Iranian Journal of Fisheries Sciences
Volume:13 Issue: 2, Apr 2014

Osmoregulation capabilities of two size groups (1 and 2g) of zander, Sander lucioperca, fingerlings were investigated survival rate, plasma osmolarity, sodium (Na+), chloride (Cl-) ion concentrations and cortisol level within 0, 6, 24, 72 and 240 h after abrupt transfer from freshwater to 7 and 12‰ salinity. Also, some hematological parameters were measured at 240h. The plasma osmolarity and ion concentrations (Na+, Cl-) increased immediately after the transference to 7 and 12‰ salinity, reaching maximum at 72h in 1g and at 24 h in 2g fingerlings, and significantly decreased at 240 h, while the freshwater control group maintained almost constant during 10 days which showed lower than the salinity groups. The pattern of cortisol level changes was similar in two size groups after exposure to different salinities and it reflected stress of handling. There were no significant differences between hematological values of two salinity treatment groups than the freshwater control at 240h. The result showed, not only 2g zander fingerlings acted better than 1g in faced with salinity but also the fingerlings weighing 1g could survived and tolerate Caspian Sea water salinity up to 12‰. It is suggested that the release of zander weighing from 1g would help to restocking management of this species in the southern Caspian Sea.

The aim of this study was to detect the occurrence of parasites in Prussian carp, Carassius gibelio as the most important alien fish in Anzali international wetland. This undesirable fish was introduced accidentally to Iran with Chinese carp fries which imported to the country during the last decades and then acceded to Anzali wetland. Today this fish has significant stocks in Anzali wetland; but there have been limited studies about the parasites of this fish in Anzali wetland. During this study a total of 90 Prussian carp were collected by electrofishing and gillnets from April through July 2012. After recording biometric characteristics, common necropsy and parasitology methods were used. A total of 2715 individuals out of 11 parasite species were recovered. Parasitofauna consisted of: two protozoans, Ichthyophthirius multifiliis and Trichodina sp.; one nematode, Raphidascaris acus; one trematode, Diplostomum spathaceum; six monogeneans, Dactylogyrus formosus, Dactylogyrus dulkeiti, Dactylogyrus baueri, Dactylogyrus arquatus, Dactylogyrus inexpectatus and Gyrodactylus kobayashii; and one crustacean, copepodid stage of Lernaea cyprinacea. The monogeneans had the highest prevalence values (88.89%). The occurrence of D. inexpectatus in C. gibelio is reported for the first time in Iran.

The harmful effects of ultraviolet radiation on aquatic animals, due to ozone layer reduction, have been long studied in recent years. Exposure of Rainbow Trout larvae (Oncorhynchus mykiss) to Ultraviolet-B radiation (UV-B) at different doses (68.75 µw/cm2 and 94.83 µw/cm2 as the minimum and maximum dose of UV-B in natural environment respectively) for 15 minutes once a day in dark condition in comparison to control group (without any solar or UV) showed a wide variety of body abnormalities and eye damages. Body curvature, yolk sac edema, fin blistering, dwarfism, eye and head abnormalities as morphological malformations were revealed during the experiment, none of the malformations were observed in control group. Histopathological changes in retina such as irregular and discontinues pigmented epithelium, necrosis of photoreceptors and degeneration of nucleus layers confirmed the destructive effects of UV-B radiation in the eyes of Rainbow Trout. Such changes in larvae can be valid as bio-indicator for pollution and UV radiation and also introduce fishes as model for toxicological studies.

Current microbial methodologies to determine fish quality are laborious and have long time required to obtain results. The impediometric technique as a rapid sensitive method was used to determine the correlation between impedance detection times (IDTs) and conventional reference psychrophilic and mesophilic plate counts of fish in order to develop models for predicting the microbial quality and determining fish shelf-life. The changes in sensorial factores, psychrophilic and mesophilic bacterial loads of ice stored fresh silver pomfret (Pampus argenteus) were measured by two different methods including conventional reference plating techniques and also impediometric monitoring method at 0, 3, 6, 9, 12, 15, 18, 21, 24 and 27 days of storage. The primary psychrophilic (3.44 ± 0.69 logCFU/g) and mesophilic (3.64 ± 1.08 logCFU/g) bacterial loads increased to more than acceptable limit (6 logCFU/g) on days 12 and 21, respectively. The calibration curves for the two methods and their equations were designed with linear regression models. IDTs were highly correlated with psychrophilic (r=-0.9614) and mesophilic (r=-0.9547) bacterial loads. This study suggests that impediometric technique can be used as a rapid and reliable method to accurate estimation of silver pomfret bacterial loads and determine its shelf-life as seafood. According to results, the sensorial data were correlated with psychrophic bacterial load. The shelf-life of ice stored silver pomfret determined 9-12 days based on sensorial data and psychrophic bacterial load.

