Iranian Journal of Fisheries Sciences
Volume:20 Issue: 2, Mar 2021

Ribbonfish, Trichiurus lepturus (Linnaeus, 1758), is an important component of subsistence fisheries throughout its tropical and subtropical distribution. The catch rate of ribbonfish has increased seven-fold in a decade in the Persian Gulf and Oman Sea. We collected monthly biological samples from T. lepturus, to estimate growth and mortality parameters, and identify species reproductive patterns. The annual instantaneous rate of fishing mortality (0.63 year-1) was higher than the target (Fopt= 0.26 year−1) and limit (Flim= 0.35 year−1) reference points, indicating that the ribbonfish stock is overexploited. The gonado-somatic index and monthly gonadal maturity stages of harvested fishes indicated that T. lepturus presents continuous reproductive activity throughout the year, peaking in the four months from March to June. The size at first maturity was estimated at 66.9 cm total length for females. The overall sex ratio differed significantly from the expected 0.5 with a larger proportion of females (χ2 = 203.10; p < 0.001).  The current study provide important information that can facilitate management, conservation, and sustainable fishing of T. lepturus in the Persain Gulf.

Most hatcheries in China rely on live prey for successful rearing of fish and shrimp larvae. Besides the high costs, live prey with pathogenic bacteria also increases the risk of contracting foodborne diseases. More than 3.5 billion large yellow croaker (Larimichthys crocea) larvae (total length over 4-centimeters) were raised in 2016. However, no formulated diet is available for replacing live feed in early stages of this croaker so far. In the present study, a new microdiet (Yq) is investigated for rearing croaker larvae at early stages (15 days after hatching). A commercial import diet (Cd) and live prey (Lp) were fed as controls. About 20,000 larvae per tank were hatched from Ningde Fufa Fishery Company in May 4th, 2017. Quality parameters, such as growth performance, survival and three digestive enzyme activities were measured. The survival rate of Yq (58.5%), Cd (51.5%) and Lp (69.6%) exhibited no significant difference (p>0.05). Furthermore, the cost of Yq was only about 23.3% of the cost of Lp. Specific growth rate in Lp was about 8 times higher (p<0.05) than that in two other microdiet treatments. Tryptic activity was slightly higher than other enzymes’ activities, revealing that trypsin plays an important role in the degradation process of large yellow croaker larvae. In the Lp group, tryptic activity was 4 times higher than that of the other two groups. In addition, the activity of three diets on α-amylase and lipase activities were not significantly different (p>0.05). The high survival rate and low cost of Yq showed that it is suitable in rearing Larimichthys crocea larvae at the early stages.

The production of single cell protein (SCP) is one of the cheap protein sources for use in aquaculture. In this study, Claveromycice frajilice and  Fusarium oxysporum were used to produce SCP using Kilka stick water as the source of medium. Adaptation of C. frajilice and F. oxysporum to pure stick water was performed by increasing the concentration of stick water in distilled water. Treatments included 50% and 100% stick water, and a group without stick water as control. The pattern of the yeast and fungus growth was studied by spectrophotometry at 600 nm. The final product was analyzed for values of dry materials, amino acids profiles, total protein, moisture and ash. The results showed protein production by C. frajilice in 50% and 100% stick water was 55.35% and 57.47%, respectively, compared to 54.65% in control group (P>0.05). Protein production using F. oxysporum was 53.17% and 54.39±0.45% in 50% and 100% stick water, respectively compared to 49.71% in control group (P>0.05).  The results showed that amino acids composition in produced SCP was comparable with the suggested profiles of requirement by FAO/WHO and NRC. Based on to the obtained results, application of pure Kilka stick water is suitable for production of C. frajilice as the source of SCP.

The variation in otolith shape of three syntopic species of mudskippers Boleophthalmus dussumieri, Periophthalmus waltoni, and Scartelaos tenuis from the tidal flats of Qeshm Island in Persian Gulf was studied based on Elliptic Fourier Analysis. Principal component analysis and Discriminant analysis could separate the specimens of every species with 100% classification success, which proves the variability of otolith among the three fish species. Cluster analysis produced two main clusters, one cluster encompasses only specimens from P. waltoni and the other contains S. tenuis and B. dussumieri. The result of the present study revealed the power of geometric morphometrics in discriminating the three mudskippers. It is also concluded that otolith traits especially its geometric morphometric could be regarded as an invaluable source of information for paleontology, phylogeny, taxonomy and ecology of fishes.

