Iranian Journal of Fisheries Sciences
Volume:18 Issue: 3, Jul 2019

The ionic contents, pH and osmolality of seminal plasma and their relationships to sperm motility indices (sperm motility duration and percentage of motile sperm) were evaluated in bester. Semen was collected from six bester specimens and their seminal plasma was evaluated. The seminal plasma contained 54.5±2.8 mM sodium, 22.33±2.5 mM chloride, 7.1±1.2 mM potassium, 3.55±0.6 mM calcium and 0.58±0.09 mM magnesium. The result shows that Na+, Cl- and K+ (54.5±2.8, 22.33±2.5 and 7.1±1.2 mM, respectively) were predominant ions in bester seminal plasma like other sturgeons. However the concentrations of K+, Ca2+ and Cl- in bester seminal plasma were higher than those reported in beluga and sterlet as parental species. The mean pH and osmolality of seminal plasma were 8.09±0.34 and 127.6±20.8 mOsm kg-1, respectively. A significant negative regression was observed between osmolality and percentage motility (r=- 0.893).

Acipenser stellatus (stellate sturgeon) that has been intensively captured for decades represents a sturgeon species of great importance for the scientific community and fishermen. Besides overfishing and poaching, their reproduction sites have been destroyed and their natural habitats were affected by pollution. In consequence, wild populations of stellate sturgeon have decreased dramatically and this species is being considered critically endangered. In order to conserve this species, efforts have been made to artificially reproduce native sturgeons and restock natural habitats with the broodstock. The analysis of genetic diversity of the future breeders is of great importance in order to avoid the inbreeding depression and genetic drift. Six aquaculture strains of A. stellatus reared in fish farms from the South of Romania were genetically analyzed. The assessment of the genetic diversity was made by using DNA markers, such as cytochrome b mitochondrial gene and microsatellite nuclear loci. The results showed a moderate genetic variability within the strains and a moderate genetic diversity between the strains. One strain was slightly inbred and is recommended not to be included in the reproduction programs. In conclusion, five out of six aquaculture strains were genetically distinct and can be used in selective breeding programs aimed to conserve stellate sturgeon from the Lower Danube River.

This study was carried out to investigate the effects of starvation and feeding regimes on growth performance, haematological and biochemical parameters of blood and body composition of Caspian brown trout parr. For this purpose, 900 fish (average weight: 12.5±1 g) were stocked in 300-l tanks (18 tanks at a stocking rate of 50 fish in each tank) using an open system. Six experimental groups composed of feeding and starvation regimes were considered for the experiment as follows: FFF (Six weeks feeding), SSS (Six weeks starvation), SFS (Two weeks starvation + two weeks feeding + two weeks starvation), FSF (Two weeks feeding + two weeks starvation + two weeks feeding), FS (Three weeks feeding+three weeks starvation), and SF (Three weeks starvation + three weeks feeding). According to results obtained, the growth rate (GR), special growth rate (SGR), condition factor (K) and hepatosomatic index (HSI) decreased as the length of starvation periods increased (p<0.05). The haemoglobin content and haematocrit did not seem to be affected by starvation (p>0.05) while the highest values of red blood cells (RBCs) and white blood cells (WBCs) were observed in the SSS group (p<0.05). Also, the lower values of MCH (haemoglobin concentration in one RBC) and MCV (mean volume of one RBC) were observed in the SSS group (p<0.05). The lipid content of body tissue decreased with increased length of the starvation period (p<0.05), wherase the total protein, ash and moisture showed no differences between the experimental groups (p>0.05). In conclusion, our results showed that starvation has significant physiological and morphological effects on Caspian brown trout parr.

The success of many vaccines relies on their association with selected adjuvants in order to increase their immunogenicity and ensure long-term protection. Propolis is a natural compound, mostly known for its immunostimulatory properties. In this study the adjuvant effects of propolis in combination with formalin-killed Aeromonas hydrophila vaccine in Common carp (Cyprinus carpio) were evaluated and compared with Freund’s adjuvant. Three hundred juvenile carp (weighing 50.4±3.2 g) were divided randomly into four groups in triplicates. The fish were intraperitonealy injected with A. hydrophila bacterin (A.h) in combination with normal saline (Formalin Killed Bacterin, FKB group), Freund (FKB +F group), and Propolis (FKB +P group) respectively. The control group was injected with normal saline.  Serum samples were taken from fish in each group every other week (days 0, 14, 28 and 42) of the experiment and immunological parameters including anti A. hydrophila antibody titer, serum lysozyme and antibacterial activity, complement activity, Nitro blue tetrazolium activity and serum total protein and globulin were compared among the groups. At the end of study the remaining fish in each group were challenged with virulent A. hydrophila and mortality was recorded for 10 days and Relative Percentage Survival (RPS) was calculated and compared among the groups. Results showed that although antibody titer and most of none specific immune responses increased in groups 2 and 3 compare to control group (p<0.05), no significant difference were seen in group 1 and 3 (p>0.05). Besides no significant change was observed in mortality rate following the challenge in the propolis adjuvanted group compared with the FKB group (p>0.05). According to results, it can be concluded that although propolis as an adjuvant can promote some immune responses of common carp, it can't affect efficacy of vaccine and Ab titer of injected antigens, so it seems more work is needed to present propolis as a proper candidate for the development of a natural adjuvant in fish vaccines.

