Iranian Scientific Fisheries Journal
Year:2011 | Volume:20 | Issue:1 (74)|Papers Count:19

To assess the effects of dietary nucleotide on structure of pyloric caeca in Salmo trutta caspius, 315 juvenile fish with average weight of 12.26g (average length 11.12cm) were fed with dietary nucleotide (NT) and a control diet for 8 weeks (0.25% NT, 0.5% NT and 0% as control). To investigate the changes of pyloric caeca structure, 6 fish specimens from each treatment fixed into Bouin solution for histological examinations. Then, the sample was placed in paraffin, and 4mm sections of samples were provided and after coloration were investigated for histological features. The investigation demonstrated that both NT-supplemented diets had significant effects (P<0.05) on thickness of enterocyte, villi length, number of enterocyte cell and thickness of pyloric caeca muscle. However, between the two treated groups, changes of enterocyte and sub mucosa, length and number of villi were non-significant (P>0.05). However, the group receiving 0.25% NT showed more positive effects on enterocyte cell number and thickness of muscle layer compared with those treated with 0.5% NT.

Morpho-cytological patterns of juvenile Acipenser persicus on basis of structure, size and distribution of kidney nephrons were studied. Sampling of head, body and caudal parts of the kidney in the fish aged 1 and 2 years were carried out (3 specimens of each age). Area, length and small diameter of nephron cells were measured by light microscope and Biocome Visolab software. We observed the kidney of A. persicus consisting of: Glomeruls, Bowman's capsule, Proximal, Distal and Collecting tubule. The statistical analyzes showed no significant difference in the area, length and small diameter between the two ages. Furthermore, the results showed that the average area in 1 and 2 year old fish were 4004.28±2486.63 and 4614.64±1261.69 mm in proximal cells, 2529.75±1015.51 and 4747.33±1676.03 mm in distal cells, 2220.98±1668.87 and 3253.48±1747.25 mm in collecting tubules, 4692.37±1739.79 and 9355.37±2073.92 mm in Glomeruls, 6768.23±1640.54 and 129210.07±1775.76 mm in Bowman's capsule, respectively. The average length and small diameter in 1 and 2 years old fish were 84.75±24.99, 53.52±14.03 and 82.76±7.46, 66.00±7.37 mm in proximal cells, 72.98±16.28, 51.10±15.00 and 77.95±9.43, 64.57±8.34 mm in distal cells, 60.52±13.69, 49.02±12.60 and 66.40±12.21, 57.40±14.20 mm in collecting tubules, 94.70±16.97, 72.78±12.75 and 129.04±23.59, 96.60±18.88 mm in Glomerules, 120.99±14.86, 80.77±9.78 and 144.76±21.12, 107.56±21.53 mm in Bowman's capsule, respectively. In all cases, no significant differences were found between measured cell of the 1 and 2 year old fish (P>0.05). Also, the modeling showed the kidney of A. persicus was Y shaped in which the distribution of different cells is not homogenous in all sections of the kidney.

The likely effects of sodium alginate edible coating on the quality of dressed kilka fish in the frozen storage was investigated. Sodium alginate edible coating was prepared in four concentrations (0.25, 0.75, 1.25, and 1.75%). Then, dressed kilka fish were coated with sodium alginate for l h, packed in polyethylene dishes with cellophane blanket and stored at -18oC. The amount of hem Iron, pH, percent lipid and organoleptic characteristics (odor, color) were assessed within 0, 1, 2, 3 and 4 months (sample size: 125 packs of 250g). Results showed a significant difference between the mean hem iron and percent lipid and increase in sodium alginate concentration (P<0.05). The pH of samples showed no significant difference (P>0.05) with different levels of coating. Organoleptic results showed that the mean color and odor value of the samples were affected significantly by different levels of coating (P<0.05). Use of sodium alginate edible coating to protect hem iron and improve organoleptic properties can increase the quality of kilka in frozen storage up to 4 months.

Metals concentrations were studied in dominant seaweeds and their adjacent sediments in Bandar Abbas and Bandar Lengeh tidal areas. The status of selected heavy metals (Ni, Cd, Pb, Cu) was determined in sediments and 15 dominant seaweed species including 4 species of Chlorophyta, 4 species of Phaeophyta and 7 species of Rhodophyta. Samples of seaweed and sediment were collected seasonally during November 2007 to August 2008 from intertidal regions of nine sites along the Bandar Abbas and Bandar Lengeh coasts. Powdered samples of sediments and seaweed were digested and analyzed using Atomic Absorption Spectrophotometer (A.A.S). Concentrations of Cu, Pb, Cd, and Ni were 5.24, 20.44, 5.40 and 33.83 mg/g-1 dry wt. in sediments. Concentration of these metals in mg/g-1 dry weight in Chlorophyta were 11.11, 25.79, 4.76 and 46.57, in Phaeophyta were 9.18, 17.68, 4.82 and 36.65, and in Rhadophyta were 9.80, 21.03, 4.96 and 50.43, respectively. The marine seaweed species collected during all seasons and sites in Bandar Abbas and Bandar Lengeh were identified as Entromorpha compressa and Padina pavonica, respectively.

