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Ninety-five microsatellite loci were isolated from the output of two Next Generation Sequencing projects: a genomic Illumina RADSeq and a transcriptomic Roche 454 cDNA sequencing of the Adriatic sturgeon (Acipenser naccarii). From a total of 7697 loci identified, 72 were characterized and 57 were polymorphic in the tetraploid A. naccarii, providing new markers suitable for parental allocations to be performed for future conservation actions. Loci isolated from the transcriptome showed a higher level of polymorphism, which could be related to the different sequencing approaches used. Notably, a higher rate of duplication was observed in the transcribed loci, pointing to a preferential retention of sequences with a functional role after whole genome duplications occurred in sturgeons. Cross-species amplification of these markers was also assessed in the diploid beluga sturgeon (Huso huso), with the aim of setting up a panel of markers to be applied in future conservation programmes regarding this species.

Summary The Adriatic sturgeon (Acipenser naccarii Bonaparte, 1836), endemic to the North Adriatic region, was recently reclassified by IUCN as ‘Critically endangered and possibly extinct in the wild’ since no natural spawning has been recorded in the last 20 years. Its survival relies on restocking activities originating from a single captive broodstock collected by a private aquaculture plant (V.I.P.) in the 1970s and is currently reduced to 13 individuals. Few alternative brood-stocks of F1 animals have been retained for use in the near future. Thus far, brood-stocks, as well as all stocks released in the wild, have been randomly chosen without regard to their genetic composition. The consequence of breeding programmes with no genetic input was evaluated in the Ticino River Park (TRP) in Italy. A parental allocation procedure based on microsatellite markers useful for tetraploids was used following a Band-Sharing approach. Levels of relatedness within the TRP F1 captive breeders (Stock_1) and among animals released by TRP in the past (Stock_2) were explored and compared with the stock of wild origin. The pronounced decrease in genetic diversity observed in the analysed sample suggests the need for complete reorganization and coordination of conservation efforts for this species, paying particular attention to the long-term preservation of the genetic diversity. Also identified is the only potentially suitable stock of F1 animals that should be used as source of future breeders.

Summary The parental allocation (PA) in aquaculture allows the association between progeny and broodstock stocks even if the different families of offspring are reared in the same tank. Fingerprinting is needed for PA, and microsatellites are the codominant and polymorphic markers mainly used for this purpose. The simplest method of PA is the exclusion approach, based on the Mendelian mode of inheritance. The rejection of a parent-offspring hypothesis is based on incompatibility between DNA-profiling of offspring and parents. When the exclusion method is not possible a likelihood approach can be used, therefore the progeny is assigned to parents which are not excluded using the likelihood scores derived from their genotypes. Parentage is ambiguous when more parents present the highest non zero likelihood. The software for PA is disposable for diploids, but not for polyploids like sturgeons, in particular Acipenser naccarii which is a functional tetraploid species. To solve the problems concerning to the PA in tetraploids a Windows-based software was developed, using the exclusion method and likelihood approach in the case of multiple allocations. A simulation computer-procedure was also developed to validate the software algorithms. The total results obtained were: correct allocations 93.7%; ambiguous allocations 2.1% and erroneous allocations 4.2%.