Tight junction protein, occludin, plays an important role in intestinal health of fish. To study the function of occludin in the intestinal barrier at the protein level, a rabbit occludin polyclonal antibody was prepared against heterologously expressed Cyprinus carpio A fragment of the occludin gene containing antigenic determinants was first ligated into the pET-21a, which is an expression vector and transformed into E. coli BL21 (DE3) strain. Expression of the target fusion protein was induced by isopropyl-beta-D-thiogalactopyranoside (IPTG). The purified fusion protein was used as an antigen to immunize New Zealand long-eared rabbits (Oryctolagus cuniculus) through ear margin vein and subcutaneous injection to obtain rabbit anti-carp polyclonal antibodies against occludin. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the antibody titre, and the antibody was used to determine the distribution and expression of occludin in the intestine of carp after infection with Aeromonas hydrophila. The target fusion protein had a molecular weight of approximately 31.7 ku, the antibody titre was 2.4 × 106, and the integrity of occludin protein was lower in various intestinal segments after A. hydrophila infection. The results indicated that the prepared antibody had a high titre, affinity, and specificity and can be applied to study the expression and distribution of occludin in C. carpio. The availability of this polyclonal antibody laid the foundation for the systematic study of the intestinal barrier of Cyprinus carpio . Additionally, this polyclonal antibody could also be used for explorative studies of the biological function of occludin in other fishes.

The blue-green algae Spirulina platensis was cultured with different nitrogen regimes (NH4Cl, NH4NO3 and KNO3) with concentrations of 0.010, 0.025 and 0.050 M and then fed to Litopenaeus vannamei at 19 days post hatch (PLI) to evaluate the nutritional quality. At the end of the experiment, growth and survival rate were determined, and the larval development was calculated. The maximum protein content was obtained in culture media containing NH4NO3 followed by NH4Cl and KNO3 (p>0.05). Moreover, in all S. platensis cultures, increases in nitrogen concentrations led to increases in protein content. The present study showed that, with the exception of shrimp larvae at 5 days post hatch, L. vannamei shrimp larvae fed on S. platensis cultured in NH4NO3, as a nitrogen regime, generally developed significantly (p<0.05) faster to next stages compared with the other treatments. However, the survival rate (%) and total length (mm) of shrimp larvae fed on S. platensis did not show any significant difference (p>0.05) when the nitrogen was varied in terms of regimes. Overall, the study points to the potential effectiveness of using NH4NO3 as a nitrogen regime in S. platensis culture media in producing live food for the hatchery production of L. vannamei shrimp larvae.

Determining trophic condition of a wetland is an important step in scientific assessment of the aquatic ecosystem. High levels of nitrogen and phosphorus, is mainly the result of human activities in agriculture, industry, etc. Increasing levels of nutrients result in eutrophication of water ecosystems. Regarding the importance of Anzali international wetland, the present study conducted several models of Carlsons on trophic status of the wetland through 1985, 2007, 2014 and 2017. The evaluated stations include, Bandar Anzali under bridge, Sorkhankal, PirBazar, Siadarvishan, Nokhaleh, east of wetlands, Hendkhaleh, and west of wetland. The results of Analysis of Variance indicated significant difference (p<0.05) among values of the indicators listed in stations and different seasons. Assessment of trophy index (TSI) on total phosphorus (TP) and total nitrogen (TN) in order to reveal wetland condition determined oligotrophic and mesotrophic conditions in 1985 to acute hypertrophy in recent years. The results showed increase in the amounts of phosphorus and nitrogen during 1985 to 2017.

