Population genetic structure of Persian sturgeon (Acipenser persicus) between South Caspian Sea and Sefidrud River using DNA sequencing method

The goal of this study was to analyse the population genetic structure of the Persian sturgeon (Acipenser persicus) between South Caspian Sea and Sefidrud River with mtDNA control region (Dloop gene) and DNA sequencing method during 2010 – 2012 sturgeon stock assessment project. Fish speciemns were collected by bottom trawl net. Extraction of DNA, PCR and DNA sequencing were carried out. Diversity index, the gamma distribution shape parameter for the rate heterogeneity among sites and nucleotide sequence, Fst index, exact test, the historical demographic pattern using neutrality tests and mismatch distribution analysis (D test of Tajima and Fs test of Fu) were analysed. Thirteen haplotypes were obtained, average (±SD) for haplotype diversity was 0.961 ± 0.101, nucleotide diversity was 0.038 ± 0.015, the gamma distribution shape parameter was 0.19, Fst index revealed little genetic structure between populations and the significant Fst value was seen by 10000 permutation only between Sefidrud River and Other Areas (P≤ 0.05) and was confirmed by exact test of population differentiation. Mismatch distribution for Acipenser persicus appeared to be unimodal, which closely matched the expected distributions under the sudden expansion model and supported by the low Harpending’s Raggedness index (0.061). Tajima’s D and Fu’s Fs statistics were -0.84 and - 0.220, respectively, and was not significant. The results of this study showed that the population of Acipenser persicus in Sefidrud River were genetically differentiated from South Caspian Sea and three other areas represented a single panmictic populations. Therefore, fisheries managements of this valuable species should be directed towards conservation of gene pools and increasing different populations

Application of microsatellite markers to determine populations of the Persian sturgeon (Acipenser persicus) in the south of Caspian Sea

The objective of this study was to analyse the population genetic structure of the Persian sturgeon (Acipenser persicus) in Sefidrud and Gorganrud rivers watershed based on the characterization of microsatellite markers during 2006 - 2008. 100 samples of Persian sturgeon were collected from two regions. Four microsatellite loci (Ls68, Spl168, Spl173 and Afu68) were analyzed for the molecular characterization of this species which resulted in polymorphic patterns. DNA bands were analysed using Biocapt and GenAlex software package. A total of 109 alleles were observed of which the maximum number of alleles (17) were found in Spl168 locus which belonged to sturgeons from Sefidrud river's watershed and the minimum number of alleles (10) in Ls68 locus belonging to the sturgeons from Gorganrud river's watershed. Results of microsatellite analysis revealed that the differences between samples of two regions were not statistically significant (p>0.05), neither for the average number of alleles per locus nor for observed heterozygosities. The calculated Fst and Rst between two regions was 0.07 and 0.17 showing that the genetic difference was significant (p< 0.01). Samples from Sefidrud river's watershed in Spl173, Afu68 and Spl168 loci and samples of other regions in Afu68 and Spl168 loci were at Hardy-Weinberg equation. The genetic distance was calculated as 0.4 which represents a significant genetic difference between samples of two studied areas. In conclusion, this study suggests that the Persian sturgeons in two regions of the southern part of the Caspian Sea are genetically differentiated, therefore fisheries management of these unique stocks for restocking and conservation of gene pools is highly recommended

Stock assessment of sturgeon fishes in the southern part of Caspian Sea (Iranian water)

The marine survey for sturgeon stock assessment was conducted in summer, winter and spring in the years 2006 and 2009 to estimate the relative and absolute abundance and percentage composition of each species in the Guilan, Mazandaran and Golestan Provinces. This survey was carried out in the Iranian waters of the Caspian Sea on board the Sisara2 and Guilan vessels using trawl nets at 2-100 m depths. Trawling was carried out in 85 stations that were selected using a stratified random design. The number of stations in each scope was based on the area of the scope in terms of the total area. Trawling and sampling in shallow water up to 10 m were carried out using 9 m trawl nets whereas 24.7 m trawl nets were used for depths more than 10 m. Trawl surveys were carried out in the daytime. Trawling velocity was kept at 2.5-3 kts and trawls lasted half an hour in order to calculate abundance, and biomass of sturgeons using the swept area method. Catch per unit area (CPUA) in the winter 2006 survey was 3853 specimens nm^2 , in the summer and winter 2007 survey was 1854 , 2912 specimens nm^2 at depths less than 10 m respectively . CPUA for sturgeons in spring 2008 survey was 2103 specimens nm2 at depths less than 10 m and 393 specimens nm2 at depths greater than 10 m (10-100 m depth). These values in the winter 2008 survey dropped to 44 specimens nm^2 at depths at depths above 10 m. CPUA for sturgeons in the spring 2009 survey was 300 specimens nm^2 at depths less than 10 m and 307 specimens nm^2 at depths greater than 10 m. In all the surveys conducted CPUA for A. persicus was higher than that for the other sturgeon species. Based on the calculations carried out in the marine survey in winter 2006 the estimated absolute abundance for sturgeons was about 2977.363 thousand. The total biomass of sturgeon was estimated as 131.713 tons. In the summer 2007 survey total abundance was estimated 1432.398 thousand, and total biomass of sturgeons was estimated at about 312.161 tons. In the winter 2007 survey total abundance for sturgeons was estimated at about 2250.105 thousand, and total biomass was estimated 578.08 tons. In the spring 2008 survey total abundance was estimated at about 3002.832 thousand. The total biomass was estimated at about 2533.318 tons .In the winter 2008 survey total abundance was estimated at about 152.722 thousand, and total biomass in winter 2008 was estimated 170.540 tons. Total abundance in spring 2009 survey was 1310.232 thousand and total biomass was estimated at 2019.tons. Investigation of stomach content of sturgeon Acipenser persicus caught under 10m depth in 2006 to 2007 surveys showed that there is significant difference in the consumed food. Polychaeta is the major food consumed and crustacean an the minor one(P>0.05).Also no new types of food( such as bony fishes or benthic) have been observed in food chain of Acipenser persicus only the food consumption rate has been related to the season of year and increases or decreases in warm or cold seasons, respectively For physiological study and determination of sexual maturation stages in sturgeon,119 gonad sampling prepared. The results showed that 63 % of fishes were females and 37 % of them were males. Gill microscopic study shows complications such as hyperplasia, curvature, adhesion, embowed, shorting and lengthen of secondary filaments and fraught bloody. Microscopic study on liver indicates signs of cloudy inflammation, fatty degeneration, dispersion of billed secretions and cell atrophy. The population genetic structure of Persian sturgeon (Acipenser persicus) in Sefidrood and Gorganrood rivers watershed analyzed based on microsatellite markers during sturgeons assessment in 2006-2008. Results showed that Acipenser persicus in two region of south part of Caspian Sea are two independent populations