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

Study on viral nervouse necrosis (isolation, characterisation and pathogenesis) in golden grey mullet in the Caspian Sea and study of pathogenecity and possibility of transmission to the other fish species (Sturgeon fishes, Rutilus frisii kutum and reared Rainbow trout and Carp)

Study on Viral Nervouse necrosis (isolation, characterisation and pathogenesis) in Golden grey mullet in the Caspian Sea and study of pathogenecity and possibility of transmission to the other fish species (Sturgeon fishes, Rutilus frisii kutum and reared Rainbow trout and Carp) Viral Nervous Necrosis (VNN) is a worldwide disease affecting several species of cultured marine fish. For the past two decades, betanodavirus infections that cause Viral Nervous Necrosis (VNN) have emerged as major constraints on the culture and sea ranching of marine fish in almost all parts of the world. More than forty species mainly of marine origin have been so far affected and this number is likely to rise in future following the introduction of new species and the increase of aquaculture trade. Unknown acute mortality occurred in wild golden grey mullet Lisa auratus and Liza saliens in Iranian waters of Caspian Sea in recent years. In order to isolation and confirmation of causative agents of golden grey mullet mortality in the Caspian Sea, a complementary research investigation project was designed in 2005 and approved immediately in Iranian Fisheries Research Organization (IFRO). Many diagnostic aspects such as Virology (Cell culture and Elctereone Microscopy), Hemathology, Bacteriology, Histopathology, Molecular biology (NestedRT-PCR), Heavy metals measuerment and Serology (IFAT and IHC) were employed in mentioned multidiciplinary project. About 322 moribund fish samples which revealed skin darkening, erratic swimming behavior such as spiral and belly-up at rest and high distention of swimming bladder. Suspected samples were collected from coastal capture sites in iranian north proviences in 2006 till 2009. Targets tissue such as brain and eye were removed in strile condition and then kept in -80oC frezzer for cell culture and Nested-RT-PCR. Other tissue samples from liver, kidney, intestine, stomach, gill, skin and muscle, gall bladder and gonads were taken and fixed in 10% buffer formalin and same parts fixed in glutaraldehyde 3% for histopathology, IHC and EM respectively. Cytopathic effect (CPE) was observed in those cell cultures just six days after inoculation with the dilutions of the tested 312 homogenate supernatants. CPE in monolayers of cells cultured (SSN-1 cell line) was characterised by thin or rounded, refractile, granular cells with vacuoles. Nine samples were positive in virology assay. Nested- RT-PCR was done on suspected tissue samples and supernatant of CPE positive samples and 21 tissue samples and all CPE positive samples were positive. IFAT was selected as a confirmatory method for identifying viral strains replicating on cell cultures and carried out with rabbit anti-betanodavirus serum on suspected tissue samples and some smears of CPE positive samples. Some bright points approved betanodavirus antigen and confirmed cell culture and Nested-RT-PCR findings. In fixed tissue samples widespread and massive vacuolation were observed in brain, spinal cord, retina and optical nerve. In order to confirmation of diagnostic findings , IHC was done with monoclonal antibody antibetanodavirus and some red-brown points were observed. Theses findings revealed expected viral antigens and confirmed previous results. Moreover, virus particles with 25-30 nm in diameter were visualized in infected brain and retina using positive staining in TEM. Also pathogenicity test was employed to confirm the obtained results. So Guppy fish Poecilia reticulata and sturgeon fry were used instead of the experimental host due to ease of handling and susceptibility. After 15 days post infection, guppy bathed in VNN-infected tissue culture with 104 TCID50 showed clinical signs similar to naturally infected Golden grey mullet, and the mortality rate reached up to 100% in 75 dpi. When target organs were examined by cell culture isolation, serology, and histopathology, all revealed the presence of virus in the Guppy. Suspected supernatant injected to sturgeon fry through intravitreous injection and widespread vacuolation were observed in brain and spinal cord buy IHC and Real time PCR were negative. In conclusion, with attntion to obtained results in this investigation such as ecological factors, clinical signs, histopathological, virological and bacteriological results, molecular analysis, (IHC, IFAT, PCR), TEM demonstration, serological and hematological findings, it could be confirmed that VNNV was the main causative agent for disease outbreak in Golden grey mullet in Southern coastline of Caspian Sea

Survey on health status in aquaculture sturgeons centers (Mazandaran, Guilan And Golestan Provinces)

Study of survey health management and diseases in hatcheries and fish farms can help us to knowledge and application control methods such as: prevention, treatment and increase high levels of production in hatchery and farms, finally. This survey carried out from 2005 to 2008 for 4 years in sturgeon hatcheries and farms of Golestan province. Sturgeon fishes include Huso Huso, Ship sturgeon, Acipenser persicus collected and for virology, bacteriology, fungius and hematology examined. Also, physicochemical parameters measured and recorded in different stages of culture. Results of this study showed that all of samples in virology was negative and did not observe any doubetful causes. In bacteriology CFU was variation from 3/9 ×105 to 6/9×10. The most parasites that detected in this survey was Cocolanus espherolanus, Sceria binopsulus semiarmatus and Amphilina fuliacea that separates from Acipenser Percicus, especially. The results about hematology parameters some important hematological indices of ship sturgeon include: The total RBC for female and mail specimens measured as 5.3±1.5 ×10^5, 4.8±0.5×10^5 per mm^3 respectively. The amount of haematocrit and hemoglobin for female and mail determined: 34.3±2.8, 35±1.4 percent and 10.3±0.9, 8.9±0.8 gr/dl .The MCV: 216.3± 96.2, 736.5± 102.5, MCH: 720.2±309.5, 186±0.7 and MCHC: 30±0.8, 25.5±3.4 percent respectively.The total WBC were (female, male): 21320±1054, 20580±777 per mm^3 and neutrophil: 16.4±2.5, 17±1.4 percent and lymphocyte: 74.4±2.4, 73.5± 0.7 percent and eosinophil: 6±1.4, 6.4±0.5 percent, monocyte: 2.8±0.8, 3.5±0.7 percent. There was not any significant differences (p>0.05) between mentioned parameters in male and female (students t-test). Also evaluation of hematological parameters in bluga ( Huso huso) include: total RBC were (male , female) 5±0.3 ×105 , 4.9±0.6 ×105 per mm^3 ,respectively and hematocrit: 33.2±6.7 , 35.4±3.4 percent and hemoglobin: 11.2±1.5 , 12.2±1gr/dl and MCV: 669.9±172.2, 723.9±982.4 and MCH: 226.2±42.5, 249.5±35.4 and MCHC: 34.1±2.4, 34.6±3.6 percent respectively. The totals WBC were (male, female): 24800±707.1, 23042±1375.4 per mm^3 and neutrophil: 18.5±0.7, 21.4±1.1 percent and lymphocyte: 73.5±1.4, 68.4±1.1 percent and eosinophil: 5±2.8, 7±1.2 percent and monocyte: 3.5±3.5, 3.2±0.8 percent. According to statistically study the count of lymphocyte had significant difference between male and female fish and this count in male was higher than female. (p≥0.05)