Species and hybrid identification of sturgeon caviar: a new molecular approach to detect illegal trade.

Overexploitation of wild populations due to the high economic value of caviar has driven sturgeons to near extinction. The high prices commanded by caviar on world markets have made it a magnet for illegal and fraudulent caviar trade, often involving low-value farmed caviar being sold as top-quality caviar. We present a new molecular approach for the identification of pure sturgeon species and hybrids that are among the most commercialized species in Europe and North America. Our test is based on the discovery of species-specific single nucleotide polymorphisms (SNPs) in the ribosomal protein S7, supplemented with the Vimentin gene and the mitochondrial D-loop. Test validations performed in 702 specimens of target and nontarget sturgeon species demonstrated a 100% identification success for Acipenser naccarii, A. fulvescens, A. stellatus, A. sinensis and A. transmontanus. In addition to species identification, our approach allows the identification of Bester and AL hybrids, two of the most economically important hybrids in the world, with 80% and 100% success, respectively. Moreover, the approach has the potential to identify many other existing sturgeon hybrids. The development of a standardized sturgeon identification tool will directly benefit trade law enforcement, providing the tools to monitor and regulate the legal trade of caviar and protect sturgeon stocks from illicit producers and traders, hence contributing to safeguarding this group of heavily threatened species.

Molecular genetic analysis among subspecies of two Eurasian sturgeon species, Acipenser baerii and A. stellatus.

Two species, the Siberian sturgeon, Acipenser baerii, and stellate sturgeon, A. stellatus, were studied using mitochondrial DNA (mtDNA) (D-loop, cytochrome b (cyt-b) and ND5/6 genes) sequencing to determine whether traditionally defined subspecies correspond to taxonomic entities and conservation management units. Initially, several mtDNA regions for each taxon (A. baerii: 737 bp D-loop, 750 bp ND5, 200 bp ND6, and 790 bp cyt-b; A. stellatus: 737 bp D-loop and 600 bp ND5) were examined. The D-loop was the most variable region and was sequenced for 35 A. baerii and 82 A. stellatus individuals. No fixed, diagnostic differences were found between any of the subspecies. Geographical structuring of haplotypes was observed within A. baerii, and gene flow estimates suggest isolation of the A. baerii baicalensis subspecies and the Yenisie and Lena River populations. No intraspecific subdivisioning was found within the genetic data for A. stellatus. The use of the phylogenetic criterion (fixed diagnostic differences) for identifying conservation units is compared to the rationale and results of other methods. Overall, morphologically and geographically based subspecies designations within Acipenseridae may not directly correspond to the biological entities appropriate for management and should not be used for conservation programmes without genetic support.