NEW TECHNOLOGIES IN AQUACULTURE DEVELOPMENT (JOURNAL OF FISHERIES)
Year:2009 | Volume:3 | Issue:2|Papers Count:15

The fat of fish roe contains unsaturated fatty acids, like their fillet. The present study was conducted to determine the fatty acid profile of fresh and salted roe in Caspian Sea Kutum fish (Rutilus frisii kutum) and Golden mullet (Liza aurata). The fish roes were divided in two groups and the fatty acids of fresh roe were determined after oil extraction and methylation by Gaschromatography.Then, other roes were salted by bringing in saltwater during 14 days and their fat and fatty acids profile was determined. The fat contents of fresh and salted roes were 5.80 and 2.83% in Kutum and 7.38 and 5.62% in Golden mullet, respectively. The results showed that unsaturated fatty acids of fresh Kutum and Mullet roes were 58.59 and 65.19%, respectively, and 45.72 and 56.61% in salted roes. The results indicated that salting is not only a proper way for conserving, but also by decreasing the fat of the fish roe, it will have an effect on preserving fatty acids specially omega3 & omega6.

This study was carried out to evaluate the influence of Avizyme multi enzyme and replacement of fish meal protein by soy bean meal protein on growth performance and survival rate of rainbow trout (Oncorhynchus mykiss). Experimental diets containing four levels of replacement (25, 50, 75 and 100%) and three levels of Avizyme multi enzyme (0, 500, 1000 units/kg) were formulated and prepared. By the means a diet with fish meal as the only source of protein was used as the control.Thirteen treatments and three replicates were used in this study. Specimens in 89.40±4.01gr mean weight were stocked in aboundance of 30 fish per each tank and fed experimental diets during the 8 weeks period of study. The results showed that supplementary multi enzyme (Avizyme) caused an increase in growth and survival rate. Effects of enzyme were positive and 1000 ppm showed the best results with at least 39% replacement of fish meal by soy bean meal as a suitable formula for rainbow trout.

An experiment was conducted to evaluate the effect of feeding frequencies and stocking size on growth and food conversion ratio (FCR) of rainbow trout (Oncorhynchus mykiss) in brackish water for 102 days. Three stocking sizes (10, 25 and 40g/fish) of rainbow trout and three fish feeding frequencies (twice, three and four times per day) were examined at the same time. The results showed that in the group with 10g initial weight increasing the feeding frequency, some growth factors like final weight, daily growth, and weight gain increased and the food conversion ratio (FCR) decreased.It means in this group (10g) two times feeding per day is not enough for an acceptable growth rate. In the two other groups (with initial weight 25 and 40g) although by increasing the feeding frequency, some growth factors had a little increase but these differences are not significant. Therefore, in rainbow trout culture with initial weight of at least 25g, two times feeding per day were enough. With connivance of feeding frequencies, the lowest FCR was in the group with 10g initial body weight and there was not any significant difference in SGR. So, according to the results, the suggestion is the fish should be stocked with 10g initial body weight.

This experiment was conducted to determine the growth model of Penaeus semisulcatus shrimp and effect of important physicochemical parameters of water on the growth of this shrimp during 109 days. Shrimps reared in three 0.4 ha ponds with density of 25 post larva per meter square in the shrimp research center Heleh Boushehr in summer, 2002. Biological and non-biological parameters recorded during farming period were total length and weight, water temperature, pH, transparency, depth, dissolved oxygen and salinity. There is a correlation between non-biological independent variables and dependent variable (specific growth ratio). According to multi regression (Backward) method, decreasing transparency, increasing depth, decreasing salinity and constancy water pH had the highest effect (r=%99) on Penaeus semisulcatus growth. The mean harvest rate, mean weight and feed conversion ratio in three Penaeus semisulcatus ponds were 903.33kg per 0.4ha, 12.22gr and 1.33, respectively.

