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Turbot, Scophthalmus maximus, is a commercially important demersal flatfish species distributed throughout the Black Sea. Several studies performed locally with a limited number of specimens using both mitochondrial DNA (mtDNA) and microsatellite markers evidenced notable genetic variation among populations. However, comprehensive population genetic studies are required to help management of the species in the Black Sea. In the present study eight microsatellite loci were used to resolve the population structure of 414 turbot samples collected from 12 sites across the Black Sea. Moreover, two mtDNA genes, COI and Cyt-b, were used for taxonomic identification. Microsatellite markers of Smax-04 and B12-I GT14 were excluded from analysis due to scoring issues. Data analysis was performed with the remaining six loci. Loci were highly polymorphic (average of 17.8 alleles per locus), indicating high genetic variability. Locus 3/20CA17, with high null allele frequency (>30%), significantly deviated from HW equilibrium. Pairwise comparison of the F ST index showed significant differences between most of the surveyed sampling sites (P < 0.01). Cluster analysis evidenced the presence of three genetic groups among sampling sites. Significant genetic differentiation between Northern (Sea of Azov and Crimea) and Southern (Turkish Black Sea Coast) Black Sea sampling sites were detected. The Mantel test supported an isolation by distance model of population structure. These findings are vital for long-term sustainable management of the species and development of conservation programs. Moreover, generated mtDNA sequences would be useful for the establishment of a database for S. maximus.

Summary The aim of this report is to provide an overview of the current status of efforts on the potential rehabilitation of sturgeon populations in Turkish waters, describing the structure and the outcome of projects carried out since 2006 and identifying the strategic needs for sturgeon conservation measures at a national level. It is well known that there were six sturgeon species occurring around Turkish Black Sea coasts while entering the rivers, mainly Kızılırmak, Yeşilırmak, Sakarya and Çoruh Rivers for spawning. Anadromous sturgeon species have been strictly protected throughout Turkey since 1997. Conservation and management measurements have been implemented since 1970s. However, this was apparently with little success as stocks continued to decline and habitats deteriorated further, threatening the stocks with extinction. At the same time the needs for survival are not well documented. A project was initiated on 30 January 2006, consisting of seven‐work packages including studies on population structure, reproduction, habitat assessment, genetic variability between and within stocks and the development of protective management strategies and plans. The work covered the Turkish Black Sea coastline and the rovers Yeşilırmak, Kızılırmak, Çoruh and Sakarya. Actively sampled and/or accidentally caught specimens have been tagged by T‐bars and released after measurements and tissue sampling for genetic analyses. In addition, broodstocks of Russian sturgeon (Acipenser gueldenstaedtii), Beluga (Huso huso), and stellate (A. stellatus) are being built by rearing fish at the Central Fisheries Research (Yomra, Trabzon, Turkey) Institute. Reproduction studies have mainly focused on sperm collection, cryopreservation and induced spawning as well as on larval rearing.

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The Russian sturgeon, Acipenser gueldenstaedtii, is a critically endangered fish species. Hatcheries are operated in several countries within its natural range to produce stocking material for release into the wild and also for aquaculture purposes (caviar and meat production). An appropriate genetic broodstock management (plan or strategy) is required to avoid negative effects, e.g., admixture and hybridization of genetically differing stocks or loss of genetic variability due to inbreeding and genetic drift. Therefore, 11 tetrasomic microsatellite loci were newly isolated from the Russian sturgeon genome and arranged together with an already known locus into four multiplex PCR sets. These microsatellites were used to characterize three groups of hatchery juveniles from Germany (aquaculture production), Turkey, and Romania (production of stocking material) as well as a group of wild-caught adults from the Danube River, Romania. Based on the variability within groups, measured by the mean number of alleles per locus and expected heterozygosity, and the differentiation between groups, measured by Nei's G ST and genetic distance D, the ability of the 12 loci to detect unwanted reductions in genetic variability within hatchery juveniles and to differentiate between groups could be demonstrated. This set of loci can also be used to identify those pairs of spawners that transmit the highest possible genetic variability to the next generation.