Iranian Scientific Fisheries Journal
Year:2011 | Volume:20 | Issue:3|Papers Count:24

The purpose of this study was production of fish protein isolate and surimi from silver carp (Hypophthalmichthys molitrix)and survey of color characteristics as well as chemical changes of gel and powders of those products. In this research, proteins were isolated using pH shifts method. Acidic pH (2.5 and 3.5) and basic pH (11 and 12) were used to produce fish protein isolate. Three steps of washing cycles were used for surimi production, and in the third step 0.2% NaCI was used for more dehydration. Results showed that the product efficiency for fish protein isolate was significantly more than the surimi. Furthermore, the produced fish protein isolate using acidic pH had the highest production efficiency amongst the samples. As a result, fish protein isolate had more recovery protein content compared to surimi.Determination of fat content of the samples showed that surimi contained significantly lower reduction in fat compared to fish protein isolate. Investigation and comparison of color characteristics (L, a, b) attributed to gel and powder forms of the samples demonstrated that the produced fish protein isolate using pH 2.5 had the most intense lightness (L parameter) amongst the other samples. This study clearly showed that the production efficiency of fish protein isolate was higher than surimi. In addition, due to the process of surimi production, fish protein isolate had more protein content. The higher reduction of fat content of fish protein isolate can be considered as an advantage because of possible increase in durability and safety of the products.

In order to assess the maximum replacement possibility of unicellular green algae with cheap food sources for feeding Artemia, two strains of Artemia urmiana and parthenogenetic Artemia were fed under laboratory condition using wheat bran, soybean meal and 50/50% mixed diet of wheat bran/soybean, each in 12 different concentrations together with different rations of Dunaliella salina for 15 days. The results were compared with those fed only on algae D. salina as control group. At the end of the experiment, control groups in each two strains (with 9.11mm growth and 86.25% survival in A. urmiana and 8.55mm growth and 85% survival in parthenogenetic Artemia) had almost the best condition. In A. urmiana treatments 95.8-88% replacement for algae of wheat bran, treatment 94% replacement for algae of soybean and treatments 97-94% replacement for algae of mixed wheat bran/ soybean showed no significant differences with control in both growth and survival. In parthenogenetic Artemia treatments 94-82% replacement for algae of wheat bran, treatments 91-88% replacement for algae of soybean and treatments 91-82% replacement for algae of mixed wheat bran/soybean showed no significant differences with their control in both growth and survival. According to the results, it seems that single-cell algae and their production requires exorbitant spending and personnel which can be replaced with easily affordable agricultural wastes, without need to specialized staff.

To determine the suitable locations for installation of artificial reefs we studied Persian Gulf waters (Hormuzgan province) from December 2006 to March 2007 seasonally. The area was stratified to 10 transects and each transect was divided to three layers and used random sampling method. Habitats of fauna and flora including: Communities of corals, seaweeds, sea cucumbers and sea grasses, and sedimentation depth using SCUBA diving method were studied in each transect and layer. Sea grass communities existed in some places with below lam depth of Bandar Mesan, Bandar Kang, Kish Island and Bandar Chirooyeh transects. Also, seaweed habitats were seen in Bandar Mesan and some areas in Bandar Lengeh and Kish Island in la-20m depth transect. The study of coral and sea cucumber communities indicated presence of Acropora sp. habitats in Bahman jetty, Bandar Mesan and Bandar Bostaneh transects, and Porites sp. habitats in Hengam island transect, Holothuria sp. habitats in Bandar mas en and Bandar Lengeh transects and Stichopus sp. habitat in Hengam Island transect. All these species were found in shallow waters bellow 10 meters depth and showed a patchy distribution. Sedimentation depth results showed a statistically significant difference between layer<10m in Bandar Salakh and the same layers in other transects, also between layer la-20m and 20-30m in other transects. Based on the sedimentation depth and habitats studies, we recommend layer la-20m in Bandar Lengeh area and Bandar Lengeh to Hendurabi Island area as suitable for artificial reefs installation.

The physicochemical and sensory quality changes of silver carp(Hypophthalmichthys molitrix)surimi were studied during three months at frozen storage (-18oC). The results showed that with increasing storage time of surimi from silver carp, TVB-N, peroxide value (PV) and expressible moisture increased significantly. TVB-N increased from 10±1 to 16.80±1.4mg%, Peroxide value from zero to 2.76±0.85 meqO2/kg and expressible moisture from 4.23±0.13 to 6.32±0.13% during three months at frozen storage. Quality score of sensory evaluation, folding test and biting test were significantly decreased during storage period. Quality score of produced surimi gel decreased from AA to A, C grade and biting test decreased from 8.58±0.98 to 5.25±1.86. The results indicated that in spite of increasing of TVB-N, PV, expressible moisture and decrease of sensory quality score, folding test and biting test of silver carp surimi, the samples were between allowed limits and acceptable after three months at frozen storage.