Acipenser stellatus is one of the most invaluable species of Sturgeon fishes in the world. The purpose of this study was to identify the resident microbial community from the gastrointestinal tract (GIT) of Acipenser stellatus. One hundred and twenty three fungi were isolated from the GIT of 7 Acipenser stellatus samples including Aspergillus spp (45.5%), Trichoderma spp (8.9%) and Cladophialophora spp (8.1%). Among different Aspergillus isolates, A.niger was the predominant species. Although, fungi were predominantly isolated from stomach (36.6%), but with respect to frequency of fungal isolates there were no significant differences between stomach and other parts of GI. In general, the bacterial isolates recovered were mostly gram negative and related to Enterobacteriaceae family such as Aeromonas, Pseudomonas and Salmonella species. The most bacterial species were isolated from intestine and pre stomach region (88.2%). It is concluded that A. niger and Aeromonas species were predominant fugal and bacterial microbes isolated from understudy fish GIT, respectively.

The movement parameters of yellow fin tuna schools were analyzed by means of scanning sonar in tuna purse seine capture situations in the Oman Sea in June 2010. There was significant difference in swimming speed and radial swimming direction between the escaped and captured schools. In escaped cases, the fish schools swam faster with mostly horizontal avoidance behavior to the sound stimuli from the surrounding vessel and escaped capture under the sinking net at last. The swimming speed of the schools in two occasions was correlated to the vessel’s speed. Some alternatives of new constructions of the nets with regard to the sinking speed are discussed that may reduce the potential problem of escape capture during purse seining process

The effects of Mentha pulegium water extract dipping on quality and shelf life of silver carp during superchilled storage were investigated. Fish samples were treated with water extract of 1 and 3%M.pulegium, and then stored at -3 οC for 30 days. The control and the treatedfish samples were analyzed periodically for chemical (pH, PV, TBA, TVB-N), and sensory characteristics. The results indicated that the effect of M.pulegium extract dipping on fish samples was to retain their good quality characteristics and extend the shelf life during superchilled storage, which was supported by the results of chemical and sensory evaluation analyses. Inthis respect, the sample supplemented with 3% water extract was more potent compared with the 1% one in extending the shelf life of fish fillets.

In this study, sperm characteristics (motility parameters and ionic composition of seminal plasma) and effect of ions on motility (duration of motility of sperm and percentage of motile spermatozoa) and fertilization capacity (fertilization rate, hatching rate, survival rate and larvae length) were investigated in Ctenopharyngdon idella. The longest duration of motility obtained in solution containing 104 mM NaCl. The highest fertilization capacity was observed in solution containing 112 mML NaCl. Solutions containing different concentrations of KCl caused a decrease on the percentage of motile spermatozoa; fertilization rate and hatching rate, but duration of sperm motility and survival rate were significantly higher in solution containing 440 and 320 mM KCl, respectively. There was a decreasing trend on motility when spermatozoa incubated in solutions containing MgCl2 compared to the control. Similarly, higher motility parameters in terms of percentage of motile spermatozoa and duration of sperm motility were observed in distilled water. The sperm motility just after activation was suppressed by concentrations of CaCl2 of 32 mg/dL or more. The maximum hatching rate, survival rate and larvae length were observed in 32 mg/dL CaCl2. Understanding the effects of these ions is helpful to the aquaculture industry as it allows for the development of optimal artificial reproduction methods and contributes towards the knowledge base of better short-term fish semen preservation conditions.

Body composition and fatty acid profile of the body tissue of Caspian kutum (Rutilus frisii kutum) fish larvae were determined from fertilized egg to 50 days post hatching (dph). Feeding with rotifer started from day 3 to day 7; thereafter they were fed with dry food until the end of the experiment. The changes observed in lipid content and the decrease in lipid levels during larval ontogeny reflect the utilization and mobilization of lipids during both embryogenesis and larvae development. During this study, palmitic and stearic acids were the most abundant saturated fatty acid (SAFA).In kutum larvae, no utilization of palmitic and stearic acids was observed until 20 dph. It thereafter was utilized as an energy source. Oleic and palmitoleic cacids were the predominant monounsaturated fatty acid (MUFA). Oleic and palmitoleic acids utilized until 10 and 25 dph, respectively; thereafter they increased. DHA, EPA and ARA were the major polyunsaturated fatty acids (PUFA). The decrease in levels of DHA and EPA denotes their utilization as an energy substrate by kutum larvae. ARA decreased during larval ontogeny, reflecting dietary values. With regard to reared kutum larvae in fresh water and the low levels of HUFA in larval diet, it can be said that kutum larvae possibly are quite capable of elongating and desaturating C18 to C20 PUFA. In case of proximate analysis, the percentage of body protein and ash increased trend during ontogeny while the percentage of body lipid and moisture decreased trend during larval growth.

