Journal of Aquaculture Development
Year:2015 | Volume:9 | Issue:1|Papers Count:8

In this trial, the effect of the different light intensities were studied on rotifer culture (Brachionus rotundiformis).Treatments consist of 10 ml vials that contained 3 ml marine algae Nannochloropsis oculata at a density of 12×106cell.ml-1 and inoculated with rotifers at a density of 10 individuals. ml-1 in different light intensities (200, 1000, 2000, 3000, 4000, 5000 and 7000 lux) and All of the the culture conditions (temperature 28o-32o, salinity 25ppt, pH7.9-8.1, algal density and ventilation was done by manual shaking of vials) were stable excepted light intensity. The result of the experiment show that the light intensity has not significant on rotifer density after 12 h (p>0.05). The compare of the rotifer density after 24 h indicated the Maximum of the rotifer obtained in 3000 lux treatment (34±8.71) that has a significant of all treatments excepted 4000 lux (p<0.05).The study on the rotifer calture after 36, 48, 60 and 72 h, showed that the more density of the rotifer was 3000 lux treatment that has significant with other treatments (p<0.05) and so after 72h, 255±19 rotifers per ml was obtained in a 3000 lux.so statistical analysis of the egg rotifer showed that has a significant of all treatments after 12 to 72 h in the different light intensities (p<0.05) and the maximum of egg production was obtained in 3000 lux (122±41.5) and the minimum of that was obtained in 7000 lux (4.00±1.0). The index of the lorica and egg diameter have no significant among treatments in a all of the period experiments (p>0.05). After 72h The minimum of rotifer production was obtained in 7000 lux (57.6±20.5) and the maximum of that was obtained in 3000 lux (255±19). As a result with increasing light intensity (3000lux), the rotifer density also increased but it decreased in higher light intensity.

In order to collect information on the occurrence of wild Artemia populations in hypersaline environments such as salt lakes, lagoons and salty rivers, field surveys were conducted between 1980 to 1990. The reproduction behavior of Artemia populations and the presence or absence of males was carefully recorded. Sampling involved the use of plankton nets. Collected cysts were characterized on the basis of their diameter and chorion thickness, while nauplii (instar-I) were characterized on the basis of their total length. Artemia populations were found at 18 diferent geographical locations scattered over 12 Iranian provinces. All Iranian Artemia populations are parthenogenetic with the exception of Artemia urmiana from Urmia Lake. During the last five years severe salinity increase has caused a dramatic reduction of population sizes in several hypersaline settings in Iran. The study of cyst and naupli biometry revealed substantial di, erences between populations and can be used, to some extent, for their discrimination. Cyst diameter means values range from 243.2 to 285.4 mm. For some Iranian parthenogenesis, cyst diameters were among the smallest recorded so far for parthenogenetic Artemia. The total length of newly hatched nauplii ranges from 455.5 to 529.8 mm.

The present study was conducted to investigate the effects of co-culturing of Western white shrimp, Litopenaeus vannamei and grey mullet, Mugil cephalus on diversity and incidence of vibrio bacteria from shrimp ponds during 4 months experiment. 9 earthen ponds (600 m2) as three treatments with three replicates were established in Gwadar area (located in the coastal area of Oman Sea, southeastern of Iran). The shrimp post-larvae (PL) 0.007±0.001 g in weight were stocked at density of 20 post-larvae/m2 in each experimental pond. After 40 days shrimp stocking, mullets with size of 20-50 cm were stocked at densities of 0 (control group), 2 (Treatment 1) and 4 (Treatment 2) fish per 100 m2 of ponds respectively. For bacterial study, shrimps were captured monthly as alive and tissue samples taken from gill, Hemolymph and hepatopancreas. According to bacterial inoculation data, six bacterial species including Vibrio alginoliticus, Vibrio fluvialis, Vibrio costicula, Vibrio splendidus, Vibrio nerets, Vibrio natrigenes. Bacterial incidence percent in treatment 1 (2.46%) and 2 (3.7%) were significantly lower than control group (23.47%) (P<0.05). Also, identified vibrio species in each experimental group were: (control group): Vibrio alginoliticus, Vibrio fluvialis, Vibrio costicula, Vibrio splendidus, Vibrio nerets, Vibrio natrigenes, (Treatment 1): Vibrio alginoliticus, Vibrio fluvialis, (Treatment 2): Vibrio natrigenes. In conclusion, our results show that grey mullet as a secondary species has positive effect on control of vibrio spp. of white shrimp. Likely, this effect indirectly returns to reducing of organic matter content of sediment and improvement of water quality by mullet.

Esox Lucius (Linnaeus, 1758) is an economic fish of the Caspian Sea Basin that live in some areas such as the rivers with aquatic plants and wetlands. This fish reproduce in freshwater ecosystems that there is little information available about it. Study of gonadal steroid hormones of pike broodstocks is one of the important indicators of reproductive biology. So, the gonadal steroid hormones of pike broodstocks of Anzali wetland studied from autumn 2010 to summer 2011. For this purpose, we caught 50 pike from Anzali wetland. Then, the fishes biometry and after of bleeding and transfer blood to CBC tubes, plasma was extracted using of a centrifuge. Then, The measurement of hormones of 17b-estradiol, 17a-hydroxy progesterone and testosterone were measured. The results of sex steroids levels of plasma showed, increase of 17b-estradiol hormone levels in autumn, increase of testosterone hormone levels in winter and 17a-hydroxy progesterone hormone levels in the autumn and winter (p<0.05).