Genetic diversity of Metapenaeus affinis population from the northern coasts of the Persian Gulf (Bahrakan, Lifeh-Boosiaf) was studies using microsatellite markers. During September to October 2007, 60 samples of pleopods tissue of the shrimp were taken and genomic DNA was extracted by acetate method. peR was performed on microsatellite primers. To measure fragment size, samples were run on an 8% polyacrylamid gel. For each microsatellite locus, using genetic software, Pop Gene and Gene Alex, allele frequency, real and expected heterozygosity, Fst and Rst and other relevant factors were measured. Of the obtained 5 paired microsatellite primers, all were polymorphic. The mean observed and effective alleles number was 7 and 3.67, respectively and also the mean observed and expected heterozygosis was 0.27 and 0.66, respectively. It was also seen that specimens from all regions were not in Hardy-Weinberg Equibrium in all of the loci. Based on the analysis of molecular variance (AMOVA) Fst, Rst and Nm were 0.107, 0.372 and 2.092, respectively. The highest genetic distance was 0.571 and the lowest was 0.561. The present study showed that two different populations of Metapenaeus affinis are living in the Bahrakan and Lifeh-Boosiaf region northwest coasts of the Persian Gulf.

Effects of different concentrations of Diazinon on Roach Torkemani (Rutilus rutilus caspiusi fries supplied from Ghareh-Soo Fishery Research Station was studied in Gorgan University of Agricultural Science and Natural Resources in 2009 to determine 50% lethal concentration (LC50) for the fish within 96 hours. In this study, 126 Roach fries with mean weight of 3 grams were used. Tests were performed statically based on instructions of O.E.C.O under fixed water quality conditions at the temperature 24±1 and pH 8-8.5 in a completely random trial with five concentrations treatments of Diazinon (5, 5.95, 7.07, 8.48 and 10mg/l) in three replications and the means were compared using Duncan test at 5% significance level. The results indicated that at the end of 96-hour test, LC50 was 7.88mg/1. In this test, clinical signs such as hunched spinal column, thrilling, clot in caudal fin and head, and irregular swimming were observed in the studied fish specimens. In hematological examination, there was a remarkable decrease in percent of hematocrit between concentrations of 5 and 5.95mg/1 of Diazinon. By increasing the concentration of this poison, the decrease became slower. Furthermore, there was a significant difference in percent of hematocrit between control group and LC50 group, with mean amounts of 36 and 27%, respectively. Based on the results, Diazinon wasclassified as toxic pesticide for Roach Torkemani.

The effects of using different of gammarus meal levels (0, 5, 10 and 20%) instead of kilk fish meal as a protein source on growth performance, feed conversion ratio and survival of rainbow trout (Oncorhynchus mykiss) fingerlings were studied over 8 weeks. Rainbow trout fingerlings (mean body weight 5.48±0.32g) were reared in a completely randomized design with three replications in the same conditions. Based on the results, no significant difference was observed in the final length and weight and specific growth rate among treatments.Increase of gammarus meal in diet led to increase of feed conversion ratio and decrease of survival, but the difference was not significant among treatments. Commercial analysis showed that the cost price of feed increased with increase of gammarus meal in diet, significantly. Thus, results of our study showed that adding up to 10% of gammarus meal instead of kilka fish meal in rainbow trout fingerlings diet is suitable, considering gammarus abundance in the shores of south Caspian Sea and lack of significance in difference on growth, feed conversion ratio and survival.

To study moving direction and survival index of Persian sturgeon fingerlings, a total of 390200 individuals of the fish in three weight classes: less than 3g, 3 to 5g and 6 to10g were marked by coded wire tags (CWT) during 2003 to 2008. In 2003, 101500 of these individuals were marked in Shahid Beheshti, Shahid Rajaee and Shahid Marjani Sturgeon Rearing Centers, in north of Iran and then released in Sephidrud, Tajan and Gorganrud rivers. During 2004 to 2008, 288700 pieces were marked by Shahid Beheshti Rearing Centers and released in Sephidrud River. Catch and detection of fingerlings carried out by gill net prepared from nylon with mesh sizes 22, 26, 33 (2 filaments for each mesh) and one 40mm mesh size.Totally, 175 meters of net was used to study fishes in waters under 10m depth in Guilan province. In all, 2827 pieces of this fish were caught of which 40 had CWT and these belonged to weight classes 6-10g (22 pieces), 3-5g (17 pieces) and under 3g (one piece).Results on release and catch of the fingerlings for Sephirud River showed that more than 70% of fingerlings moved to eastern parts of the estuary and eastern coasts of Guilan province (stations like 12 Bahman, Dastak and Chaboksar). Of the fingerlings released in Gorganrud and Tajan rivers, only one piece was caught in Chaboksar and another in Lisar after 15 months. Hence, we postulated that the fingerlings released in Mazandaran and Golestan provices migrated to Guilan province coasts. Statistical analysis of the survival index in different weight classes indicated that the class 6-10g had higher survival rate, twice than class 3-5g and 20 times more than that of the class under 3g. Considering these results, probably the higher weight at release time can be effective in increasing the survival rate of the Persian sturgeon fingerlings.

