Iranian Scientific Fisheries Journal
Year:2016 | Volume:24 | Issue:4|Papers Count:17

Regarding to the tight association between aquatic hypoxia and heavy metal contaminations in one hand and the role of both parameters on fish respiration, metabolism of carp could be assessed under single and mutual exposures to hypoxia and cadmium. Following measuring LC50-96h of cadmium (43.679 mg/l) for this species, 80 common carp were exposed to 10 different treatments, including control, acute (43.68 mg/l), sub-lethal (21.84 mg/l) and chronic (4.37 mg/l) cadmium as well as hypoxia for immediately (20% of saturation), 24h (40%) and 7 days (60%), and joint exposure of each similar treatment. By using of respirometer technique, we measured oxygen consumption rate in different time spans to calculate each individual standard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic scope (AS), factorial aerobic scope (FAS) and critical oxygen tension (PCrit). Obtained data show that acute and sub-lethal cadmium treatments led to significant (P<0.05) increases in all metabolic indices in comparison with control group whilst the MMR and AS have been reduced (P<0.05) following hypoxia treatments. Combined treatments of hypoxia and cadmium led to reduce SMR and PCrit in all treatments and MMR, AS and FAS only in acute and sub-lethal treatments. In overall, hypoxia can act as a limiting stressor in carp while cadmium can account as a loading stressor.

Fishing water sources and aquatic breeding, is of great importance for the region and the country's economy. Professional fishing and fish farming, employment and income opportunities for people in different parts of the country has created.Articles 115 and 33 of the third and fourth five year economic, social and cultural development plan emphasize on the elimination of non-tariff barriers and replacement of tariff equivalents.So the methods which can be used for quantification of non-tariff barriers should be identified and compared. In this paper tariff and non-tariff barriers of fishery products within time period 2007-2014 are analyzed by price wedge method. The price wedge method yield a tariff –equivalent estimate of technical barriers to trade. The main findings reveal superiority of price-wedge method.Also majority of products under study such as ornamental fish, fish breeding and trout show an increasing tend in terms of tariff equivalents.

The sensory attributes, chemical indices, microbial load and fatty acid composition of Silver carp were investigated as affected by thermal drying. The samples were dried at 60oC for 4-24 h using a laboratory dryer, and stored at 4oC. Temperature and time were recorded until moisture reduced to 35%. The products were packed under atmospheric and vacuum conditions. The results showed that there were no effects on sensory attributes, microbial load, pH and FFA. However drying significantly (p<0.05) affected TVB-N (4.26 to 18.30 mg/100g), PV (0.46 to 2.36 meqO2/Kg) and TBA (0.032 to 0.105 mgMDA/Kg). Mold and yeast counts were significantly (p<0.05) decreased (1 to 0.50 Log cfu/g) after process. Saturated fatty acids (30.66 to 34.29 g/100g) and & omega; -6 fatty acids (5.57 to 7.13 g/100g) were significantly (p<0.05) increased due to drying, but in contrast unsaturated fatty acids (54.62 to 50.56 g/100g), & omega; -3 (16.10 to 7.37 g/100g) and Polyunsaturated fatty acids (21.76 to 14.50 g/100g) were significantly (p<0.05) decreased. However, all of qualitative parameters and sensory attributes were changed during storage. Microbial load of vacuum-packed dried fish were lower than atmospheric samples; qua bacteria and mold-yeast counts were significantly (p<0.05) increased from 2.05 to 3.26 and 1.06 to 3.52 Log cfu/g, respectively. The results showed that vacuum packaging did not affect sensory attributes. Both dried products had acceptable quality during 30 days of storage but the vacuum-packed were better than atmospheric packed.

The kutum (Rutilus kutum) is one of the most important and commercial species of the bony fishes and comprises up to 70% of catch composition in Iranian waters of the Caspian Sea. Catch and effort data of the beach seine fishing cooperatives as well as the distribution and important species index (ISI) in the fishing areas were assessed between 1996 and 2011. The kutum had a wide distribution in the Iranian waters of the Caspian Sea during the study period. The minimum proportion in catch, distribution and ISI for kutum were observed in the east coast of the Golestan province, while the maximum values were observed in the Guilan province (before 2006) and Babolsar fishing area (from 2007 to 2011). The ISI was higher between 2006 and 2011 than the previous years, and the maximum level of this index was obtained 78 in 2008. The CPUE increased from 1996 to 2011. The maximum CPUE between 1996 and 1999 was in the range of 220.3 to 384.5 kg/haul (observed in Astara fishing area), while between 2008 and 2011 the maximum CPUE was in the range of 364.3 to 566.3 kg/haul (observed in Babolsar fishing area). In general, distribution and ISI of kutum between 1996 and 2011 were higher in the Mazandaran province than the other fishing areas.