Cultured fish are presented in various sizes and prices in market. The present study aimed to investigate the proportion of nutritional value and price of various weight groups of bighead (Hypophthalmichthys nobilis) and to offer two indices for comparing nutritional value in proportion with fish prices. For this purpose, bighead specimens were prepared in market sizes and their dry matter, lipid, protein and ash content and fillet yield were determined. Then, the proportion of nutritional and financial value (NP) and justified price difference based on dry matter content (PDdm) were calculated for each weight group. The results showed that the light weight group has a higher NP index for dry matter, protein, ash and energy than medium and heavy weight group. The NP index was the same between medium and heavy groups. While the price difference between light weight and two other weight groups is more than calculated PDdm index, the light weight group is a proper choice for purchase.

This study was conducted in vitro to assess lethality, LC50 and the possibility of bioaccumulation of cadmium in various life stages of Artemia urmiana. Artemia is highly used in aquaculture; hence the response of the organisms to pollutants, such as cadmium regarding the increase in environmental pollution is of high importance. This experiment was performed in Faculty of Marine science and Technology, Islamic Azad University and Atomic Energy Organization of Iran in 2009. In the first stage, smaller than 1day naupliis were exposed to 10 different concentrations from 0 to 250mg/l Cd. LC50 of Cd in 24h of A. urmiana exposure was 189.33mg/L. Next, the accumulations of Cd in 5, 10, 15 and 20mg/l Cd were examined in 1, 5, 11 and 17 days of Artemia urmiana life. The results showed that Artemia urmiana has the ability of accumulation of cadmium and the accumulation level depends upon the concentration of the cadmium in the environment as well as different living periods of Artemia. We found that increasing the concentration of cadmium in the environment increases its accumulation in Artemia. There was a significant difference in accumulation of Cd between 5mg/l Cd (0.267ppm) and 20mg/l Cd (0.364ppm) in the first day of A. urmiana life (P<0.05). In all treatments of the 11 day Artemia, bioaccumulations of Cd increased with increasing of cadmium concentration. Maximum accumulation of Cd was in 20mg/l Cd in the 11 day Artemia. Results showed that although A. urmiana is resistant to Cd, however in 250mg/l, cadmium has significant toxic effects on Artemia survival (3.33%).

Neogobius caspius is a small benthic fish, native to the Caspian Sea. The fish is highly important as it comprises the main food item of the Caspian Sturgeons. The genetic diversity of N. caspius populations in the Caspian Sea was studied using microsatellite technique. In the study, 115 specimens of N. caspius from two regions (Turkmen Bandar and Anzali Bandar) in south Caspian Sea were collected. DNA was extracted using 12 pairs of microstellite primers for which polymerase chain reaction (PCR) was conducted. DNA bands were analyzed using UVdoct and GenAlex software package. Out of 12 microsatellite primers, 11 loci were produced, of which 9 were polymorphic, 2 monomorphic and one showed smear. The average observed and expected hetrozygosity was 0.749 and 0.638, respectively. Significant genetic differences between the two regions were observed (P£0.01). Deviations from Hardy-Weinberg equilibrium were in all specimens. These results indicate that at least two populations of N. caspius exist in the south Caspian Sea.

The growth of organisms on seven different artificial reef structures was surveyed from 2004-2006 in Hormuzgan offshore waters (Bandar Lengeh area). The organisms consisted of 12 groups the main of which included Barnacle (Megabalanus tintinnabulum), Sponges with five families and Tunicates. The highest density was observed in 2005, amounting to some 409.224g wet weight on each structure. However, a decrease was observed afterwards in the total mass of aquatics living on the structures. Some organisms such as crabs, polychaets, bivalves and fish larvae showed an increasing in size in the first year. Bivalves showed a decreasing trend in density but otherwise an increasing trend in size over time. Artificial shape of the reefs was not effective on the total density of the organisms living on the structures. Total density of live organisms on different parts of the artificial reefs (surface, middle and bottom) was not statistically significant (P>0.05). Numbers of crabs on mixed artificial reefs were higher than the other artificial reefs. This was also the same for barnacles.

