Sturgeon fish (Acipenseriformes) is commercially used to produce high quality fish meat and highly priced caviar. In fact, all species of Sturgeon fish are integrated into CITES appendix. Sturgeon (Acipenser baerii) is the most frequently bred/reared and the most commercial representative of its kind, not only in Europe but also in Asia. The aim of this final project is to evaluate international sturgeon trade while using CITES references from 1998-2012. The source of data(s) was commercial database CITES. Over the last 15 years, we have exported and imported almost 5000 tons and 32 million pieces of all species. During this monitored period the frequency/traffic of the trade increased. The mostly traded forms were fish eggs which were exclusively destined/designated for commercial purpose and came from those specimens which were reared in captivity - (94% from commercial activity). People mostly traded sturgeon in these forms : (1) eggs, (2) caviar, (3) extracts,(4) derivatives, (5) fish meat and others. In the last 3 years, the trade intensity in fish eggs markedly decreased. On the contrary, since 2008 there was an annual growth of/in the sale of caviar. France was not only the country of origin but also the country where there was the largest/greatest/biggest volume of market. Germany was one of the main export countries, while Armenia , if we take the quantity (kg) into account. On the other hand, The U.S. was the main import country. Sturgeon was exported in the greatest quantity to Moldavia. During the period of time mentioned above, The Czech Republic exported only twice (35 000 pieces) and imported (210 pieces) of living specimen.

Both Elasmobranchii and Acipenseriformes have a spiral intestine, developed by the intestine folding inward and twisting upon itself. A comparative analysis of the digestive system of examples of Subclass Elasmobranchii (sharks and rays) to Order Acipenseriformes (sturgeon and paddlefish) was conducted through gross dissection and scanning electron microscopy (SEM) analysis. Urobatis jamaicensis, Acipenser baerii, and Polyodon spathula were used due to accessibility. Gross dissection analysis yielded that the acipenserids have a columnar spiral valve with 8 infoldings, and U. jamaicensis has a posterior spiral valve with 13 infoldings. SEM analysis showed angiogenesis, where visible, occurred inversely with age in all species. More venous vessels were present than arterial vessels in the outer layers of the intestine, the muscularis and serosa, while the majority of the arterioles were found in the mucosa and submucosa. The vascularization pattern of the spiral valve in U. jamaicensis showed a diamond branching pattern on the surface anteriorly and posteriorly with a lateral drainage system at the midsection. Only the lateral drainage system was found in A. baerii and P. spathula. The daughter arterioles and venules to the intraintestinal artery and intraintestinal vein coincided with the turns present in the spiral valve of each species. This study suggests A. baerii and P. spathula are sister taxa and do not share a direct common ancestor with U. jamaicensis based on similarities and differences between the spiral valve vasculature.

Sturgeon species (order Acipenseriformes) are prone for interspecific hybridization. Anthropogenic activities in river basins influence sturgeon reproduction by destruction of their natural spawning grounds. Consequently, spawning areas, as well as the time of spawning of sturgeon species overlap and different sturgeon species reproduce concurrently. This increases the probability of meeting of heterospecific gametes and pre-zygotic postcopulatory reproductive barriers, comprising of sperm competition and cryptic female choice, may play an important role in preventing undesirable interspecific hybridization. The goal of this study was to evaluate the role of interspecific sperm competition and cryptic female choice during interspecific hybridization of sterlet (Acipenser ruthenus) and Siberian sturgeon (Acipenser baerii). Reproductive characteristics (fertilization rate and hatching rate) were described in each of experimental and control groups showing similar values for competitive and non-competitive trials. Parentage assignment was performed in hatched larvae using combination of mitochondrial DNA and microsatellite DNA markers. Obtained results revealed higher fertilization success of sterlet spermatozoa, when these competed for fertilization with spermatozoa of Siberian sturgeon. Total reproductive success of starlet spermatozoa was 78.9 % and Siberian sturgeon 21.1 %. Contrary, when spermatozoa did not compete for fertilization, males of analysed species showed equal fertilization success. In the trials, where eggs of both studied species were mixed and fertilized by sperm from each species separately, eggs of any species did not show a tendency to bias fertilization by spermatozoa of conspecific males. Probably, there are no pre-zygotic postcopulatory reproductive barriers that prevent interspecific hybridization of sterlet and Siberian sturgeon at the gametic level.