Kakuti, Ziziphora clinopodioides, is a medicinal herb found in Iran, but its potential benefits have not been studied on fish. Thus, the aim of the present study was to investigate the effects of Kakuti aqueous extract on the plasma antioxidant and enzymatic parameters in common carp, Cyprinus carpio. The aqueous extract was prepared by boiling Kakuti leaves for 2h. Four diets containing %0 (Ctrl), %0.5 (0.5E), %1 (1E), and %2 (2E) of Kakuti extract were fed to fish within a 60-day period. For each diet, three tanks, each with 15 fish with initial weight of 46.2±0.16g, were assigned. Then, blood samples were taken from all treatments to assess plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), glucose, superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). The results showed that %1 Kakuti extract significantly decreased plasma AST and ALP, but increased CAT activities. There was no significant effect of dietary treatments on plasma ALT activity. 0.5 and %1 Kakuti extract decreased plasma glucose levels significantly, but increased plasma SOD activity. 1 and %2 Kakuti extract decreased plasma MDA levels significantly. According to the results, Kakuti extract is capable of augmenting antioxidant strength, that in turn, may be the reason for boosted tissue health in common carp. Dietary %1 Kakuti extract is recommended for inclusion in common carp diet.

The effects of Yarrowia lipolytica lipase 2 (YLL2) on growth performance, digestive enzyme activity and muscle nutritional components of Russian sturgeon (Acipenser gueldenstaedtii) were evaluated in a 56-day feeding experiment. Four experimental groups of fish with mean weight of 4.465 g were used in the study: Control group (0-control), Group 1 (1.0 g/kg YLL2), Group 2 (1.5 g/kg YLL2) and Group 3 (2.0 g/kg YLL2), respectively, with three repetitions. Fish fed diets with YLL2 at 1.0 g/kg showed the highest growth compared with that of the other groups (p<0.05). For nutrient apparent, docosahexenoic acid (DHA) and eicosapentenoic acid (EPA) concentrations in fish muscle of group which fed with 1.0 g/kg YLL2 increased 5.05% and 7.45% respectively, compared with that of control group (p<0.05). Considering the digestive enzyme activity, lipase and protease activity in liver, spleen and intestine of G1 fish was also significantly enhanced compared with that of control group (p<0.05). While, significant increase of amylase activity in intestine was only observed in fish treated with 2.0 g/kg YLL2. The present results suggested that YLL2 (1.0 g/kg) could be used as potential diet additives for aquaculture Russian sturgeon.

Lack of information about ichthyofauna makes it difficult to predict human effects on the communities. In this study, the effects of the environmental and human factors were examined on altitudinal patterns of fish habitat selection, faunal changes, species richness and fish abundance from upstream to downstream in the southern part of the central Alborz Protected Area during 2016 and 2017. 366 fish individuals of five species in three families were identified and brown trout was the dominant species. The river was divided into three zones based on habitat structure, species composition and influence of physical and chemical variables. The results indicate that, in some situations, including small changes in habitat structure indices, physical and chemical variables along the altitudinal gradient are more effective in habitat preference, describing the composition, and abundance. Chemical variables can help to have a better understanding of the conventional patterns, shaped by the habitat structure and physical variables. Habitat suitability index model for brown trout in three zones is completely different over the two years and this species could overcome these conditions. However, upstream areas were more appropriate. Dam, with decreases of outlet water temperature, also creates homogeneous and simple habitats leading to changes in expected fish distribution patterns with decreasing altitude. These conditions may have increased habitat suitability index for the brown trout in downstream, while despite favorable ecological conditions in the middle zone, habitat suitability index and alternative habitats available in this zone are likely to decline due to density and interspecific competition. The natural pattern of fish distribution and habitat selection varies along the altitudinal gradient due to various factors and human disturbances. Optimal management of protected areas can control the effects of some of these factors at least temporarily.

Socio-economic data of kilka fisheries in the south part of the Caspian Sea were collected using questionnaire form, which consisted of different variables related to the fishing activity to evaluate its socio-economic performance. The cost , livelihoods, employment and profitability, level of investments, debts, subsidies, activity levels, demographic and ownership structures data were employed and assessed.  The result of the analysis showed that 80% of the vessel owners were active in fishing operations in Mazandaran Province. This figure was 90% for the segment 12-18 LOA and 40% for the segment 18-24 LOA of Gilan Province. The survey also showed lower revenue and higher costs for the vessels that owner present onboard of the vessel during fishing operation.
According to the analysis, 377.4 crew were engaged onboard of all the vessel segments in both Provinces. Mean number of crew engaged on the board of each fishing vessel was 5.1 individuals. The number of different individuals engaged on kilka fisheries in both Provinces were calculated 480. The average working hours per crew for the kilka fleets in the southern Caspian Sea were calculated 1212.1 hours per year. The activity level (days at sea) for Mazandaran fleet was estimated 5485.8 days, which were higher than Gilan fleets. Daily duration of fishing trip for whole kilka fisheries was calculated 16.5 hours per day. Total yearly duration of fishing trip for whole fleets under study (2017) was 144108 hours. Personel costs were contributed 64%  of total variable costs of  kilka fleets, the lowest portion of the operational costs were belonged to energy cost . Whole kilka fleet in the Caspian Sea consumed total of 2.6 Million liters of fuel and oil in 2017. Each $US in 2017= 3885 Tomans (each Toman=10 Rials, Iranian currency).