Nisin is a natural antimicrobial and has inhibitory effect on the pathogens and spoilage organisms. The purpose of this study was to evaluate the effects of nisin (0.15%) and sodium acetate (1%) individually and in combination on shelf life of vacuumed trout (whole fish without viscera) in refrigerated temperature. Physical and chemical parameters including pH, peroxide value, thiobarbituric acid and total volatile nitrogen bases and bacterial factors such as TVC, PTC and LAB were examined. These parameters were measured at an interval of 4 days for 16 days. Results showed that the PV, TBA, TVN and pH in combination of sodium acetate and nisin Z treatments were significantly lower compared to control (no preservatives) (P<0.05). Treatments with sodium acetate and nisin Z (individual) were followed after combination treatment. It seems that a combination of natural and chemical preservatives significantly increases shelf life of rainbow trout.

The solution that can also provide nutrients to support the growth of aquatic organisms, increased health, resistance to stress and pathogens are using dietary probiotics, prebiotics and synbiotic in aquatic food. This study aimed to evaluate the performance of commercial and non-commercial synbiotic on hematologic and biochemical parameters of western white shrimp hemolymph was done in 4 treatments including S1 (commercial synbiotic), S2 (non-commercial synbiotic), treatment S3 (combination of commercial and non-commercial synbiotic) and control (C) (witout synbiotic). For commercial synbiotic, a mixture of a commercial Lactobacillus spp. bacteria (at a concentration of 1.5× 106 per g) and mannan oligosaccharide (at a concentration of 1%), and for non-commercial synbiotic, a mixture of a non-commercial Lactobacillus spp. (Lactobacillus plantarum) and mannan oligosaccharide was used. After 2 months of feeding, some of hemolymph indexes such as the number of total haemocytes, and biochemical and immunological parameters such as glucose, total protein, phagocytosis, phenoloxidase and total antioxidant were measured. The results showed that application of the synbiotics (both commercial and non-commercial) could increase the total number of haemocyte significantly (P<0.05). Immunological indicators and biochemical factors in the shrimp fed with different synbiotics, were beter than the control group (P<0.05). According to the results can mention that application of the synbiotics including mananoligosaccharide and Lactobacillus spp. bacteria, specialy if Lactobacillus plantarum was used, has beneficial effects on Immunological indicators of white shrimp.

The Shahid Rajaei Reservoir constructed for various purposes such as drinking water supply. In this context, and also because of the importance of the bloom events and eutrophication process in dams, this paper is to survey the relations between some of physicochemical parameters and phytoplankton composition and density, chlorophyll-a and some water quality indices (Trophic, Saproby, Shannon) using mono and multivariate statistical analysis. Water samples collected from 4 stations during May, June, July, August, September, November and February in 2012-2013. According to the results, the maximum concentration of dissolved inorganic nitrogen, chlorophyll-a, phytoplankton abundance, trophic and saproby indices observed in a month of summer which it was accompanied to the minimum value of species diversity index (Shannon). Pearson analysis revealed direct correlation between abundance of Goniaulax polyedra, Goniaulax digitale and trophic index. In the other words, higher abundance of the two species decreased the water quality. Also based on the PCA analysis, the significant correlation observed between abundance of Cyclotella meneghiniana with Shannon and saproby indices which were negative and positive, respectively. This result indicates to the relation of degradation of water quality with increasing the abundance of Cyclotella meneghiniana. Meanwhile, the presence of the three parameters (abundance of Cyclotella meneghiniana, Shannon and saproby indices) in first component of PCA indicated the important role of Cyclotella meneghiniana and two biological indices in determining of water quality in Shahid Rajaei Reservoir.

Processing technology is important for the export amd import of shrimp and should be selected with regard to the needs of the market and be accepted by GRASS. Therefore, this project was carried out to achievie a proper technology, to maintain chemical, bacterial and sensory qualities and also the safety of shrimp in terms of food hygiene, to increase the shelf life and to detect the proper concentration of 4-hexylresorcinol for processing white leg shrimp. This research evaluated the hypothesis of 4-hexylresorcinol being able to preserve frozen cultured white leg shrimp. The treatments included shrimp immersed in 4-hexylresorcinol (at concentrations of 0.15 % and 0.05 % for 10 minutes) and antioxidant-less shrimp. No Pseudomonas, Vibrio parahaemolyticus, Escherichia coli or Hydrogen disulfide-producing bacteria were observed in either experimental or control samples. Unlike the control samples, Coliform bacteria were not observed in the experimental samples. TVB-N, Trimethylamine, Thiobarbituric acid, Free fatty acids, Peroxide value, moisture, total bacterial counts and Staphylococci counts of experimental and control samples showed significant difference during the storage period (P<0.05). unlike total bacterial counts, Staphylococcus bacterial counts, Coliform bacterial counts, free fatty acids, peroxide value, Thiobarbituric acid, TVB-N and Trimethylamine factors, the factors of pH and moisture of the experimental samples showed no significant difference compared to the control samples (P>0.05). The sensory quality and the shelf life of experimental samples showed significant difference compared to control samples (P<0.05). Chemical, bacterial and sensory factors and the shelf life of 4–hexylresorcinol showed no significant difference among different concentrations (P>0.05). based on the Iranian National Standards, the test samples had a good quality during the period of six months in frozen storage (-18 oC) but the control samples lost their sensory quality in lower than one month.