نشریه پژوهش های ماهی شناسی کاربردی
سال چهارم شماره 3 (پاییز 1395)

Growth and mortality parameters for Kawakawa (Euthynnusaffinis Cantor, 1849)were studied using the length frequency composition and biometry of 13716 individuals in Hormozgan province waters in 2013. Length range and mean length range of this species were obtained as 22-85 cm and 59.36 cm, respectively. ELEFFAN I method in FISAT program were used for data analyses.Growth parameters were estimated aslength infinity (L∞) =88.2 cm, growth rate (K) =0.51 year-1 and the age at the length 0 (t0) =-0.23. Overall,eight cohorts were distinguished for kawakawa and maximum recruitment pattern was obtained as 14.48%in August.Total mortalityestimation was found to be Z= 1.87 year-1using catch curve.Natural and mortality coefficients were estimated using the Pauly's formula which resulted in M= 0.64 year-1and F=1.23 year-1, respectively.Exploitation rate (E) was calculated as 0.65 indicating that kawakawa was fully exploited in Hormozgan provincewaters.

Golden grey mullet, Liza aurata, is a non-endemic species with high commercial value in the Caspian Sea. This species showed sever mortality during recent years due to viral nervous necrosis. In the present study, six microsatellite loci (Mcs16Em, Mcs15Am, Muso10, Muso19, Muso22 and Muso27) were used to assess and compare the genetic structure of golden grey mullet in Gharesou and Gomishan regions (28 samples for each region) as well as dead samples from Gharesou region (28 samples). The polymorphism was observed in all loci. In the study of genetic diversity indices, the mean number of alleles and observed heterozygosity were obtained as 14.33 and 0.82, respectively. In addition, no significant difference of allelic diversity and heterozygosity was also observed between studied samples. 10 out of 18 tests showed significant deviation from Hardy-Weinberg equilibrium. The average amounts of inbreeding (Fis), genetic differentiation (Fst) and gene flow (Nm) indices were obtained as 0.07, 0.033 and 8.40, respectively. Furthermore, the lowest genetic distance and the highest genetic similarity were observed among the samples of Gomishan and Gharesou in that according to UPGMA dendrogram based on genetic distance, the samples from Gharesou and Gomishan were considered as a separate group from the dead samples.

In order to determine the catch composition of trawl in Chabahar region (Sistan and Baluchistan coastlines), the present study was carried out in Chabahar, Konarak and Pozm ports in June 2016. 23 species belonging to 15 families were caught and identified after seven times trawling. Mean while, the maximum composition catch (63%) was observed in Cutlass fish (Trichiurus lepturus). This is while, the minimum composition catch (0.05%) belonged to Areolate Grouper (Epinephelus areolatus), Gulf torpedo (Torpedo sinuspersici), Orange-spotted grouper (Epinephelus coioides), Gold bandedjob fish (Pristipomoides multidens) and Giant catfish (Netuma thalassina). The maximumlength-frequency of Cutlass fishwas observed in the length class of 77.5 – 88.5 cm. Based on the biodiversity and indices analysis regarding the caught fish, Simpson and Shannon indices were estimated as 0.692 and 2.459, respectively. In addition, natural richness was 29.9 and evenness was calculated as 0.185 using Camargo equation.

Continuous droughts, decline of water-wellquality and their salinity increaseare the future bottlenecks in the culture of Sistan’s loach (Schizithorax zarudnyi). This fishes an endemic species in Sistan region. Effects of different degrees of salinity stress (1, 3, 6, 9 and 12 ppt) on the growth rate; some of bloodbiochemical parameters (such as glucose, sodium, potassium, calcium and total protein) and cortisol hormone level inthis species wereevaluated in order to obtain the appropriate conditions for growth and culture. For this purpose, 255 individualswith total length of 14.49±0.387 cm and mean weight of 24.89±1.41 g were cultured for 30 days.Thegrowth rate was determined atday (D)1, D15 and D30 and the levels of cortisol andbiochemical parameters of the blood were measuredat the end of the experimentalperiod. The growth rate decreased withsalinity increase compared to the control treatment (1 ppt salinity) in that growth rate was negative in treatments with3, 6 and specially 9 and 12 ppt salinitiesbut no mortalities were observed in all treatments. The levels of cortisol hormone and glucose increased with salinity increases. The highest and lowest levels of cortisol and glucose were observed for the treatmentwith12 pptsalinity and control treatment, respectively (p

