Effect of hydrogen peroxide solutions on growth of micromycetes Saprolegniaceae on egg membranes of beluga (Huso huso) embryos and on indicators of its embryonic development during incubation

The article describes the data of the experimental works on assessing the influence of hydrogen peroxide so-lutions (0.05, 0.10, 0.20, 0.30, 0.40%) in different concentrations on the growth of the micromycetes Saprolegniaceae on egg membranes of beluga embryos and its embryonic development. In conditions of increasing intensification of aquacultures there is an acute problem regarding to the shortage of approved drugs for treating a common disease in fish farming - saprolegniosis. This disease is caused by species of different genus, the most common of which are the genus Achlya and Saprolegnia belonging to the biological kingdom Chromista (Stramenopila), the Oomycota phylum, the Oomycetes class, the Saprolegniales order, the Saprolegniaceae family. The impact of experimental hydrogen peroxide solutions on the beluga embryonic development and infection with saprolegnial micromycetes was assessed by fish-breeding biological indicators: the number of inseminated oocytes, number of survived embryos and hatched prelarvae, number of embryos infected with the micromycetes Saprolegniaceae and abnormally developing fish. Histological analysis of embryos at different stages of development was also carried out. The experimental works were carried out under production conditions in an incubation apparatus of “Sturgeon” type. The experimental groups were formed in accordance with the experimental solutions’ concentrations. Upon the result of the studies it has been inferred that using a 0.05% hydrogen peroxide solution with a 10-minute-exposure proves effective. This solution sup-pressed growth of micromycetes Saprolegniaceae without any negative impact on the embryonic development. Other experimental solutions had a negative impact on beluga (Huso huso) embryonic development of in most cases, causing the increased mortality and, as a consequence, the increased infection rate.

Comparison of Metabolic Rates of Young of the Year Beluga (Huso huso), Sterlet (Acipenser ruthenus) and Bester Hybrid Reared in a Recirculating Aquaculture System

In the present study, oxygen consumption of two sturgeon species, beluga (Huso huso), sterlet (Acipenser ruthenus), and their hybrid reared in a recirculating aquaculture system were compared over body intervals from 54–107 g to determine the interspecific variation of metabolic rate. Metabolic rates were measured using the intermittent-flow respirometry technique. Standard oxygen consumption rates (SMR, mg O2 h−1) of sterlet were 30% higher compared with beluga and 22% higher compared with bester hybrid. The routine metabolic rate (RMR, mg O2 h−1) averaged 1.58 ± 0.13 times the SMR for A. ruthenus, 1.59 ± 0.3 for H. huso, and 1.42 ± 0.15 for the hybrid bester. However, the study revealed no significant differences (p > 0.05) between mean values of SMR and RMR for beluga and bester hybrid. The scaling coefficient reflected a closed isometry for the hybrid (b = 0.97), while for the purebred species the coefficient of 0.8 suggests a reduction in oxygen consumption with increasing body mass. These findings may contribute to understanding the differences in growth performances and oxygen requirements of the studied species reared in intensive aquaculture system.

Demographics of great sturgeon (Huso huso) in Iranian waters of the Caspian Sea (2008–2010)

Demographic data of the great sturgeon, Huso huso, from the Iranian coastal waters of the Caspian Sea were derived from measurements of individuals with a fork length ranging from 84 to 255 cm, obtained from commercial fisheries. The maximum age of fish caught in the south Caspian Sea was 30 years. The estimates of the asymptotic length L∞ and the growth coefficient (K) were 265.255 cm and 0.062 per year for males and 275.78 cm and 0.08 per year for females, respectively. Total mortality rates obtained by Gulland's method were larger for males (0.64) than for females (0.46). Annual mortality rates were calculated as 47% for males and 37% for females. Data obtained in this study and their comparison with data from previous studies indicate that the great sturgeon stock is definitely exploited in an unsustainable manner.

Genetic Investigation of Four Beluga Sturgeon (Huso huso, L.) Broodstocks for its Reintroduction in the Po River Basin

The reintroduction of the extinct beluga sturgeon (Huso huso L.), an anadromous species with economic and traditional relevance, is a priority in next conservation strategies in Northern Italy. The EU-LIFE NATURA project aims to reintroduce the beluga sturgeon in the Po River basin through a captive breeding program. Critical requirements for the success of the program are river connectivity and knowledge of genetic diversity of the selected broodstocks to ensure self-sustainability of reintroduced populations. Here, the four broodstocks used for the reintroduction of beluga sturgeon have been genetically screened, genotyping 13 loci and sequencing mitochondrial DNA cytochrome b (Cyt b) gene and the entire mitochondrial DNA control region (D-Loop). The four broodstocks showed a medium-high level of nuclear genetic variability and the presence of two sub-populations, evidencing a total level of inbreeding coefficients able to sustain the good potential as future breeders. Mitochondrial analyses showed a genetic variability comparable to wild populations, further strengthening the positive potential of the investigated broodstock. Therefore, this study, showed how the degree of genetic diversity found within the four broodstocks used for H. huso reintroduction in the Po River basin could be suitable to ensure the success of the program, avoiding the inbreeding depression associated with founder effect and captive breeding.