This study was conducted to improve the feeding of Huso huso in completely randomized design in fiberglass tanks with a capacity of 1100 L under identical conditions. 300 juvenile Huso huso (215±10g) were distributed to 15 tanks each containing 20 fishes. Water flow rate was 20±2L/min with the water temperature of 15±0.4oC and the dissolved oxygen content 7.7±1mg/L during the experiment. The experimental fish were fed manually 3 times daily according to 1-2 % of body weight and depending on their apetite which lasted for a period of six weeks. The water was supplied with non-circulated filtered from a river. Five experimental diets with various levels of lipid were formulated: D1 (without added oil), D2 and D3, diet of soyabean oil (with levels, 5.35% and 17.4%, respectively), D4 and D5, diet of fish oil (with levels, 5.35% and 17.4%, respectively). At the end of the experiment, there were noticeable improvements in fish growth following the addition of different fat level in the diets. The increased fat content in the fish feed resulted in better FCR, BWI and SGR.The lowest level of cholesterol was observed in fish that were fed with D5 diet. There also appeared no significant difference in triacyl glycerol among treatments. In general, with respect to FCR, BWI, and SGR, D5 diet proved better results of growth. This can be attributed to a greater palatability of the diet which contained higher fish oil as well as to its better physiological effects.

In this study, the fish paste of silver carp has been prepared based on three formulas, and the third formula, which contained 70 percent fresh meat of big head carp, 3 percent starch, 10 percent low fat milk, 5 percent liquid oil, 3.5 percent tomato paste, 0.5 percent sodium alginate, 3 percent lemon juice, 2 percent egg, 1.75 percent casein, 1 percent salt, and 0.5 percent various spices was chosen according to organoleptic properties test. Then, the product has been divided into three parts: sample 1 (control sample), sample 2 (containing 0.01 percent antioxidant BHA) and sample 3 (containing 0.02 percent antioxidant BHA). To determine the shelf life, the samples were frozen and kept in cold store under-18oC, and during certain time intervals of 0, 15, 30, 60, and 90 days all microbial tests, peroxide value determination T.V.N, determination and measurement of fatty acids has been performed. The microbiological tests showed that the number of bacterial in 10-4 ratio reaches to 0 after 60 days in cold store, and at -18oC the number of bacterial can not determine the shelf life and there is no difficulty with fish paste TVN after 90 days. The peroxide tests showed, the peroxide can not determine the shelf life.Conclusion: according to this result the shelf life for the blank sample which contained no antioxidant is suggested 15 days and for sample which had BHA 0.01% and 0.02% of the antioxidant the suggestion is 60 days at-18oC.

The aim of this study was evaluation of Ergosan and anti-streptococcus vaccine effects on hematological factors including hematochrit, hemoglobin, the mean cell hemoglobin (MCH). The mean cell hemoglobin concenteration (MCHC), the mean cell volume (MCV), total RBC, total WBC, and diff which took place in one of fish culture farms located in a small city, Neka, in Mazandaran province in 2005. The selected fish were 5-8 grams and were divided to 4 groups including: control, vaccine, vaccine+Ergosan and Ergosan. Each group was included 3000 fish. At the end of the experimental period which took about four months, blood samples were gathered from all treatments and hematological factors were evaluated. Data analyzed through one way ANOVA, Duncan test, and Tukey. The result indicated that statistically, there was no difference among treatments considering parameters such as total RBC, hematochrit, hemoglobin, MCV, MCH, and MCHC. There was an increase in the total WBC which was not that significant in comparison with the control group. A significant difference was seen in the number of lymphocytes in experimental & control groups. The number in control group was 82% while in vaccine group it came to 98%, in Ergosan 96%, and in vaccine+Ergosan it was 95%. According to the result, it seems prescribing the vaccine and Ergosan will be stimulating for proliferation of white blood cells specially lymphocytes. Therefore, it will play an effective role in increasing fish resistance against environmental stress & pathogens.