Replacing live food with artificial diets in aquatic larviculture, especially in shrimp larvae not only is caused convenience feeding, but also in economical view is very important. With this object, in this survey, a density of 100.L-1 white leg shrimp larvae in 9 nutritional treatments each with three replicates were cultured in 20L tanks each one was held with 10L of 30% salty water using one air stone. The larvae were fed 4 times. Day-1 with different diets, including live foods (Cheatoceros gracilis and Artemia nauplii), artificial diets (handmade and imported) and different combinations. The results showed that the growth rate and survival percentage in larvae fed with combination feed treatments, were more desirable than those fed with food and feed treatments and feeding with handmade and imported feeds alone, raised high mortality in shrimp larvae during the experiment. Also, it was denoted that even if the zoea larvae has been fed with live food, feeding with 100% artificial diets for the resting larviculture period won't be possible because of decreasing significantly in growth rate, total length and survival percent of shrimp larvae, compare to the other treatments. In addition, replacing partly of live food with artificial diet without adverse affects on growth and survival rates of white leg shrimp larvae will be possible and the observation supported that the handmade feed with given formulation, had more suitable results comparing to the imported one for mixing with live food economically. Therefore, we recommend that a mixture the formulated diet and algae plus Artemia nauplii is used for culturing white shrimp larvae.

Monthly sampling of red algae was carried out from April 2005 to March 2006 in Chabahar coasts (southestern of Iran) along Sistan & Baluchistan province coastal waters. We considered monthly periods of maximum tide according to tide tables. Then seaweed growth area in intertidal zones was deterrnind through GPS, GIS and satellite imagery. Monthly sampling was conducted on a number of transects with equal distance and in randomly chosen 50x50cm quadrates. The samples were transfered to Offshore Waters Research Center's lab and after cleaning and separating, the weight of each species recognized was measuerd according to the present references. The biomass of each species was obtained per area unit and in the total area after deterrning the average weight of species. During this research, 13 species of medicinal red algae were recognized, and the most important families included: Gelidiaceae, Gracilariaceae, Hypneaceae and Rhodomelaceae. Total biomass in the area of Chabahar Coasts were 865.2 tons and the monthly average was 72.1 tons. The maximum biomass was obtained in February as 149.8 tons (828g/m2) and the minimum biomass was seen in Mayas 16.3 tons (90.2g/m2). The maximum biomass belonged to Gracilaria corticata (%33.1) and the minimum biomass toHypneapannosa (%1).

Due to the importance of adult Artemia in aquaculture, information regarding the digestive enzyme activities variation with inexpensive diets has great importance in Artemia at different life stages. In this study, the effect of different inexpensive diets on digestive enzyme activities, including trypsin, amylase and lipase of Artemia urmiana was investigated in different life stages. The experiment was carried out with 5 treatments and each with 2 replicates over 15 days using 5 diets (wheat meal, common carp diet, soybean meal, a mixture of soybean meal and canola meal (compound diet 1) and a mixture of soybean meal and wheat meal (compound diet 2) in a completely random design. Nauplii were introduced to their cultivation environments after hatching and the digestive enzyme activities were measured in days 5, 10 and 15 of the experiment. Positive and significant correlation were observed between the crude protein content of the diets and trypsin activity (0.74), the carbohydrate content of the diets and amylase activity (0.49), and crude fat content of the diets and lipase activity (0.84). The activities of all enzymes were increased with the Artemia development in this study. During the experimental period, the trypsin, activities were increased in all treatments with the exception of wheat meal treatment, amylase activities were increased in all treatments and lipase activities were increased in all treatments with the exception of common carp diet and wheat meal treatments. Digestive enzyme activities were affected by the diets and Artemia life stages. Regarding the increasing digestive enzyme activities until adult stage in Artemia urmiana, using adult Artemia urmiana decreases pressure on resources of Artemia cyst and nauplii in natural environments. In addition, this condition may result in more economic returns and better quality of adult Artemia compared to its cyst and nauplii.