In order to improve aquaculture in the future, management of aquatics breeding seems to be necessary. According to the different limitative parameters of white fish natural breeding (Rutilus frisii kutum), it is impossible to restock this species through natural breeding. In order to evaluate the effect of Ovaprim (Dampridon䨉턝), Ovafact (Dopamin Antagonistᩴ) and Pitutary extract on artificial reproduction of white fish, 50 individual female brood stocks were caught from Sefidrood River during breeding migration time. They were then transferred to Shahid Ansari fish breeding center (Rasht, Iran). The fish were divided into six treatment groups: a control group (injected fish with physiology saline), injected fish with Ovaprim (10, 20 and 30 µg/ Kg body weight), injected fish with Ovafact (5 and 10 µg/ Kg body weight) and injected fish with pituitary extract of Common carp (3 mg/kg body weight). Based on the obtained results, the maximum and minimum fertilization rate was observed for injected white fish with Ovaprim (20 μg/kg body weight) and pituitary extract, respectively. The maximum rate of brood stock response was obtained for fish injected with Ovafact (10 µg/ Kg body weight) and Ovaprim (20 µg/ Kg body weight). However, its minimum rate was belonged to the brood stocks injected with pituitary extract and Ovaprim (30 µg/ Kg body weight). The maximum and minimum maturity time was found in white fish brood stock injected with 10 µg/ Kg body weight of Ovaprim (45± 2 hours after hormone injection) and 10 µg/ Kg body weight of Ovafact (40.25± 2 hours after hormone injection), respectively. The maximum and minimum degree-hour of ovulation was also recorded for fish injected with Ovaprim (10 μg/kg body weight), and Ovafact (10 μg/kg body weight), respectively. Furthermore, the maximum and minimum rate of hatching was reported for fish injected with Ovaprim (10 μg/kg body weight), and pituitary extract, respectively. The maximum and minimum degree-hour of hatching was obtained for fish injected with Ovaprim (10 μg/kg body weight) and Ovafact (10 μg/kg body weight), respectively. Due to of the high effect of Ovaprim hormone on white fish ovulation rate reported in this study and more availability and lower cost of this hormone compared to Ovafact and pituitary, it is suggested to use Ovaprim hormone aquaculture studies.

The present study was designed and conducted in order to evaluate effects of different dietary betaine supplementation levels (0.5, 1, 1.5, 2 and 2.5 % Betaine kg-1 diet) on the growth rate, carcass compositions and some haematological-biochemical parameters of the blood serum in beluga, Huso huso to do so, 150 individuals (4.6±0.61 g) were randomely distributed into 15 fiberglass tanks (500 liter, 10 individuals in each tank). Three replicates were considered for each treatment and the fish were fed by one of five experimental diets for 12 weeks. Final weight, specific growth index, protein efficiency ratio, condition factor (CF) and feed conversion ratio (FCR) were significantly more favourable in the fish fed by diets containing 1.5 -2 % Betaine kg-1 diet compared to those fed by diets containing 0.5 % Betaine kg-1 diet at the end of experimental period. The higest growth performance and nutrient efficiency were also observed in the fish fed by diets containing 1.5-2 % Betaine kg-1 diet. The level of protein in the carcass was significantly increased as a result of adding Betaine to the fish diet. The mean number of white blood cells (WBC), activity of liver enzymes such as Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) were significantly lower in the fish fed by diet containing 1.5 and 2 % Betaine kg-1 diet compared to those fed by 0.5 % Betaine kg-1 diet. Consequently, it is suggested to use 1/5-2% Betaine in the food diet of juvenile beluga sinorder to obtain the maximum growth rate, optimized carcass composion, haematologicalparameters.

Five hundred and ninety two Siberian sturgeon (A. baerii) fingerlings (average weight, 11.1±0.9 g) were randomly distributed in 16 tanks (150 L) at a density of 35 fish per tank and fed different treatments (Control, degrading bacteria, 2% PHB, degrading bacteria 2%PHB) for 60 days. At the end of the experiment, the results indicated that the fish fed PHB or bacteria treatments had low midgut pH and the lowest pH was observed in PHB treatment. Also PHB significantly decreased hindgut pH then the others and the lowest hindgut pH was seen in PHB treatment (p

The spread of Saprolegnia fungus throughout the incubation period and the prohibition use of chemicals such as Malachite Green, necessitate the substitution of antifungal compounds with high efficiency and minimum environmental side effects. Garlic (Allium sativum) is a plant whose antifungal and antimicrobial properties have been frequently studied. Therefore, the aims of the present study were to assess the antifungal effects of aqueous, ethanol and methanol extracts of garlic on Saprolegnia fungus, determine its minimum inhibitory concentration for the fungus growth and compare the minimum inhibitory level of the garlic extracts with Malachite green and Bronopol. Saprolegnia fungus was isolated, purified and identified from the infected eggs. Ethanolic, methanolic and aqueous garlic extracts were prepared. The inhibitory effects of different concentrations (0.3, 0.5, 3, 50 and 100 mg/ ml) of these extracts were tested 48 hours after fungus growth using wells method. Results showed that inhibitory level of all tested extracts on the growth of Saprolegnia fungus at day (D) 1 and D2 was significantly different from D3. The ethanolic extract of the garlic with 3 mg/ml concentration showed the highest inhibitory effect on the Saprolegnia fungus growth rate compared to Malachite green and Bronopol. The level of MIC for aqueous, ethanolic and methanolic extract was obtained as 0.3 mg/ml. Consequently, garlic extract possesses antifungal effects and it can be used as an antifungal in the aquaculture industry due to its herbal origin and having no side effects on aquatics and consumers.