In contrast, the highest variabilities were found in wild tench from lake Felchowsee (average number of alleles), and the cultured strain from Königswartha (average heterozygosity), both from Germany. Genetic differentiation between populations was moderate to high. The smallest genetic distances were found between the geographically most distant populations. A Neighbor-Joining tree showed only two major clades consisting of 4 and 17 populations, respectively. Within the smaller clade the Turkish wild and Spanish and Chinese cultured tench formed a sub-cluster with 100% bootstrap support. Possible reasons for the latter unexpected grouping are discussed.

Determination of sex and gonad maturity in sturgeon (Acipenser gueldenstaedtii) using ultrasound technique

ABSTRACT This study was conducted to investigate the sex and gonad stage of Russian sturgeons (Acipenser gueldenstaedtii) under natural water conditions in concrete ponds through the use of ultrasound technique. The ultrasound technique was effective in determining sturgeon gender. However, because the ultrasound showed that males were ready to produce viable sperm but females were not ready to produce eggs in autumn, it is clear that another ultrasound examination would be needed during the breeding season to identify females with mature eggs to ensure fertilization success.