The toxic effects of water soluble fraction (WSF) of crude oil on the gills of juvenile kutum roach, Rutilus frisii kutum, were investigated. The juvenile (1-2g) kutum roach were collected in summer 2008 from the Kolmeh Hatchery Center, Golestan province, and acclimatized to laboratory conditions through keeping them in a 300 liter tank with de-chlorinated water for a minimum of 8 days. Six different types of WSF concentrations were made to obtain LC5096h including 27, 29.25, 31.5, 33.75, 36 and 38.25ppm. Then, 10 fingerlings of R. frisii kutum were exposed to the WSF concentrations, for 96 hours. Considering mortality rate of the juveniles in 96 hours and using Probit value statistical analysis, LC5096h was obtained at 33.95ppm. Two different concentrations (0.1 LC50 and LC50) of WSF were prepared for further assessments and after 24 and 96h of exposure, 3 individual fish were collected from each aquarium for histopathological studies. The gill sections with 3 micron thickness were prepared, stained using H & E, and examined by light microscope. General damages after observation included: Epithelial lifting, congestion in filament and lamellae, clubbing, fusion, hypertrophy of epithelial cells of lamellae, different levels of hyperplasia between lamella and aneurysms. Pathological studies showed that the WSF of crude oil causes serious damage in gills of juvenile R. frisii kutum, leads to malfunction of this organ which will harm homeostasis of the fish.

Clinoptilolite efficiency on absorption of ammonia in rainbow trout was studied. The fish specimens weighted 9.5-21g and were exposed to four different concentrations of total ammonia as N-NH4 including: 10, I5, 20, and .25mg/l. A group of 13 fish was considered as control. Lethal concentration was determined after 24 hours. Under stable temperature and pH conditions (T=16±1oC, pH=7.7±1), the lethal concentration of total N-NH4 was 25mg/l (as ionized N-NH3=0.44mg/l based on temperature and pH). In lethal concentrations of ammonia, different amounts of zeolite (2, 5, 10, 13 and 15g/l) were used. Application of 15g/l of the zeolite prevented mortalities in the fish. A significant difference was found in reduction of total ammonia and total hardness through application of zeolite after 24 hours (P<0.01). The maximum mortalities occurred in early time of experiment. The histopathological lesions of gill, kidney and liver were studied.

The effects of two levels of vegetable oils on structure of pyloric caeca were studied in Caspian Sea salmon juveniles (Salmo trutta caspius). The levels of dietary vegetable oils comprised of 10% and 20% of total diet and in each level 85% canola and 15% soybean was used. In these experiments, 270 juveniles each weighing 10g were selected, 90 were allocated to the two treatments and 30 for replications and also a control group was considered and fed with commercial food. The juvenile fish were cultured for 8 weeks, fed two times daily and then 6 samples from each treated group were fixed for histological studies. Histological examination under light microscope and using Hematoxylin-Eosin staining was conducted. Results showed that 20% dietary vegetable oil as compared with 10% significantly increased the area and number of pyloric caeca entrocytes. The effect of 20% dietary vegetable oil on the area and number of pyloric caeca entrocytes as compared to the commercial food was not significant. Gap in lumen ceacum was not significant between the two treatments as the lumen diameter increased with increase in dietary oil. We conclude that dietary vegetable oil content at 20% level can increase the area and number of pyloric caeca entrocytes which leads to increase in absorption of nutrients and of higher osmoregulation ability.

Stock assessment of edible bivalve, Solen brevis was carried out in Bushehr shoreline areas (50o 21’ E - 29o 41’ N to 52o 41’ E - 27o 17’ N) throughout the period of September 2008 till September 2009. The objectives of this study were identifying the distribution, and estimating the abundance, growth parameters and natural mortality of the bivalve. Solen specimens were collected monthly in Bupatil area and from three other areas at low tide. On each transect one or two quadrats (0.25m2) were placed at random. To estimate the stock abundance, the mean number of shells in each quadrat was regarded as an estimate of stock mean. Length frequency was used to estimate growth and natural mortality parameters. Data analysis was conducted with the most recent version of LFDA statistical software.The main distribution areas for live edible bivalve, Solen brevis, were located at Bupatil, Gasir, Kaloo, Piazi and Bordekhoon. The mean (±SD) abundance in Bupatil was estimated at 3.25±1.1 shells per quadrat with a maximum peak in October and minimum in August. The estimated growth parameters of this species was, K=0.7year-1, L¥=120 mm and t0=-0.35. Natural mortality rate (M) was estimated at 0.26 and the calculated maximum age (Tmax) was 54 months.

