مجله علمی شیلات ایران
سال سی و یکم شماره 3 (پیاپی 131، امرداد و شهریور 1401)

The effect replacement of various kilka fish oil with canola oil was investigated on growth indices, body composition, and digestive enzymes of Siberian sturgeon (Acipenser baerii). One hundred and eighty fry fish (22.5±2 2.09 g average weight) were fed with four isonitroginus and isolipid diets (44 and 14%) (1: 100% fish oil (FO100), 2: 100 % of canola oil (CO100), 3: 50% fish oil+50% canola oil (CO50+FO50) and 4: 70% fish oil+30% canola oil (FO100+CO30)) for 10 weeks. The mean growth and feed efficiency indices in the fish fed with FO100 and CO100 diets were significantly lower than CO50+FO50 and FO100+CO30 (P<0.05). The changes in the canola oil/fish oil ratio caused changes in the body moisture and ash contents (P<0.05), but had no significant effect on the body protein (P>0.05). The lipase and chymotrypsin levels in the fish fed with CO50+FO50 diet were significantly higher than the fish fed with FO100 and CO100 diet. The results of this study indicated that using a combination of vegetable oil and fish oil in equal proportions has a relatively better effect on the growth indices, body composition, and digestive enzymes of Siberian sturgeon in the growth stage.

In the present study, the physical and chemical factors including optimum temperature and pH, the effect of inhibitors, metal ions, oxidizing agents, and surfactants were assayed on the chymotrypsin activity from beluga (Huso huso) intestine. According to the obtained results, the optimum temperature and pH of the chymotrypsin were recorded at 50°C and 8, respectively, and its activity was extremely decreased at temperature>50°C. Inhibitors including SBTI, TLCK, PMSF, ρ-aminobenzamidine, TPCK, pepstatin A, iodoacetic acid and EDTA significantly inhibited the enzyme activity that PMSF, SBTI and TPCK had a completely inhibition effect on the enzymatic activity (P<0.05). The enzyme activity was significantly increased in the presence of Ca+2 and Mg+2 and decreased by Cu+2, Ba+2, Co+2, Zn+2, Fe+2 and Al+3 (P<0.05). Na+ and K+ did not show any significant effect on the activity of enzyme (P>0.05). The enzymatic activity was significantly increased in presence of surfactants including saponin and sodium cholate and showed a significant decrease in presence of SDS and oxidizing agents like sodium perborate and hydrogen peroxide (P<0.05). Therefore, the results of this study showed that the chymotrypsin activity from beluga intestine had a significant decrease in presence of inhibitors, metal ions (except for Ca+2, Mg+2, K+ and Na+), SDS, sodium perborate and hydrogen peroxide and showed a significant increase in presence of Ca+2 and Mg+2, saponin and sodium cholate that it can be affected the maximum activity of the enzyme in digestive physiology of the beluga.

This study compares the antioxidant activity and phenolic content of extracts of four mollusk species (Oyster rock bivalve; Saccostrea cuculate, cabbage bivalve; Callista umbonella and Molok or cylindrical clam; Solen vagina and edible snail; Ampullaria cuprina) and determine the best mollusk in Qeshm coast. Mollusc species (n=100 for each mollusk) were stored in cold boxes with ice and transferred to the laboratory after collection. The samples were well ground and aqueous, ethanolic (90% ethanol) and hydro-ethanolic (50:50) extracts were prepared from them. The results showed that the highest amount of phenolic content (81.66 mg GAE/g extract), diphenylpicrylhydrazyl (DPPH) antiradical activity (1722.66 µmol Trolex /g extract) and antiradical activity equivalent to Trolex (649.33 µmol Trolex/g) extract) was observed in the ethanolic extract of edible snail. Also, the amount of antioxidant activity was maximum in three methods PMP, 606.66 µmol Trolex, FRAP: (740 µmol iron/ gram of extract and RP: 1.24 in edible snail. Aqueous, ethanolic and hydro-ethanolic extracts of four Mollusca species showed different levels of antioxidant activity in all studied models. In general, ethanolic extract of edible snail showed the best antioxidant activity and phenolic content, which can be considered as rich sources of natural antioxidants for food usage is recommended