The acute toxicity and histopathology of Kutum exposed to sevin was performed statically in 20±2oC. In this experiments the mean body weight of the juveniles was 2.98±0.46 g. The 96h LC50 value of sevin for Kutum juveniles was 3.0654 mg/l Therefore the MAC value of sevin in natural waters for Rutilus frisii kutum was 0.765 mg/l. According to the table of sorting the toxicity of insecticides, sevin was "Moderately Toxic" for caspian white fish.The clinical symptoms of caspian white fish juveniles exposed to sevin were consisted of abnormal swiming, losing the balance and swimming in a half circle, block of respiration movements and losining the normal color. Histopathological experiments performed on control and experimental specimens of caspian white fish with 3.1±0.23 g mean body weight after 96h exposure to sevin in concentration lower than LC50 96h (3 mg/l). Samples were taken from tissues of liver, kidney, gills, spleen, gut and mussels in both experimental and control groups. Sever hyperplasia, edema, inflamation and degenaratin of lamellas were observed in tissues of gills in experimental group. Also vacuolization, necrosis and multifocal hemosiderosis were seen in liver and spleen. More than this lesions, there was kidney’s tissue necrosis and enlargement of bowman’s capsule In kidney’s tissue. As the result of this research, it is concluded that histopathology of these juveniles exposed to environmental contaminants may provide useful information as to target organs and mechanism of toxic substance actions.

Development of fish farms requires of studying about determines the confidence interval between farms. Confidence interval indicative the minimum distance required to minimize the adverse effects of spreading pollutants between farms. In this investigation, the result of Mike 21 FM model to determine the confidence interval between culture farms in the Gorgan Bay is discussed. The effects of waves radiation stress induced of dominant wind by implementation of the wave model of MIKE 21 NSW in 7 scenarios are considered in the hydrodynamic model of MIKE 21 FM. Pollution transport and dispersion modeling were done under 14 different scenarios by coupling hydrodynamic Mike21FM with Advection-Dispersion models. In modeling, average annual precipitation, evaporation and 13 river inlets and the effect of western, northern and west northern winds with two speeds 2.5 and 5 m/s in normal atmospheric conditions and prevailing western wind with speed 15 m/s under storm condition were used. To applying the open boundary at the mouth Ashouradeh-Bandar Turkmen, mean discharge values of input and output of 1, 000 m3/s were used. The modeling results showed that the confidence interval varies from 45 to 1097 m in the Gorgan Bay. The confidence interval and duration of the dilution of pollutants in the bay increased by reducing depth and vice versa. The confidence interval increased with increasing wind speed, but the time needed for dilution of pollutants in the bay by increasing the mixing process decreases and vice versa. Water exit through the mouth of Ashuradeh-Bandar Turkmen caused to increased confidence interval and duration of the dilution of pollution and vice versa.

One of the most important breeding-related issues of common carp is artificial reproduction and studying the fecundity status as a quantitative index in reproduction. For this reason, we investigated the effect of female age of common carp on reproductive and morphological indices including weight, length, condition factor, eggs weight, fecundity, number of eggs per gram, and relative fecundity per weight and length. For this purpose, two groups of females (2 and 3 years old) were compared. The 3-year-old fish showed higher average weight (4536.7±713.0 g), total length (64.9±3.1 cm), obtained eggs (664.3±69.9 g), working fecundity (600847.3±91984.4 eggs), and relative fecundity per length (74748.8 ±2194.2 eggs) than the 2-year-old fish (P<0.05). Also, condition factor (1.8±0.2), number of eggs per gram (1000.7±137.8), and relative fecundity per weight (1646943.3±51362.9 eggs) in the 2-year-old fish were higher than those in the 3-year-old fish (P<0.05). The comparison of two age groups of fish showed that there is a significant difference in all measured parameters. Increase in age, weight and length of common carp broodstocks had positive effect on fecundity, weight and size of obtained eggs, and older, heavier and larger fish showed less number of eggs per gram, while the eggs were in larger size. According to the results, common carp females with higher age, weight, and size are more appropriate for artificial reproduction.

The aim of this study was evaluating the nutritional value of common carp (Cyprinus carpio) in the ripeness and sexual rest stages in two areas Behshahr and Anzali wetland.20 specimens of common carp were collected randomly in autumn and spring from two areas Behshahr and Anzali wetland in south Caspian Sea. After sampling, specimens were frozen and transferred to the laboratory for further biometric parameters measurements. The biometric results didn’t show any different significant in total length and weight between two areas Behshahr and Anzali wetland. Comparison between two stages, total weight in sexual rest stage was more than ripeness stage (P<0.05) but didn’t show any difference significant in total length. The lipid content was not different significant between two areas. But the protein, moisture and ash content were different (P<0.05). The protein, moisture and ash content were different between stages (P<0.05) but not in total lipid. The moisture and ash content in sexual rest stage were higher and significant (P<0.05). The lipid and protein content in sexual rest stage were higher and the protein content was significant (P<0.05) but not in total lipid. Therefore, it seems that common carp consumption in ripeness stage comes along with more amounts of protein.