The present study was conducted to determine the appropriate weight to release the hatchery produced fingerling of stellate sturgeon, Acipenser stellatus, into its natural habitat. For this purpose, prolactin and cortisol hormones, plasma electrolytes and osmolality as well as histological changes in the gill and kidney of stellate sturgeon transferred from fresh to brackish water at different weight (0.5, 1, 2, and 3 g) were assessed during a one-week time course. A total of 2400 fingerlings with different weights (0.5, 1, 2, and 3 g) were equally assigned into 24 aquariums, each one containing 200 L of freshwater or brackish water. After 24 hours, prolactin showed the highest concentration in 0.5 and 3 g fish groups kept in both experimental waters. Cortisol exhibited a time-dependent increase in the 0.5 g group in both experimental waters as well as the 2 g larvae kept in the brackish water. Generally, lower levels of Mg2+, Ca+2; K+, Na+, and Cl- were measured in the fish kept in freshwater aquariums. The lowest levels of osmolarity were found in the 0.5 g fingerling, especially those kept in the freshwater aquariums, whereas the highest levels were observed in 3 g groups in both experimental waters. Histological assessments illustrated that the volume of chloride cells in freshwater increased with increasing fish weight, whereas the cell count decreased. The same held true for glomerular capillary network size. Taken together, the evidence from this study suggests that stellate sturgeon fingerling less than 2 g are almost incapable to be transferred to brackish and saline environment, due to lack of kidney and gill development.

Size-dependent variation in growth, mortality, and recruitment over time are potentially controlled by changes in length -frequency distribution that is dependent to capture probability. The changes in the length-frequency distribution of ribbonfish, Trichiurus lepturus were studied along northern coasts of the Persian Gulf during the period 2008-2017. The length-frequency distribution of ribbonfish indicated the exploitation of larger sizes over the past decade. The mean total length was significantly smaller than the mean length recorded a decade earlier in 2008 (p<0.05). The length-weight relationship (WT=0.00004LT3.44) was found to be significant at 1% level of significance and indicated positive allometric growth.  The Von Bertalanffy growth parameters of all fish were =119.35 cm, K=0.3 year-1, and t0 = -0.38 year. Total, natural, and fishing mortality were estimated as 1.16 year-1, 0.53 year-1, and 0.63 year-1. The annual instantaneous rate of fishing mortality was higher than the target (Fopt= 0.26 year−1) and limit (Flim=0.35 year−1) reference points, indicating that the ribbonfish stock is at the risk of unsustainable exploitation.

Arthrospira (Spirulina) has been considered as an attractive microalgae in all aspects of human life including medicine, cosmetics, and food. Nitrogen source is an important cost-saving factor in large-scale cultivation. In the present study, the cultivation of S. maxima was studied by replacing the basic-nitrogen source of Zarrouk’s medium (2.5 gL-1) with concentration ranges of 0-10 gL-1 for sodium nitrate and 0-5 gL-1 for ammonium sulfate in terms of biomass and phycobiliproteins production. Biomass and phycobiliprotein growth of different nitrogen sources have shown different effects on growth. The changes in the amount of cell dry weight as a function of sodium nitrate did not show significant changes relating to its concentration. In case of ammonium sulfate, the cell dry weight of S. maxima without nitrogen source was 0.835 gL-1 during five days of cultivation. Moreover, phycocyanin and allophycocyanin contents were 0.053 and 0.072 mgL-1, respectively, while phycobiliproteins content and cell dry weight were decreased by increasing further concentration. There was a significant difference among the culture mediums containing ammonium sulfate and without nitrogen source in terms of concentration of biomass and phycobiliprotein. The highest and lowest results for cell dry weight and phycobiliprotein production were obtained from the treatment with nitrogen starvation and 5 gL-1 ammonium sulfate, respectively. Finally, nitrogen starvation was proved as a feasible way to grow and could be good candidate for biomass growth and phycobiliprotein.

