فصلنامه شیلات
سال هفتاد و دوم شماره 3 (پاییز 1398)

In this study, the effects of different dietary protein and lipid levels including three dietary protein levels (35, 40 and 45%) and two dietary lipid levels (7 and 14%) were investigated on growth indices and hepatosomatic and viscera somatic index of Sobaity seabream juvenile (Sparidentex hasta) in triplicates. Fish with the mean initial weight 36.55±0.28 g were randomly introduced in eighteen 300 l polyethylene tanks and fed dietary treatments three times daily to satiation for a 56- day period. According to the results, weight gain and specific growth rate were significantly affected by different levelsof dietary protein (P<0.05). But varying levels of dietary protein and lipid had not any significant effects on condition factor, intraperitoneal fat percentage and feed intake (P>0.05). At the 14% dietary lipid level, hepatosomatic and viscera somatic index, protein efficiency ratio and carcass lipid content increased significantly(P<0.05). However, the food conversion ratio significantly decreased. With increasing the dietary lipid level, protein retention decreased and energy retention increased significantly. The highest nitrogen retention efficiency was observed at 40% protein level. Dietary protein and lipid levels significantly affected carcass protein and lipid contents (P<0.05), but had not any significant effect on moisture and ash contents (P>0.05). It was concluded that Sobaity seabream juveniles are able to utilize protein in 14% dietary lipid. Therefore, with increasing dietary lipid level to 14%, dietary protein level can be reduced to 40% in Sobaity seabream juveniles (S. hasta).

Synthetic preservatives have been used in the food industry for many years. However, studies have shown that some of the synthetic preservatives can be dangerous for human health. Therefore, research on natural alternatives attracted more attention, recently.The purpose of this study was to evaluate the preservative effect of Marjoram extract at different concentrations (0 (control), 3, 6 and 9%) for injection before slaughtering the rainbow trout fillet during the refrigerated storage. Thus, 2 ml of blood was drawn from live fish and immediately 2 ml of each concentration of Marjoram extract injected to the live fish. Approximately, 30 minutes after injection, the fish were slaughtered (out of water), and then the fillets were refrigerated for 16 days. The quality of samples was determined by testing the pH, spoilage microorganisms and secondary lipid oxidation, Hem iron and total volatile nitrogen compounds on days 1, 4, 7, 10, 13 and 16 of storage. The results showed that pre-slaughter injection of Marjoram extract significantly effects on the survival of treated fish. Also, severity of spoilage of the treated fish was reduced (p<0.05). The results of thiobarbituric acid index and the index of nitrogen compounds, indicated that the Marjoram extract was able to delay the lipid oxidation and decomposition of protein synthesis in rainbow trout fillets. Therefore, application of marjoram extract at 9% for survival of rainbow trout fillets is recommended.

This study was conducted to identify different stocks of big marine catfish (Netuma thalassina) as the most dominant marine catfish species in Hormozgan waters using morphological features. 209 big catfish were caught in three different habitats of marine Catfish in Persian Gulf and Oman Sea including Bandar Abbas, Bandar Lengeh and Jask, and the left side and ventral profiler of all samples were photographed. A total of 12 landmarks on the lateral side and 11 landmarks on the ventral homolog were defined on pictures, and digitized by using software tpsDig. Body. Moreover 20 geometric distances between ten landmarks, 9 traditional morphometric features were analyzed using discriminant function analysis (DFA) in different areas. The results of CVA analysis in ventral view of head shape and lateral view according to Mhala Anubis intervals showed that Jask catfish population separated from other groups. Based on ventral view of head shape, the most displacement of landmark parts were related to the tip of the snout, length and width of the head in the Lengeh population which had a shorter head length, wider head and mouth rather than Bandar Abbas and Jask catfish population. The total mean of lateral view showed that the most displacement between landmark points were related to the tip of the operculum, the height of the body and caudal peduncle area. On the other words, Jask catfish population had a thinner body height and longer body length compared to other groups. The results of discriminant function analysis (DFA) classified in an average of 94.7% individuals in their original population. In conclusion, our results showed a high phenotypic variation in big catfish stocks in Iranian coasts of the Persian Gulf and Oman Sea.

The present study was performed to evaluate the effects of diets supplemented with green tea catechin on growth performance, metabolism, and some mucosal immune parameters in crucian carp (Carassius carassius). Seventy-two healthy fish with mean weight 8.03 ± 0.36 g were randomly distributed into three treatment groups with three replicates in each group and 12 fish in each aquarium. Fish in treatment groups were administrated with 100 and 500 mgkg-1 catechin for 45 days. Results showed that growth performance did not change in treatment groups compared to the control group (P>0.05). Serum biochemical parameters including glucose, triglyceride, and total cholesterol levels in both treatment groups decreased with respect to the control group (P<0.05). Mucosal immune parameters, namely lysozyme and alkaline phosphatase showed higher activity in both treatment groups compared to the control group (P<0.05). In contrast, protease activity increased in higher dose group in comparison with the control group (P<0.05). The results indicated that green tea catechin, especially at 500 mg kg-1, could exert beneficial effects on some biochemical parameters and skin mucosal immunity in crucian carp.

