فصلنامه شیلات
سال هفتاد و سوم شماره 2 (تابستان 1399)

This experiment was carried out to evaluate the effect of adding of Microalgae Chlorella and Germinated Barely Powder in diet on growth performance microbiological counts of common carp. The study was assigned to depend on using of natural products as back to nature in fish feeding. The effect of adding microalgae Chlorella and germinated barely powder in common carp Cyprinus carpio diets with different levels for 84 days and the results revealed a significant role of both additives in each of fish Final wt., Wt. Gain, Specific and relative growth rate. No significant differences observed in FCR, the FER was higher significantly in control, T2 with 5 % Chlorella and T4 with 10 % Germinated barely. The total Bacterial and Enterobacteriaceae count/ CFU was increased in the additives treatments with increasing the levels, the T3 with 10 % Chlorella was higher than control and other treatments were 192.5 and 150 respectively. The control treatment without any addition was higher significantly in Total Bacterial count /CFU in common carp intestine samples, the T4 with 10 % Germinated barely was higher in Total Enterobacteriaceae count/CFU in fish Intestine samples. The highest Coliform bacteria in fish muscles and intestine recorded in T5 and the lowest in T3.

In addition to the development of new technologies to improve the biological conditions of cultured fish, the biochemical nature and physiological functionality of those feed additives strongly affect the stress response. This study explores the effect of dietary arachidonic acid (ARA, 20:4n-6) levels compared with cortisol and glucose levels and whole fatty acid composition in the using Zebrafish as the model organism. Juvenile zebrafish (20-days post-fertilization) fed the five iso-nitrogenous and iso-energetics experimental diets utilizing different ratios of the ARA diet (0, 0.5, 1, 2, and 4% ARA of total fatty acid) for 70 days. Then, Whole-body cortisol and glucose levels were determined, after short-term stress (48 hours’ exposure to starvation). Results showed that the muscle ARA levels were highly correlated to dietary ARA levels. The experiments revealed significant, High ARA levels (2% and 4%) seemed to affect lipid metabolism in complicated ways (p < 0.05). Fish reflected dietary ARA content and post-stress cortisol increased with ARA supply up to 1%, whereas 4% ARA seems to enhance basal cortisol slightly and alter the response to stress. Actually, our results indicate that an ARA-enriched diet induces changes in complex lipids, cortisol and glucose levels, and Overall affect physiological parameters.

Present study was carried out to assess effects of aflatoxin B1 on different rainbow trout tissues. In the present study, 207 rainbow trout fingerlings with an average body weight of 9.67±0.2 g were reared for eight weeks in three distinctive treatments (control group, 25 and 50 ppb aflatoxin B1). At the end of the trial, various tissues of experimental groups were studied regarding probable histological alterations. Histological alterations due to dietary aflatoxin B1 exposure including hyperplasia and lamellar necrosis in the gill, necrotic and vascular changes in the brain along with inflammatory cell infiltration and necrotic changes in the intestinal and pyloric region were evident. The severity of pathologies was more pronounced in those fish received 50 ppb aflatoxin B1 content in comparison to the group fed 25 ppb toxin contaminated diet.

In order to investigate the effect of dietary-vitamin on growth and immunity indices in Nile tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa) in an aquaponics system, 240 tilapia pieces with the average weight of 12 ± 1.25g and 240 seedlings of lettuce were randomly introduced into nine experimental unites. The treatments were different rates of vitamin B3 concentration in the fish feed with the levels of 20, 40 and 60 mg per kg. Growth indices did not show any significant difference among treatments (P≥0.05). Lettuce growth indices such as final leaf length and final leaf width showed a significant difference among treatments (P <0.05). The plant final height, plant fresh weight, plant dry weight, root fresh weight and dry weight were not significantly different (P≥0.05). Biochemical parameters of blood in fish showed the highest mean concentration of total protein, glucose and triglyceride levels in treatment with 60 mg of vitamin per kg compared to other treatments (P <0.05) , however blood indices such as serum cortisol, alkaline phosphatase and aspartate aminotransferase contents were not significantly different (P≥0.05). It was concluded that, with increasing the vitamin B3 at the rates of 40 to 60 mg in feed, can improve tolerance of fish to stress and increase the fish growth and lettuce in the culture system.