The effect of different carbon sources in the biofloc system on growth performance, body biochemical compositions, digestive and hepatic enzymes of Nile tilapia was investigated in this research. Oreochromis niloticus fingerlings with average weight of 1.57±0.12 g were cultured for 37 days in fiberglass tanks (130 L), at a density of one fish per liter. The experiment was designed in five treatments including one control group and four biofloc treatments by adding different carbon sources: molasses (BFTM) and starch (BFTS) (complex carbon sources), barley flour (BFTB) and corn (BFTC) (simple carbon sources). Results showed the lowest dissolved oxygen (5.45 mg. L-1), pH (7.25) and feed conversion rate (0.99) in BFTS treatment (p<0.05), while the latter showed the highest protein efficiency ratio (2.91) and survival rate (98.2%). There were no significant differences in growth performance among various treatments (p<0.05).Somatic indices improved in biofloc treatments compared to the control group. Bioflocs formed in different carbon sources showed different nutritional value (p<0.05) which affected the quality of carcass analysis. The highest amount of amylase (95.86 U/mg protein) and protease (17.77 U/mg protein) activities were obtained in BFTB treatment and the lowest amount of hepatic enzymes activity was observed in the BFTS treatment (p<0.05). Generally, the present study showed that cultured tilapia using in situ biofloc produced by different carbon sources can promote FCR, survival, body composition, digestive and hepatic enzymes compared to the control group. Improved digestive activities are more noticeable in complex carbon sources and hepatic enzymes activities are stronger in simple carbon sources.

The present study was conducted with the aim of identification of macrobenthos in the Yekshabe estuary in Persian Gulf. Sampling of macrobenthos was performed from spring 2015 for one year. It was carried out seasonally by the Van Veen Grab (0.04 m2) at four stations, with three replications. The identified macrobenthos belonged to 51 families, 70 genera, 80 species, 4 classes (including Polychaeta, Malacostraca, Bivalvia, Gastropoda) and 5 Phyla. The average total density of macrobenthos was 760±614 per square meter. The most frequently observed classes of macrobenthos belonged to Polychaeta (67.8%), Malacostraca (18.5%), Bivalvia (11.6%) and Gastropoda (1.2%), respectively. According to the results of the Kruskal–Wallis test, there was no significant difference between the macrobenthos classes among the different sampling stations. The highest values of the Shannon-Wiener index of diversity (3.07) and the Margalef's richness index (4.66) were observed in spring, whereas the highest value of the Pielou's evenness index (0.95) was observed in autumn. The values of all indices at station 4 were the highest as compared to those of the others. The results of ANOVA test showed that the mean values of the indices were significantly different (p<0.05) in different seasons, whereas the mean values were not significantly different at stations.

Fish is a good source of protein; however, certain anthropogenic activities can contaminate their habitat with elevated heavy metals levels. In this study, copper, lead, mercury, cadmium, and arsenic in fish tissue, water and sediment were determined using PerkinElmer PINAAcle 900T Graphite AAS. Standard indices in human health risk assessment were used to estimate non-carcinogenic implications associated with consuming Clarias batrachus, Clarias gariepinus, Hemichromis fasciatus, Chrysichthys nigrodigitatus, and Macrobrachium rosenbergii from Densu River. Heavy metal concentration levels recorded in November 2017 were in the order of surface water < pelagic fish < benthic fishes < sediments. Cadmium and Lead levels in all investigated fish tissues exceeded FAO/WHO recommended standard. Pb, Cd, and Hg mean concentration levels in the water exceeded the WHO threshold level of 0.01, 0.003, and 0.001mg/kg, respectively. Concentration level of all sediment samples was below the USEPA set limit for analyzed heavy metals. From the correlation analysis, Hemichromis fasciatus was identified as an applicable bioindicator for assessing heavy metal pollution because it correlated with water and sediment significantly. Principal component analysis ascribed heavy metal pollution in Densu River to anthropogenic activities along the river. The interpretation of estimated daily intake computation showed that the content of individual heavy metals in the fishes is not likely to endanger the health of the consumers. However, the recorded hazard index for Clarias gariepinus, Clarias batracus, and Macrobrachium rosenbergii exceeded one (HI>1), an indication of a non-cancer risk to consumers.