A Gram-negative, rod-shaped, motile and halophilic bacterium identified as Vibrio harveyi was isolated from hatchery-reared larval of Iran Shrimp Research Centerfollowing mass mortality. Seven isolates of Vibrio spp.were collected from nauplii of Litopenaeus vannamei and then were evaluated for characteristics including morphology, physiology and biochemistry. The results indicated that the isolates belonged to a single species that grew on Thiosulfate citrate- Bile Sucrose agar and in 1.5 to 6% NaCl, positive lysine and ornithine decarboxylation and susceptible to O/129 disk. Identification of Vibrio harveyi strainIS01 (1 of 7 isolates) was confirmed by Polymerase Chain Reaction assay for Vibrio harveyi (expected amplicon 1493 bp). The 16S ribosomal DNA sequence (National Center for Biotechnology Information, GenBank accession number GU974342.1) gave 99% sequence identity to V. harveyi ATCC: 35084 (GenBank accession number EU130475.1).

Sushi, a very popular food worldwide became a popular ready-to-eat food selling in supermarkets, but it exhibit distinct features, which are associated with microbiological hazards. Therefore, MAP technology, known to reduce aerobic bacteria in fishery products, was used to improve quality of ready-to-eat salmon sushi in this study. Salmon sushi were packaged with air (control), 50%N2 /50%CO2 (MAP-a), and 100% CO2 (MAP-b), stored at 4 ±1°C for 6 days and analyzed every day. During the study, control samples taken the lowest sensory scores. The total color change (ΔE) was lower in MAP samples comparing to controls. Likewise, mesophilic and psychrophilic aerobic bacteria counts of gas-treated samples were significantly lower. These results show the positive effect of MAP technology on the quality of salmon sushi. Regarding the improving demand to ready-to-eat sushi selling in supermarkets, this result will be useful in further studies and commercial applications.

This study focuses on Anguilliformes specimens revising which collected during 2006-08 in some Iranian museums. For this study, all museum samples from Iranian coastal waters of the Persian Gulf and Oman Sea were investigated. The results indicated that species diversity in the Iranian waters can be classified into six families of Anguiliformes (Eels and Morays fishes). A total of 11 species - consisting of six families have been identified, of these the highest species diversity belongs to the Muraenidae with five genus and eight species. Also, there were two endemic species Muraenesox cienerus (Muraenesocidae) and Gymnothorax undulates (Muraenidae). More than ten rare species were the first report and record from Iranian territorial waters. There are Ichthyapus acuticeps, Synaphobranchus affinis, Strophidon sathete, Rhynomuraena quaestia, Gymnothorax johnsoni, G.kidako, Muraenesox bagio, Pseudoxenomystax albescens, Muraenesox talabonoides, and Conger cinereus cinereus.

The study and research of abundance and diversity variation of fish larva (Ichthyoplankton stages) was done in Gowatr Bay during autumn 2006 - summer 2007. Five stations were selected for sampling, and Bongo-Net with 300µ mesh size was towing from bottom to surface. During of survey, totally 531 larvae belong to 11 families were collected and identified. The mean abundance estimated 12.17 larvae per 10 m2, which three fish larva family including: Gobiidae, Clupeidae and Engraulidae were dominant (86% of relative abundance). The result showed that there was significant differences between pre and post-monsoon fish larvae abundances (p<.05), and there were not significant differences between stations (p>.05). In pre-monsoon 4 families were identified of which Clupeidae introduced as indicator group, whereas in post-monsoon 10 families were identified and Gobiidae was indicator family, accompany with increase of diversity. PCA result was shown, temperature as the main factor affected on fish larvae assemblage was found with a significant decrease of 11.9 °C after monsoon phenomenon.

Seasonal variations of zooplankton communities were studied in the southern Caspian Sea for 4 successive seasons and 8 transects with 5 stations from 5 to 100 m depths which sampled during 2009. The zooplankton population constituted of 73.33% copepods, 24.21% rotifers, 2.23% cladocerans and 0.23% protozoans. Copepods were dominant at all stations with a density between 1456±531 ind. m-3 (Transect 8) to 4524±1215 ind. m-3 (transect 2). The predominant species of copepods was Acartia tonsa constituting 99.50% of all copepod populations. They were most abundant during warm months of summer in the upper layers (surface to 20 m depth) while rotifers replaced them during cold season. The maximum density of zooplankton was observed in the west decreasing towards the eastern parts of the sea.