Mayflies belonging to the order of Ephemeroptera compose of the most diverse and common inhabitants of aqua systems and are considered as biological and quality index. In this study, biodiversity of Ephemeroptera in Hablehrood River, east of Tehran Province, from 4 sampling points (Simindasht, Mazdaran, Khomedeh and Namrood) was studied. Samples collected weekly through June-September 2016. Samples collected manually by simple forceps from under the bottom rocks and transferred in Ethanol 70% to laboratory for further identification. Total frequencies of the identified genera were compared among different months and sampling points. Five different genera (Acentrella, Baetis, Centroptillum, Cloedes, Rhitrogena) belonging to two families, Baetidae and Heptagenidae, were collected from Hablehrood River, which Acentrella was the most frequent genus (49.7%). Results showed that the most frequency percentage of the collected samples belonged to Khomedeh station through both June and September. Mean number of collected samples of each genus showed no significant difference among different sampling months and sampling points. A part of Hableh Rud river that passes through Tehran province, has a valuable diversity of Ephemeroptera and it is needed to provide optimal habitat for its macrobenthose regarding rural and agricultural pollutions.

The aim of this study was to investigate the effect of absorbent pad containing Carum copticum seed essential oil on chemical and microbial properties of Oncorhynchus mykiss fillet during storage in refrigerator. 10 ml of Carum copticum seed essential oil 1.5 % were added to pad and fish fillets in different treatments, then packed and stored in a refrigerator (4˚C). The chemical (Peroxide value (PV), thiobarbituric acid (TBA) and total volatile base nitrogen (TVB-N)) and microbial parameters (total viable count (TVC) and psychrotrophic count (PTC)) were measured on days 0, 3, 6, 9 and 12. The results showed that fillets treated with absorbent pad and Carum copticum seed essential oil caused slowls the increase process of PV, TBA and TVB-N during storage. The TVC and PTC count of fillets significantly increased during refrigerated storage (P <0.05). But, this increase was less in the treated fillets than the control and increased the shelf life of treated fillets. According to the results of this study, it can be concluded that the absorbent pad containing Carum copticum seed essential oil caused the preservation of fillet quality and it can be used with a natural preservative in fisheries products.

Karaj River, as one of main source of drinking and agriculture water for Tehran and Alborz provinces, has biological potentials, and is one of the protected rivers in Iran. The main purpose of this study was to investigate the concentrations of heavy metals: cadmium, chromium and zinc in the water and sediment samples of Karaj River in order to evaluate the quality of water, using biological value index (Z). Sampling of water, benthos and sediments was carried out from January 2018 to July 2018 from 7 point stations along the river. Preparation of water and sediment samples was performed by evaporation and the studied metals concentrations were measured by ICP device. The obtained results demonstrated that both in water and sediment samples, studied metals showed significant differences from upstream to downstream stations. Also, the concentration of all metals in water and sediment was lower in January than in July. The results of the Z biological value index revealed a significant difference in both seasons between the sampling stations, and the highest value of in both seasons belonged to the downstream stations. Contamination by heavy metals, especially in downstream, is due to human interventions such as agricultural, urban and industrial wastewaters. In the cold season, because of declining population density in the river vicinity area, pollution levels have been decreased. Also, in terms of quality, in general, Karaj River can be classified in saprobe class II and III.

Law of Sturgeon Caviar protection are neither a full-fledged national Law nor a purely legal matter. These Law are tied to Research and Scientific Data proposed by fisheries and environmental scientists, and are built on three pillars, each of which alone is not enough to rely on. International Perspectives on Conventional Law are another factor in expanding the protection of these valuable animals. Thus, with the nationalization of fisheries in our country on the one hand, and the growth of expectations from this sea to alleviate poverty and expanding the trade and oil and gas exploitation industries and in general, increase of the power and ability to capture and have possession on the nature of this sea and borderless pollution on the other hand, national research and international efforts were made to preserve and survive.The result of this research is that although it is now an Economic and Smuggling crime the illegal catch these fish, but the national and international law faces this crime and trade, especially the requirements of international institutions such as International Union for Conservation of Nature (IUCN) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is not efficient and effective, regardless of the data of fisheries scientists and environmentalists in any region. The decision of the Supreme Court as an excellent reaction of local authorities that has been issued regarding about the types of mild and severe violations of the law is important here, given the international requirements. It can be said that the political will of Iranian legislators and decision makers to some extent is consistent to these national, international dimensions, fisheries scientific data from the point of view of species protection and environmental protection of natural habitat and fight against pollution and finally economic attitude to fishing.

