5 research outputs found
Determination of lethal range and median lethal concentration (LC50 96h) values of diazinon on Caspian Sea common bream (Abramis brama)
Pesticides are environmental contaminants which normally enter to aquatic ecosystems after being used in aquaculture. In this research, acute toxicity of diazinon was studied on Caspian Sea common bream (Abramis brama). This pesticide may enter in aquatic food chain and cause serious problems for aquatic organisms as well as human. The acute toxicity test was performed during 96h in static renewal system based on the standard method proposed by OECD. A range finding test was carried out in aquariums containing 10L of test solution to determine the lethal range of diazinon on fish. The acute toxicity test was then preformed in 5 treatments and 3 triplicates for each treatment. Obtained data were analyzed using probit analysis with %5 confidence limit. According to the results, LC_50 24h, LC_50 48h, LC_50 72h and LC_50 96h of diazinon on Caspian Sea common bream was 10.974, 10.391, 9.134 and 7.316 respectively. The maximum acceptable toxicant concentration (MATC) of diazinon on Caspian Sea common bream was 0.073 mg/l and the lowest observed effect concentration which is equal to LC_50 96h was 2.63 mg/l. According to the results and comparing with other studies, it can be discussed that Caspian Sea common bream is more resistant against diazinon rather than other fish species. In addition, lethal toxicity of diazinon takes place in a moderate range of toxicant concentrations
Determination of optional weight and length of Persian sturgeon's fingerling Acipenser persicus on the salinity index in the southern part of Caspian Sea
The Persian Sturgeon, Acipenser persicus is the most important sturgeon species in the southern part of the Caspian Sea and it provides 51% of Iran's caviar production. We were used five different age groups of the larvae (7, 17, 22, 28 and 33 days after yolk absorption) in 3 replicates. The larvae were all transferred at the same time to 27 liter aquarium holding 15 liter of water at different salinities (0.5, 7 and 9 ppt) and were provided with continuous aeration. Analysis of data showed that during early stages of life, age is an important factor for development of osmoregulatory organs. However, in later stages, weight and length play a vital role in this regard. The present study reveals that during post hatch and active feeding, in favorable environmental and rearing condition A. persicus fingerlings could be released into rivers and estuaries in Guilan province at an age of 33-35 days after yolk sac absorption and when they attain weight of 1.8-2.4g and length of 6.2-7.5cm
Study on the propagation possibility in reared great sturgeon, Huso huso by GnRH synthetic hormone for production of fingerling
This study was carried out in the International Sturgeon Research Institute of Dr. Dadman during 2007–2011. A total of 24 beluga 7- year – old (Huso huso) including 8 males and 16 females were selected after morphological assay, biopsy and sexing based on histological routine methods and then stocked separately based on sex in 3 concrete circled ponds (with 4m diameter, 1.5 depth) an were fed by diet include 38–40 % protein, 13–15 % fat, 19.5 – 20 Mg/kg energy and 2-3 % different kind of vitamins and minerals produced by mentioned institute. Bleeding was carried out in order to separating serum for study on biochemical and hormonal parameters. The GnRH hormone was injected to fishes at two stages each 12 hours after GV detection, evaluation of sexual hormone levels and water temperature. Females were injected at two stages each 6 hours with ration 20% to 80 % and concentration of 10 µg/kg of fish body weight. Males were injected by GnRH for one time according with the second injection in females with concentration 20 µg/kg of fish body weight. Obtaining of eggs was carried out by micro incision of oviduct without killing fish. Mean concentration of Glucose showed no significance different at stages II and III, but showed significance different at stage IVof sexual maturation stages (P<0.05). Cholesterol, triglycerides and total lipid levels of males and females blood serum were changed significantly from stage II to stage IV and in different seasons (P<0.05). Calcium level of blood serum was different at various sexual maturity stages in males and females and was more in females than males at each stage. So that showed significant difference at stage III between them. Sodium ion showed no significant difference in males and females at each condition. Mean concentration of testosterone (T) in males and females at stages II, III and IV was 10.86 ± 1.63, 0.84 ± 0.12, 54.14 ± 3.1, 15.66 ± 2.18, 112.41 ± 7.4 and 50.75 ± 3.63 ng/ml respectively, that showed significant difference with each other and at different sexual maturity stages (P<0.05), that reached to a maxim in males at stage III and IV in Autumn and in females at stages II and III in Winter. But, at stage IV, it was similar to males. Testosterone levels at all stages in males was more than females. Mean concentration of progesterone level in males and females at stages II, III and IV was 0.5±0.01, 0.5±0.00, 0.5±0.08, 0.11±0.02, 0.36±0.04 and 0.19±0.03 ng/ml respectively, that showed significant difference at stage III. But showed similar results in males and females seasonally. Estradiol (E2) level in males and females at stages II, III and IV was 9±1.39, 5.45±0.29, 6.51±0.64, 9.47±0.97, 2.95±2.29 and 4.15±0.7 ng/ml, respectively that showed significant difference in males and females at different stages (P<0.05). Results showed that by good management and using endocrinology sciences (such as biochemical and hormonal indices), we can produce breeders with having good quality eggs and sperms for artificial propagation by using micro incision of oviduct method in order to without killing them (for several time breeding), caviar and farmed larvae and fry. Results also showed that Testosterone (T), Estradiol and Calcium were the most important detective indices for sexual maturity and the accurate time of synthetic hormone injection for artificial breeding. Testosterone (T) level limit in males and females for positive reply to artificial propagation was 90–120 and 40–60 ng/ml, respectively. By using the obtained results, we can reduce rearing cost of Huso huso, because the decrease of sexual maturity duration, increase of propagation recruitment, decrease of pressure to natural sources and help to restocking, commercializing of it for improvement of sturgeon rearing and propagation in order to caviar and fry production
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
Determination of suitable size of Rutilus frisii kutum for releasing by evaluation of osmotic regulation ability
The study was done in Nutrition and Live Food Station was located in Bandar Anzali Ghaziyan. Juveniles weighted average 0.5, 1, 2.5, 5, 10, 15 and 20 g were randomly selected in three water conditions with a salinity of 11 ppt (Caspian sea water), water 7 ppt and freshwater (with three replicates per group) were included. At intervals of 0, 3, 6, 12, 24, 72, 168, 240 hours, blood samples were heparinized capillary tubes by caudal juveniles and ion concentrations Mg, Ca,Cl using the spectrophotometer and sodium and potassium ions with Flaym photometry (flame photometric), the osmotic pressure of blood plasma by osmometer and cortisol levels were measured by RIA method. To study the microstructure of gill and kidney tissue for each treatment , tissue samples by classical histological methods and stained with hematoxylin - eosin slides were prepared. The frequency and location of the enzyme Na^+, K^+ - ATPase and chloride cells with immunohistochemical localization was performed. Studies micrometric gill chloride cells and renal glomerular networks by software Image tool (version 2.0) was performed. Measurement of enzyme Na^+, K^+-ATPase, by Zaugg (1982) method was conducted. Data analyzed by one-way ANOVA (Oneway ANOVA) with Tukey's test was performed. Overall, the results of measuring ions and osmotic pressure on the tenth day of treatment, the osmotic potential juveniles 2.5, 5, 10, 20 gr in Caspian sea water and all groups except the 0.5 in water of 7 ppt confirmed. But in case of unfavorable conditions for the release in estuaries river and river, fish with weight 1 to 3 release directly to beach (where the salinity is 7 grams per liter) and fishes with weight from 10 to 20 gr to sea. Although suitable river conditions necessary condition for release of juveniles in riverine areas to adaptation juveniles occur gradually