The coastal area of the Caspian Sea and Gorgan Bay are important ecosystems receiving discharge from their tributaries. In this study, concentration of lead (Pb), cadmium (Cd), zinc (Zn) and chromium (Cr) was seasonally determined at 8 sampling points during 2009-2010. Water samples were collected from the sampling stations and transferred to laboratory in polyethylene containers, whereas, sediment and benthic fauna samples were collected using a Van Veen grab. The levels of heavy metals were determined by atomic absorption spectroscopy method. Results showed that range of Pb, Cd, Cr and Zn in the water samples were 80-123, 61-97, 63-87 and 82-120 ppb, respectively; and their ranges in the sediment samples were 479-1072, 98-293, 102-622 and 937-1577 ppb, respectively. The range of Pb, Cd, Cr and Zn in the benthos samples were 95-132, 59-110, 26-58 and 103-155 ppb, respectively. Zn and Pb were the most concentrate metals in all samples. Likewise, sediment had the highest heavy metal content amongst the samples. This study demonstrated that the level of metals in the environment is increasing, bringing a serious warning to industries and threat of man-made contamination, which can be restricted and a necessity to control ecosystem and food-chain pollution

Numerous reports on existence of white cysts in musculature of skipjack tuna Katsuwonus pelamis and lack of information about the quality of cysts and individual responses of fish to them led the authors to focus on this fish as a commercially valuable species. This study investigated the histopathologic responses of skipjack tuna to highly prevalent cystic larval stages of Trypanorhyncha. Some 92.25% of 400 examined skipjack tuna of Oman Sea (Iran) captured from processing center in Chabahar have been diagnosed infected by Trypanorhyncha Larvae through gross muscle examination. Minimum of 5 to maximum of 19 cysts were observed per each flank flesh with no significant difference between number of cysts from right (9 ± 4) and left flanks (10 ± 4) and also males and females (p>.05, t- student test (spss version 16)). Using hematoxylin and eosin (H&E) staining of 4µm sections of surrounded cysts with muscle and light microscopy observations each metacestode was distinguished encapsulated by surrounding fibrous cyst wall consists of thin inner layer and a thick outer layer with the minimal histopathologic changes around it. The highly prevalent Trypanorhyncha infection in Oman Sea represents the high rate of infection among elasmobranches. The ability of encapsulated parasite to escape from the immune system of the host is assumed as one reason for the observed minimal tissue response in infected fish and the continuation of infection among elasmobranches and teleosts of Omen Sea.

The objective of current study was to investigate the effects of whey protein coating on the quality of common kilka during frozen storage period. For this study, common kilka was coated with 12% whey protein concentration. Also, non- coated kilka was used as a control sample. Coated and non-coated samples were then stored at -18 oC for six months. Bacterial, chemical and sensory properties of the samples were determined in each month. Results showed that total bacterial counts and Staphylococcus bacteria count were lower in the test samples compared to the control samples. Coliform, Escherichia coli and Pseudomonas bacterial contamination were negative till the end of the storage period in the covered samples. Chemical factors consisting of humidity, protein, lipid, ash and calorie were higher in the test samples compared to the control samples. Peroxide value, free fatty acids, thiobarbitoric acid, TVB-N and pH were lower in the test samples. Sensory tests had a better quality in the test samples compared to the control samples. No statistically significant decreases were observed in chemical factors in the covered samples compared to the control samples (p<.05). In sensory specifications, there was a significant difference between the covered samples and the control samples (p<.05). According to the results of experiments and statistical analysis, the covered samples had a favorable quality till the end of the storage period but the control samples had lost their quality.

White spot syndrome virus (WSSV) is a pathogen that causes high mortality in shrimp culture in the whole world. Sequence analysis of WSSV has shown similarity of WSSV isolates in different countries with exception of a few variable genomic loci. This study investigated the sequence variation of some Iranian WSSV isolates and previously identified isolates. Samples were collected during target surveillance and were feed, broodstock, post-larvae, artemia, crabs, and wild and cultured shrimp of northern Persian Gulf (Boushehr and Khuzestan provinces). The open reading frame (ORF) 94 sequence of different Iranian WSSV isolates were amplified using specific primers from positive samples. The ORFs 94 sequence of positive samples were sequenced and registered in the Gene Bank and then compared to other WSSV isolates. The number of repeat units in ORF94 showed that WSSV isolates were varied in number. There are SNPs (G and T) in position 48 of RUs that varies in different Boushehr and Khuzestan isolates. Also these sequences were compared to Gene Bank WSSV isolates and showed a high similarity (>90%) to Southeast Asian countries. To our knowledge this is the first report of sequence analysis in Iranian WSSV isolatesapplications