نشریه علوم و فنون شیلات
سال دوم شماره 1 (پیاپی 2، بهار 1392)

Fish fauna at three stations along the Gamasiab River, Kermanshah Province, were investigated for 9 months. Samples were caught using electroshocker and cast net of 1.5 cm mesh size and had their 20 morphometric and 10 meristic characteristics recorded. Twenty three species and subspecies in 14 genera and 5 families were identified, including: minnows (Cyprinidae), sisorid catfishes (Sisoridae), bagrid catfishes (Bagridae), river loaches (Balitoridae) and spiny eels (Mastacembelidae). The highest number of species (18, 78.3%) and genera (10, 71.4%) belonged to Cyprinidae, while 2 species (8.7%) in 1 genus (7.1%) belonged to Balitoridae; the other three families each contained 1 genus and 1 species (4.3%). The lowest species diversity (9 species) was observed in upstream station while the highest diversity (16 species) was in downstream station. Among the identified fish, only Pseudorasbora parva was recognized as exotic and the others were native.

Cell concentrations and growth rate of Dunaliella salina Teodoresco in light intensities of 50 and 150 μmol. photons.m-2.s-1 and temperatures 25 ± 0.5 and 31 ± 0.5 oC (mean ± SD) were studied. The algae was isolated from the Urumieh Lake and cultured in various treatments (n = 12). Algae cells were counted regularly using Thoma counting chamber in 3 replicates on daily basis. The curve of changes in population was plotted. The highest cell concentration (mean ± SD) of 4.8 ± 0.6 × 10 6 cell.ml-1 was observed in light intensity of 150 μmol. photons.m-2.s-1 and temperature 25 ±0.5 oC. The minimum cell concentration (2.8 ± 0.3 × 10 6 cell.ml-1) was observed in light intensity of 50 μmol. photons.m-2.s-1 and temperature 31 ± 0.5 oC. The maximum growth rate (0.38 d-1) was recorded in light intensity of 150 μmol.photon.m-2.s-1 and temperature 25 ± 0.5 oC and the minimum (0.16 d-1) in 50 μmol.photon.m-2.s-1 at temperature 31 ± 0.5 oC Increase in temperature from 25 to 31 oC was found to be correlated with decrease in cell concentration and growth rate in D. salina., but increase in light intensities from 50 to 150 μmol. photons.m-2.s-1 resulted in increase of these factors.

The zooplankton diversity of Helleh estuary, Busheher, Persian Gulf, and its relationship with some characteristics of water quality was investigated. Samples were taken using plankton net (mesh size of 140 µm) with vertical towing from 5 fixed-stations in mid-season from summer 2011 to spring 2012 for one year period. The mean (±SE) of biodiversity indices of Simpson, Shannon-Wiener, and Margalef were, respectively 0.84±0.10, 3.01±0.20, and 1.90±0.10 in summer; 0.63±0.06, 2.20±0.20 and 1.87±0.08 in autumn; 0.73±0.04, 2.22±0.10 and 1.43±0.10 in winter; and 0.87±0.01, 3.44±0.30, and 2.38±0.30 in spring. The seasonal zooplankton similarity based on Jaccard’s and Sørensen’s coefficients were highest (0.61 and 0.76) for summer-autumn, 0.56 and 0.72 for autumn-spring while these value were lowest for winter-autumn (0.27 and 0.43) and spring-winter (0.30 and 0.47). In addition, there were significant correlation between zooplankton density with salinity, dissolved oxygen and chlorophyll a, Simpson and Shannon- Wiener with temperature, and Margalef with pH.

The effects of adding a commercial dietary supplement (Hoplite) containing α and β glucan at 0, 0.5, 1 and 2% levels on the growth performance, body composition and intestinal microbiota of kutum roach, Rutilus frisii kutum, was investigated. The fingerlings (mean weight = 1 ± 0.15 g) were stocked in100 litre PVC tanks (25 individuals per tank) and fed experimental diets 3 times a day to apparent satiation for 60 days at constant water parameters. Biometry was performed every two weeks. At the end of the trial period, growth parameters, body composition and intestinal microbiota were studied. Fish fed 0.5 and 1% Hoplite exhibited highest weight gain, specific growth rate and final body weight, which were significantly different (P

A 4 × 4 factorial design was conducted to quantify the optimum carbohydrate ⁄ lipid ratio to minimize the dietary protein level in growing beluga, Huso huso (initial weight 891.9 ± 33.4 g, mean ± SD). Fish were fed with sixteen experimental diets formulated to contain four protein levels (35, 40, 45 and 50%) and four dietary carbohydrate ⁄ lipid ratios of 0.8, 1.1, 1.4, and 1.7 for 108 days. At the end of trial, there were no significant differences in growth parameters among fish fed with 35, 40 and 45% protein levels. No significant difference in growth parameters and feed efficiency (FE) was also observed when dietary carbohydrate ⁄ lipid ratios decreased from 1.7 to 1.1 within the same energy level (P > 0.05). The highest carcass protein content was observed in fish fed 0.8 and 1.4 carbohydrate to lipid ratio (P

Accumulation of heavy metals (Pb, Cd, Fe, Z, Ni, Cu) in gill, liver and muscle of 30 individuals of greater lizardfish (Saurida tumbil), collected from Hendijan fishing area in April 2012, was assessed. Metals were extracted by digestion method and their levels were measured by atomic absorption spectrophotometr (AAS- model GBC Savanta AA ). Levels of the heavy metals from maximal to minimal were Fe>Zn>Cu>Ni>Pb>Cd. Mean of heavy metals accumulation in gill, liver and muscle were significantly different (P