Macro-invertebrates playa key role in freshwater lentic and lotic ecosystems. Lake Neor is located in northwest of Iran, southeast of Ardebil city, 2480m above the sea level.Limnological data about lake is incomplete. This tectonic lake is known to have a unique macro-invertebrate fauna. In order to describe the zoo-benthic community of the lake more completely, the present study was conducted during a period of one year from August 2008 to July 2009 with the exception of 3 months during the 5 months the lake is covered by ice. The benthic assemblage was sampled monthly from four sites and these fauna were found to be very limited with a total of 11 species belonging to 10 families, 10 orders, 7 classes and 3 phyla. Eight species were identified and recorded for the first time in the lake and in Iran.Gammarus fasciatus, Pisidium supinum and Quistadrilus multisetosus were the dominant benthic species representing more than 49, 43 and 5 percent of the total benthic fauna. Almost all benthic species showed the same intra-annual, seasonal and spatial pattern. The highest density was found in station 4, near the outlet, in July. The maximum abundance of total population of rnacro-benthoses in Neor lake was composed of 41872.75 pieces in a sample per square meter in September and the minimum with 28177.08 pieces in March. Dissolved oxygen, temperature and habitat homogeneity seemed to be the main environmental factors affecting community indices in Lake Neor.

This study was carried out to evaluate the effects of dietary lecithin on growth performance and hematological indices in juveniles of Siberian sturgeon (Acipenser baeri). Fish with initial average weight of 32.9±0.3 grams were fed five isoproteic and isolipidic formulated diets with different lecithin levels including 0, 2.5,5,7.5 and 10% in triplicate groups for 8 weeks.Results showed that lecithin supplementation to 7.5% significantly increased some growth indices such as body weight increase (BWI), specific growth rate (SGR), feed conversion ratio (FCR) final weight (Wf), condition factor (CF) and protein efficiency ratio (PER). Also, increasing dietary lecithin to the level of 10% significantly decreased growth indices. According to the results of hematological assays, hemoglobin (Hb) in treatments of 5% and 7.5% in comparison to other treatments had higher value. Hematocrit (Hct) in fish fed with 7.5% lecithin was higher than those fed with 0 and 2.5% lecithin in the diets. Other hematological indices such as WBC, RBC, MCV, MCH and MCHC showed no significant differences among the treatments. In conclusion, the results of this study indicated thatSiberian sturgeon juveniles have a relatively moderate lecithin requirement (between 5 and 7.5 percent of the diet) and these levels of lecithin in diet induces increase of growth performance and improves health status of this species.

Barbus sp. fish samples were collected during November 2007 to October 2008 from five landing stations in Karoon River: Gotvand, Shoshtar, Molasani, Ahwaz, and Darkhoin.During one year of study, more than 2000 specimens of B. grypus and B. barbulus were measured, mean ±SD length values and maximum and minimum total length for this species were 37.94±8.18, 43.62±10.27, 20-76cm and 20-94cm, respectively. Mean±SD of weight values and maximum and minimum weight for this species were 873.2±1092.45g, 778.59±725.97g, 52-11170g and 52-4675g, respectively. Growth and mortality parameters were calculated forB. grypus and B. barbulus as Loo: 86.64, 132.9 and K: 0.27, 0.17 and t0 0.46, -0.66, M: 0.50, 0.33, F: 1.22, 1.04, Z: 1.72, 2.72, F; 3.31, 3.48, E: 0.71, 0.76, respectively. According to the exploitation coefficient, B. grypus and B. barbulus stocks are overfished; hence we suggest a decrease in exploitation coefficient. Based on results and their comparison with the American Fisheries Society (AFS) indices, these species are classified in moderate to high vulnerable group fishes.

In this research, controlled changes of rainbow trout muscular composition cultured in brackish water (14.1 ppt) and freshwater (4.3ppt) was compared. Some 180 juvenile rainbow trout with a weight of 47.2±0.1 g each were released in 6 polyethylene tanks with a capacity of 1.5m3. During the experiment, water temperature was kept constant. Feeding fish was conducted using common Faradaneh food and considering water temperature and fish biomass.After 126 days, fishes attained around 320±20g of weight, were sampled and taken to laboratory and the amount of protein, fat, ash, minerals and moisture in their muscle tissue were measured. Results showed amount of fat and dry matter in brackish water cultured fishes is less than those cultured in freshwater. The average percentage of protein and minerals in brackish freshwater cultured fishes were significantly different and the average percentage of moisture in brackish water cultured fish was higher than those of the freshwater fish.

In this study, the early development of Barbus sharpeyi larvae was surveyed through morphological changes and measuring total length, standard length, head length, thickness of larvae, eye diameter and snout length. The initial period of the larval life can be divided into 2 phases: endogenous and exogenous food sources. During the first three days of the larvae development, there was a gradual yolk sac reduction until its complete absorption at the end of third day, indicating the necessity of exogenous feeding. From the fourth to eleventh day, the final development of the heart, gill, air bladder, fins and intestine were observed. Total length of newly hatched larvae was 6.26mm and total length of fifteen days larvae was 8.35mm. The larval development of Barbus sharpeyi was similar to other Barbus species.