In the present study, the effect of pre and post frying treatments on oil absorption and nutritional value of silver carp (Hypophthalmicththys molitrix) fillet were examined. Experimental treatments, including treatment 1 (control): normal frying; treatment 2: drying the fillets at room temperature before frying until reach a constant weight; treatment 3: normal frying, removing the oil from the fried fillet on a strainer in hot air until it reaches a constant weight; treatment 4: was the composition of treatment 2 and 3 (drying the fillets at room temperature before frying, normal frying and removing the oil from the fried fillet on a strainer in hot air until it reaches a constant weight; and the raw fillets were tested without frying. At the end of the experiment, chemical compounds, fatty acid profiles, and AI and TI characteristics of fish fillets were measured in various experimental treatments. The results of the study showed that the frying process caused significant changes in the chemical composition and the fatty acid profile of the fried fillets compared to the raw fillets. Examination of the fatty acids profile of fillet, as well as n-3/n-6 ratio and AI showed that these indicators increased due to normal frying compared to other experimental treatments. Also Frying reduces TI in frying experimental treatments. In general, it can be concluded that the total fat content of fish and the profile of its fatty acids can change during the frying process. Therefore, the use of pre-drying pre-treatment before frying and oil extraction in hot air after frying can be a way to reduce the oil adsorption by fried foods.

The Rashkan area located in the central part of Urmia city near the southwest of Urmia Lake (N 36° 56' E 45° 37'), is important for wildlife especially endemic and migratory birds due to its numerous spring pools. Field inventory along with sampling of water and living aquatic (micro)/organisms were carried out during the spring, April and May 2018, from different 14 locations. Water physio-chemical properties and living crustaceans species were studied. Results revealed that distribution pattern of crustaceans were strongly affected by environmental factors. A number of environmental factors including turbidity, total suspended solids and chlorophyll a have most positive effect on biodiversity indices of the studied habitats. The highest biodiversity of crustaceans in the Rashkan region was recorded during the sampling in May and the lowest one was observed in the first sampling in April. Also, the highest richness and species density was obtained in the second sampling. The results were confirmed by the Shannon-Wiener Biodiversity Index (1.632 in the first sampling compared to 0.816 in the second sampling) and Simpson's Diversity Index (0.494 in the first sampling compared to 0.157 in the second sampling).It can be concluded that the region has relatively good environmental condition for distribution of various crustacean species such as cladocerans, copepods and fairy shrimps requiring more attention by Lake Urmia environmental conservation organizations.

This study aims to assay the main protease (pepsin and trypsin) activity and pepsinogen relative gene expression, as well as histological development of digestive tract in Sobaity from hatching up to 40 days post- hatch (DPH). The results showed that exocrine pancreas, including zymogen granules, differentiated during yolk sac absorption and further developed at 14 DPH. The early appearance of trypsin before mouth opening is attributed to a genetically programmed process. The trypsin activity showed fluctuated pattern (with two peaks at 16 and 30 DPH), coincident with food intake, and related to diet shifting during larval feeding. The most obvious differentiation in the digestive tract was the formation of an incipient stomach surrounded by striated muscle fibers and the development of the gastric glands at 12 DPH. The stomach fully developed at 25 DPH with the transition from striated to smooth muscle cells. The pepsinogen relative gene expression was not detectable before 12 DPH and meaningfully detected at 14 DPH. The pepsinogen expression augmented exponentially coinciding with shifting diet from live to microdiet. Pepsin activity trend was considerably parallel to pepsinogen and started two days after pepsinogen, subsequently increased sharply during the weaning period (25-30 DPH) up to the end of the study. The study concluded that the appearance of the incipient stomach at 12 DPH, early pepsinogen expression, and ontogenetic development of pepsin and trypsin, make it possible to feed Sobaity larvae by inert diet before 25 DPH to reduce the live food consumption and improve the weaning efficiency.