The main purpose of this applied research which was carried out by a mixed-method (qualitative + quantitative) approach, was to identify and provide strategies for the development of entrepreneurial ecosystems and start-up businesses in the field of warm-water fish. The statistical population of the research in the qualitative part included 12 experts in entrepreneurship, business, and fisheries, who were selected by snowball sampling, and data were collected from them so the theoretical saturation was achieved. In the quantitative part, the statistical population consisted of experts in the field of fisheries and entrepreneurship from three categories of policymakers, decision-makers, experts, and activists in the field of warm water fish and fisheries operators, of whom 40 interviews and questionnaires were completed through convenience sampling method. In the qualitative part of the research, using the content analysis technique of the interviews, four dimensions of the SWOT model including strengths, weaknesses, opportunities, and threats were identified and it was provided to the respondents in the form of a questionnaire, and the data was collected from them. Based on the results of the quantitative part, strengths in the interior and weaknesses in the exterior environment were dominant. In other words, the development strategies of this ecosystem are within the range of competitive-diversity strategies or adaptive strategies. These strategies try to make the most of the available opportunities by reducing weaknesses. Finally, for the development of entrepreneurship and start-up businesses in the field of warm-water fish, a set of strategies in seven categories of inputs, production and producer, collection/processing, distribution/procurement, financial resources, market/customer, and human resources were proposed.

White spot disease (WSD) is one of the most important diseases in shrimp farming, which has caused a decrease in production and severe economic damage all over the world, including Iran. Mortality caused by this severe disease is very high and reaches 100% within 3 to 10 days from the onset of the disease. According to global statistics, about 300,000 tons of shrimp are lost due to this disease every year in the world. For example, within the years 2004, 2006, 2007, 2015, 2016 and 2019, the outbreak of this disease caused millions of dollar losses to the producers in Iran. Since the VP28 viral protein gene is one of the most important white spot disease virus envelope proteins and plays a role in sticking to and penetrating shrimp cells, and since microalgae is the most important source of food for shrimp in the larval stage, So it can be a suitable host for making  a vaccine. So in this study, samples of shrimp (Penaeus indicus) suspected of white spot disease from Abadan (Khuzestan province) breeding ponds were transferred to the laboratory of Razi Vaccine and Serum Institute of Arak branch and the genomic DNA of the virus was extracted using proteinase K and phenol/chloroform methods. The VP28 gene was proliferated by PCR method, inserted into pCAMBIA1304 vector and finally transferred to Chlorella vulgaris microalgae using electroporation method.

A nursery can improve growth indicators and increase production efficiency. This research compared growth indicators, final harvest weight, and survival rate and feed conversion ratio between nursery and un nursery groups. The number of 819,000   pieces of post larvae 12 with density of 13 pieces per square meter was reared in stocking for 90 days in 9 ponds. The same number of post larves with a density of 4000 pieces per cubic meter was reared in the greenhouse for 30 days. Then it was stocked in 9 ponds with a density of 13 pieces per square meter and they were cultured for 60 days. Biomass was measured every 15 days. Physico -chemical factors of water were recorded every five days. The final weight nursery shrimps was 28.13±0.51 1 and non-nursery shrimps 17.22±0.67. It shows a significant difference (P<0.05). It is probably activated by the compensatory growth of shrimps. The daily growth rate in the nursery group was 0.21±0.01 which was higher compared non nursery group 0.15±0.01 compared to the non-nursery group. It increased significantly. Also, the food conversion rate was significantly reduced. This this study, it can be said that shrimp production using shrimps nursery, in addition to reducing period of the culture with reduces the risk of disease. Also, reducing the food consumption and increasing the weight and quantity of shrimp production would increase the productivity.

The Incheh wetland, with high ecological importance, is located in the north of Aq-Qala (Golestan province). In this study, the surface sediments of the Incheh wetland from 7 stations with a maximum depth of 2.8 m were collected in November 2018 to find the source and determine the amount of heavy metals pollutions in the wetland and calculate the indices of enrichment factor and pollution load. The water environmental parameters, heavy metals, grain size, and total organic matter were measured by portable multi-parameter meter, inductively-coupled plasma mass spectrometry, laser diffraction particle size analyzer, and oven combustion, respectively. The mean of Al and Fe in the sediments were 0.8±0.4 and 1.5±0.6%. Also, the mean of As, Cu, Ni, Pb, Cr, Zn and V in the samples were measured 2.8±4.6, 12.8±3.6, 26.7±6.4, 7.0±2.7, 25.7±7.8, 32.4±16.2 and 28.6±7.1 mg/kg, respectively. In general, in terms of the enrichment factor index, the wetland has low enrichment (1-1.8). In the case that station 5, in terms of Fe (3.7) and As (5.7) had moderate enrichment and moderate to severe enrichment, respectively. In terms of the range of pollution load index (0.46-0.84), all stations were less than 1, so they were not polluted. In general, due to the fact that the amount of nickel and arsenic in all stations and station 5 was higher than the TEL, respectively, it can be concluded that the probability of severe biological effects on most of benthic organisms is low and at the threshold level.