In order to study the cannibalism behavior of Penaeus monodon post-larvae, the effects of four internal and external factors, such as individual size, post-larvae density (50, 80, 110, 140, 170 ind/L), food abundance and aeration, on the cannibalism rate were analyzed. The results showed that the cannibalism rate was significantly affected by individual size, post-larvae density and food abundance. When post-larval density increased from 50 ind / L to 110 ind / L，the average daily cannibalism rate increased by 358.07%. When larval density was more than 110 ind/L，cannibalism rate slightly increased. The average daily cannibalism rate decreased by 69.81% in 20 ind/mL food group than that of no-food group. The mix of individuals in different sizes could increase cannibalism rate significantly. Sufficient aeration could decrease cannibalism rate. The results indicated that insufficient food was a main reason to cause cannibalism in Penaeus monodon post-larvae. High stocking density and differences of individual size could induce and stimulate the cannibalism．

Benthic foraminifera are important in sediment production of coral reef environments and are excellent indicators of water quality and reef health. There is a lack of precise information about the foraminifer’s fauna of the coral reefs in the Persian Gulf. In this study, sediment sampling was performed in June 2019 from two coral stations of Naz Island and Zeytoon Park. The surface sediment with three replicates for each location was collected using a mini corer and then were fixed in 70% ethanol. In this study, thirty species belong to 23 genera and 19 families of foraminifer's assemblages were identified based on morphological characters. Our results indicated that Foraminiferal assemblages were similar in both sampling localities. Quinqueloculina was the most abundant genera for both Naz Island and Zeytoon Park. Foraminifer's frequency of Zeytoon Park was higher than Naz Island. Symbiont-bearing foraminifera (e.g. Peneroplis) were observed just in Zeytoon Park. Higher frequency and the presence of symbiont-bearing foraminifera possibly indicate that Zeytoon Park has a more favorable condition for the coral reef growth in the future. Finally, we recommend that the structure of the foraminifer’s community could be used as an early warning system for water quality around coral reefs and in particular, would help resource managers make better decisions about protecting coral habitats.

The increasing incidence of the harmful cyanobacterial blooms in mangrove ecosystem is a potential threat for aquatic organisms and their consumers. In the present study, we have evaluated the biodiversity of cyanobacteria and monitored their cyanotoxins. We isolated 120 bacterial isolates using BG11 medium from water and sediment samples collected from 10 stations throughout of the Khoor-e-Khooran mangrove forest at august 2018. Biodiversity and distribution pattern based on morphological characteristics showed that 10 cyanobacterial genera were spread over the studied area. Phormidium, Oscillatoria, Spirulina and Nostoc genera were dominated with frequency percentages of 25%, 20%, 10%, and 10% respectively. Analysis of 16S rRNA sequences showed that the strains have high similarity with type strains in NCBI GenBank ranged from 98% to 100%. Phylogenetic analysis proposed the non-indigenous origin of Microcystis strains because of their phylogenetic divergence. We detected microcystin gene in Microcystis sp. strain KH 3, Microcystis sp. strain KH 4 and Microcystis sp. strain KH 11, while nodularin and cylindrospermopsin gene were not detected in all isolated cyanobacteria. The extracted metabolites from KH 3 and KH 4 strains showed cytotoxicity with LC50 of 139.3 and 225.8 µg/mL against Artemia salina respectively. Their LC50 were 231.3 and 211.2 µg/mL against shrimp larvae respectively. They inhibited the proliferation of HUVEC cell lines with IC50 of 11.13 and 13.29 µg/mL and HEPG2 with IC50 of 15.49 and 12.51 µg/mL, respectively. Our results represented diversity and distribution pattern of cyanobacteria and demonstrated the incidence of microcystin in the Khoor-e-Khooran mangrove forest.