A four-week trial was conducted to evaluate the effects of different levels of dietary Betaine on growth, survival and resistance to salinity (35ppt), temperature (24oC), hypoxia and high and low pH stresses in rainbow trout (Oncorhynchus mykiss). Four levels of Betaine as 0 (control), 0.4% (B0.4), 0.8% (B0.8) and 1.2% (B1.2) were used with three replicates. Forty fish (0.67±0.15g) were stocked in each replicate and fed at 4-4.5% of body weight, five times daily. Results showed that there were significant differences in growth, survival, NPU, PER and FCR between B0.4, B1.2 and control diet (P<0.05). Carcass analysis showed that there was higher protein in the carcass of fish fed with diet B0.4 compared to control and B1.2 diet. There were no significant differences in carcass protein content between B0.4 and B0.8. Also, no significant differences were found in carcass crude fat, ash and dry matter among different treatments (P>0.05). Resistances to high and low pH (10.8 & 3.8) and to high temperature (24oC) were significantly better in fish fed with Betaine containing diets compared to the control diet. Resistance to high salinity in B0.4 was significantly better than the control diet and resistance to hypoxia in diet B0.8 was significantly better than the control (P<0.05). The results showed that dietary supplementation of Betaine (0.4%) have positive effects on growth factors, survival, body composition and resistance to environmental stresses in rainbow trout.

Lanternfish (Benthosema pterptum) is one of the most important fish species in the Oman Sea. We randomly sampled 300 myctophids from different depths in spring and winter 2009 in the Oman Sea using mid-water trawls. Male to female sex ratio was 0.36:0.64. The thin sections (60-80 mm) of sagitta otoliths of the fish were prepared using polishing method. These sections showed that increment growth rings of lanternfish otolith are formed daily and the age condition is distinguishable on a daily basis. We found the life span of the species to be short (with a maximum of 349 micro-increments counted) and probably less than a year. The relationship between standard length (SL) and daily growth increment (D) was expressed as the linear equation: SL=0.87D+12.37 (R2=0.97). The relationship between lanternfish weight (W) and daily growth increment (D) was expressed as power equation: W=0.00003D1.754 (R2=0.95). Furthermore, morphometrical characteristics of otolith including otolith weight and length and daily growth increment relationships were expressed as linear equation (R2=0.96 and R2=0.83). The results showed that lanternfish growth rate were in the range 0.241mm/d-1 to 0.138mm/d-1 and decreased by body size and age in this range.

A one-year study (May 2007-April 2008) was undertaken to identify the echinoid species of intertidal sandy and rocky shores of the Qeshm Island. An intertidal sandy location and a rocky shore were surveyed in southern coasts of Qeshm Island, in northern Persian Gulf. Specimens were monthly collected along two 30m wide by 30-60m long (according to the tidal range) transects located approximately 300m apart, perpendicular to the sea, in each shore. Sampling was accomplished using 0.25m2 quadrat along each transect in the rocky shore, and by walking along nine 10x10-30m transects along each transect in the sandy shore.Three species of echinoids, belonging to 3 families were identified including: Clypeaster reticulatus, Diadema setosumand Echinometra mathciei. Identifications were verified by National Museum of Natural Science, Taiwan. While Clypeaster reticulatus belongs to sandy habitats, none of the identified species were observed in sandy location.

The potential effects of stocking densities (1, 2, 4, 6 and 8kg/m-2) of Beluga (Huso huso) was investigated on water quality and growth factors of the fish. Feed was offered three times daily using a commercial diet to the juvenile fish at the average initial weight of 93.13±1.04g (±SE) for a period of 8 weeks. The final biomass was 4.0, 6.5, 11.0, 14.5, 17.1kg/m-2 from the lowest to the highest densities, respectively. At the termination of the experiment, the mean weight reached 362.4±6.9, 319.7±2.1, 267±9.2, 242.1±6.2 and 211.1±4.1 in densities of 1 to 8kg/m-2, respectively. Results of the present study showed that growth parameters, including: Final weight (W), body weight daily (BWD), weight gain (WG), condition factor (CF) and feed efficiency (FE) had significant differences among the treatments (P<0.05). Water quality indices including nitrite (N02), ammonia (NH3), nitrate (N03) and dissolved oxygen (DO) showed significant differences among the treatments affected by different densities, while other water quality parameters including temperature and pH showed no significant difference (P>0.05). Results showed that stocking densities have major effects on water quality and growth indices of Beluga juveniles.