The maximum ability of sperm for fertilization is 5-6 hours after collecting sperm from males in normal temperature. While by semen freezing and use of suitable extenders and cryoprotectants we can conserve it in liquid nitrogen for several years and we can use stored sperms in essential Conditions.Varied cryoprotectants are used in sturgeon semen cryopreservation but DMSO is the most important cryoprotectant. In this study, we have investigated the protective effect of DMSO as a cryoprotectant using different concentrations (8%, 10%, 12%, and 15%) and we have determined sperm motility rate and its motility time after thaw. The sperm of Persian sturgeon was collected from five males. They were diluted in appropriate extender containing Tris, Sacharose, egg yolk, and dimethyl sulfoxide in 1:1 ratio and the suspension were poured in to 0.5 ml straws and frozen in -196oC liquid nitrogen vapour in a three storage program. Then straws were transferred to liquid nitrogen tank. The sperm samples were thawed in 40oC water bath for 25s. The sperm motility rate and its motility time were observed using microscope. According to the results, the sperm motility rate after preservation in liquid nitrogen about 7 days were measured as 8.5±0.61, 12.54±2.57, 19±5.66, and 16.3±6.15% in concentrations 8%, 10%, 12%, and 15%, the sperm motility time after this time was 184.3±28.87, 267.3±36.54, 274±50.51, and 218±63.85s, respectively. Also the sperm motility rate after preservation in liquid nitrogen about 72 days were measured as 14.25±5.50, 10.50±1.61, 7.50±1.81, and 13.75±2.74%, the sperm motility time after this time was 195±39.50, 194.50±43.63, 154±37.34, and 221.70±47.31s, respectively. There was no statistical significant difference between selected concentrations. However, 12 and 15% of DMSO had better motility rate and time. Results indicated that the increase in concentration of DMSO from 8% to 15% does not change the percentage of motile cells and motility time on sperm cryopreservation of Persian sturgeon.

The effects of five different food including: blood worm, artemia cyst, artemia mass powder, gammarus mass powder, and ordinary commercial food were studied on Siamese fighting fish (Betta splendens) propagation efficiency during thirty days in a Randomize Totally Design with 4 times repeatition. Experimental plots had been consisted of twenty 30×30×40 (cm) aquarium which a pair of male and female brood stocks were introduced to each one. Male and female fish were separated in each plot by a glass plate for 15 days in order to get prepared for spawning. The results of experiment showed no significant difference on spawned ova, ova diameter, and hatched ova among various ration treatment, but the average of compared factors showed spawned ova, hatched ova, and ova diameter, were better in those brood stocks which had been fed by blood worm food treatment. However, ordinary commercial food treatment had the weakest results through all ration treatments.

Shemaya (Alburnus chalcoides) is one of the economically valuable fishes in the Caspian Sea. This fish enters rivers and wetlands entering the Caspian Sea for spawning. The study of fecundity is one of the important indicators of reproduction biology in fishes. The present study was conducted in the spring of 2008 on 33 shemaya specimens caught from each of the regions, the Anzali Wetland, Sefidrood, Chamkhaleh and Shirood Rivers in order to investigate the fecundity in this immigrant species. According to the results obtained the highest average fork length (15.83±1.2 cm), weight (42.71±7.98 g), gonad weight (5.54±1.81 g) and absolute fecundity (4447.84±1132.51eggs) belonged to shemaya specimens caught from the Anzali Wetland, while the lowest average fork length (13.41±0.81 cm), weight (24.51±4.55 g), gonad weight (3.54±0.88) and absolute fecundity (2613.97±548.79 eggs) were recorded in Sefidrood’s Shemaya. The maximum and minimum average relative fecundity were recorded in Shirood’s Shemaya (113.15±21.06 eggs) and Chamkhaleh’s Shemaya (101.06±22.51 eggs), respectively. Maximum (898.48±255.72) and minimum (763.94±70.62) average number of ovules in each gram of body weight belonged to Shemaya specimens belonging to Chamkhaleh River and Sefidrood River, respectively. The highest average diameter ovules (1.175±0.04 mm) and the average mean gonadsomatic index (14.72%) belonged to Sefidrood’s Shemaya, while the lowest average diameter ovules (1.106±0.117 mm) and average mean gonadsomatic index (12.15%) were recorded in Chamkhaleh’s Shemaya. On the basis of Kruskal-Wallis and Mann Whitney tests, significant differences were detected in the biometry parameters and fecundity of Shemaya specimens from different regions.