The aim of the present study was to extract, saponify and purify astaxanthin pigment from Haematococcus microalgae (Haematococcus pluvialis) and evaluate its antioxidant activity (DPPH free radical scavenging activity and reduction of ferric ions). For extraction, two single (extraction using acetone solvent or ACE) and combined (extraction by pretreatment with hydrochloric acid and then extraction with acetone or HCl-ACE) methods were used. According to the results, amount of extracted astaxanthin (mg/g) by two methods of acetone (ACE) and hydrochloric acid pretreatment (HCl-ACE), in the extraction, saponification and final purification stages were 4.09 (13.65%), 8.49 (28.30%), 14.59 (48.65%) and 9.49 (31.65%), 13.59 (45.30%) and 25.09 (83.65%), respectively. DPPH free radical inhibition activity of extracted astaxanthin with two ACE and HCl-ACE methods (50 to 300 μg/ml) ranged from 66.25 to 76.26% and 85.39 to 94.06%, respectively. These values for ferric ion reduction power were in the absorption range of 0.61 to 0.75 and 0.78 to 0.92 at the wavelength of 700 nm, respectively. The pigment extracted using the combined method (compared to the single method) had significantly more antioxidant activity (p<0.05). In addition, in both tests, increasing the concentration of astaxanthin up to 100 μg/ml, the trend of antioxidant activity was recorded as increasing and then constant (no significant difference between the concentrations of 200 and 300 μg/ml). Comparison of the antioxidant activity of astaxanthin with synthetic antioxidants showed that the pigment extracted by combination method (at high concentrations) had the activity closer or even more than BHA and BHT. According to the findings, the combined method (acid-acetone) compared to the single method (acetone) can improve the extraction efficiency and antioxidant activity of this pigment. Therefore, the method used for the extraction and purification of astaxanthin potentially affects its extraction efficiency and antioxidant activity, and by choosing the extraction optimum method, the mentioned two indicators can be improved in the pigment.

In this study, the effects of dietary addition of vitamin C, astaxanthin, and lecithin on the fertility ability (percentage of fertilization and eyed-eggs) and activity of SOD, CAT and GPx in the ovarian fluids of Caspian trout (Salmo caspius) were investigated. For this purpose, nine different experimental diets: C0A0L0 (0 mg kg-1 vitamin C, 0 mg kg-1 astaxanthin and 0% soybean lecithin), C300A50L0, C700A100L0, C0A50L6, C300A100L6, C700A0L6, C0A100L9, C300A0L9, and C700A50L9 were formulated and the broodstocks (2.51±0.05 kg) were fed for four months. After sexual maturation and spawning, the ovarian fluids were isolated to measure the activity of antioxidant enzymes (AAE) and to evaluate its fertilization ability. The sperm mixture of 9 male broodstocks was used to measure fertilization ability. The results showed an increase in the relative fecundity and AAE in ovarian fluid. The lowest relative fecundity (680±38 eggs per Kg of broodstock weight) and SOD, CAT, and GPx (816.33±67.60 u/ml, 1.29±0.40 nmol/min/ml and 1.06±0.08 nmol/min/ml, respectively) were observed in C0A0L0 which significantly different from other treatments (p<0.05). The highest percentage of fertilization and eyed-eggs were obtained in C300A100L6 (91.66±5.13% and 87.63±1.3%, respectively) which significantly different from the freshwater treatment (77.66±4.16% and 47.86±5.1%, respectively; p<0.05). According to the results of this research, adding of 300 mg kg-1 vitamin C with 100 mg kg-1 astaxanthin and 6% lecithin can increase the relative fecundity, fertilization ability and AAE in ovarian fluids of Caspian brown trout.

Herpesvirus type 3 (CyHV-3) is the main cause of contagious koi herpesvirus infectious (KHVD) in common carp and koi worldwide. For this purpose, 60 pieces of common carp from farms with losses and farms from Khuzestan province that reported losses in the last few years were sampled during 2017 to 2021 for detection of Koi herpes virus disease by molecular method. In order to increase the virus load in gill and kidney tissues, three gills and kidney samples were separately mixed together for each three fish. DNA extraction from the tissue was performed using the commercial kit of Raha Zist Padtan Company according to the instructions. Afterward, Nested PCR test was performed using Amplicon master mix and polymerase gene primers. The results of the Nested PCR showed that 3 samples (two gill samples and one kidney tissue sample) out of 40 mixed samples tested had 339 kbp band and were considered as positive samples. Sequencing of PCR products and preliminary Blast analysis showed that the sequence of one of the positive samples was similar to the CyHV-3. The results of the alignment of the nucleotide rows and the phylogeny tree of this sequence confirmed Koi herpesvirus and it was registered in the World Gene Bank with the accession number of LC713276.