In this study, membrane process was used to remove omega-3 from the black sea spratClupeonella cultiventrisfish oil. For this purpose, neat polymeric membranes containing 14-17wt.% polyethersulfone (PES) were fabricated by wet phase inversion technique and used for omega-3 removal. Gas chromatography (GC) analysis of permeate showed that the neat membrane containing 17wt.% PES has the best maximum performance for omega-3 removal (nearly 60%). To increase the oil permeation, stearic acid, paraffin and glycerol monostearate additives were added to the polymeric solution as lipophilic compounds and then the properties of the synthesized membranes were investigated using the Scanning electron microscope (SEM) and contact angle (CA) analysis. The SEM results showed that the addition of these materials did not change the synthesized membranes’ morphology significantly compared to neat membrane. Contact angle analysis results also indicated that the lipophilicity of the membranes increased by addition of the lipophilic compounds. Liquid-liquid displacement test showed that the pore size of the neat membrane is in the ultrafiltration range, which is suitable for the removal of omega-3 molecules with a molecular weight of nearly 1000 Dalton as well. Addition of the lipophilic compounds increased thepermeation flux and reduced the percentage of omega-3 removal compared to neat polyethersulfone membranes.

This study was conducted to investigating the effect of dietary supplemented by butylated hydroxytoluen (BHT), a synthetic antioxidant, and oxytetracycline (OTC) on superoxide dismutase (SOD) on content of the liver in rainbow trout(Onchorhyncus mykiss) experimentally exposed Aed against Aeromonas hydrophila. Fish were divided into experimental treatments in triplicates and received the following experimental diets, after bacterial exposure ( CFU/ml through peritonile injection), for 2 days:(E)-control; (B)- OTC,; (C)- OTC plus dietary 0/5 % BHT; (D)- OTC plus dietary 0/8 % BHT(9 g OTC, effective dosage 20%, was administrated in diets for three treatments as mentioned above, B, C and D). After fish liver sampling, OTC was omitted from(C) and (D) treatments and experiment was continued by: (C1)- dietary 0/5 % BHT (D1)- dietary 0/8 percent BHT, for 7 days and final sampling was applied. Statistical analysis in SAS 9.2 software showed that using the dietary supplemented by OTC and 0/5 % BHT during antibiotic treatment as well as using dietary supplemented by 0/8 % BHT in following antibiotic treatment can induce of SOD increase in the liver of fish.

This study was designed to determine the sediment structure, Total Organic Matter (TOM) and facultative anaerobic bacteria communities of sediment affected by cage culture of rainbow trout in the coastal waters of Abbas Abad area (southern basin of the Caspian Sea). For this purpose, sediment samples were collected at distance of 5, 50, 100 and 1000 m from the cages in December 2014 (before the culture period), March and April (production period) and August 2015 (after the culture period). Determination of sediment grading showed that its structure was composed of silt-clay (91.7%) and very fine sand (6.44%) and the sediment structure was not affected by the cage culture. The Total Organic Matter was significantly different only between the sampling periods (P<0.05) so that the highest amount of Total Organic Matter (TOM) was observed during the production period whereas, it was not affected by the distance from the cages (P<0.05). It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on the factors studied in the vicinity of small scale fish cages due to the short duration of cage culture and strong water currents, so that observed changes were more associated with seasonal fluctuant.

Pacific white shrimp (Litopenaeus vannamei) is an important economic species in aquaculture industry. Effect of cinnamon, star anise, ginger, fennel, nutmeg, licorice, dried apple peel and spice mix on lipid and protein oxidation of shrimp mince during refrigerated storage at 4 ºC for 8 days was evaluated. Total phenolic contents in all spices were between 669.7 and 1538.4 mg gallic acid equivalents /g dry matter. Licorice, cinnamon and spice mix at 100 µg gallic acid equivalent/ g mince led to the best odor and color in samples after 8 days of storage (P < 0.05). These minces showed lower protein carbonyls and higher total sulfhydryl groups with the coincidental lower lipid oxidation (P < 0.05). In minces incorporated with nutmeg or fennel extracts, rancid odor was noticeable with higher formation of protein carbonyls and TBARS. Ginger-treated mince showed the lowest bacterial count (4.16 log CFU/g) at day 8. Spice mix extract showed antioxidant activity in scavenging free radicals (DPPH, ABTS, and hydroxyl) with IC50 of 15.1, 92.1 and 72.4 ppm, respectively. Results indicated the effect of spice mix in oxidative stability of vannamei shrimp mince during 8 days of refrigerated storage.