A feeding trial was conducted for sixty days to determine the effect of dietary Aloe vera on parameters related to growth rate, health status and hematological parameters of shirbot (Tor grypus). Two hundred and forty fish weighing 50-60 g were randomly subjected to four different treatments, including a control, T1 (0.1% of A. vera), T2 (0.2%) and T3 (0.5%) in triplicate. Hematological parameters and some growth parameters, including the body weight, total length, condition factor, feed conversion ratio, feed efficiency, specific growth rate and protein efficiency ratio were measured. Administration of fish to different concentrations of A. vera extract led to significant (p<0.05) increase in total erythrocyte count, packed cell volume, and hemoglobin when compared with the control group. Mean corpuscular hemoglobin concentration were increased only in T2 and T3 in comparison with the control. When animals received 5% of A. vera daily, they showed a significant increase (29%) in white blood cells (p<0.05). Growth parameters were improved with the addition of different concentrations of A. vera to fish food. According to the results obtained, it might be concluded that feeding this species with A. vera extract could likely enhance growth rate and also hematological parameters.

The chemical compositions, antioxidant and antimicrobial properties of fucoidan extracted from Sargassum ilicifolium and S.angustifolium were investigated. The results showed that these seaweeds were characterized by an acceptable level of minerals and proteins. The fatty acid profile was dominated by the palmitic acid, which represents about 37.44±0.01% and 23.05±0.01% of the total fatty acids, followed by oleic acid (13.83±0.01% and 45.30±0.01%) for S. ilicifoliumand S. angustifolium, respectively. Swelling capacity, water holding capacity and oil holding capacity were varied in two different temperatures (25◦C and 37◦C).The antioxidant activities of fucoidan including DPPH, superoxide-hydroxyl radical scavenging, chelating ability and reducing power were considerable. The correlation of sulfate and phenol contents with scavenging superoxide radical ability, chelating ability and reducing power was positive. The antibacterial activity was evaluated by disc diffusion method against Bacillus subtilis and Staphylococcus aureus (gram positive bacteria) and Escherichia coli and Salmonella enteritidis (gram negative bacteria). There were no positive results against gram negative bacteria. In the concentration of 5 mg ml-1 small clear inhibition zones was observed against B.subtilis and S.aureus. On the basis of obtaining results from antioxidant activities, fucoidanis suggested as potential natural and safe antioxidant agents in the nutraceutical industry.

The present work deals with the study of fish larvae of coral reef fishes in the Red Sea (Hurghada). It was aimed to study the spatial and temporal variations of fish larvae for management purposes. Sampling stations were chosen at Marina, Sheraton, Magawish and Arabia. The samples were taken monthly throughout the period of the study from August 2014 to July 2015 using plankton nets of different mesh sizes (150, 350, and 500 micron). The highest density of larvae was observed in July when 841 larvae 1000m-3 were collected whereas, the lowest density was recorded in March and October at 11 1000m-3. The highest number of species was recorded in Sheraton with 28 species followed by Magawish with 27 species recorded followed by Marina with 26 species recorded while the lowest was recorded in Arabia with 25 species. Concentration of larvae was significantly different between months and sites. There was a significant difference in the number of species between months but not between stations. Larvae of mullid fish were abundant in summer while larvae of clupeids were observed all year round.

The proximate composition, amino acids and fatty acids composition in the muscle of wild, inshore and offshore cage-cultured large yellow croaker, Pseudosciaena crocea (Richardson, 1846), were determined to identify nutritional differences. Wild fish groups showed highest content of moisture and crude protein, but the lowest lipid content. Offshore cage-cultured fish showed significantly higher content of moisture and crude protein content, but lower crude lipid content than inshore cage-cultured fish. The content of aspartic acid, glutamic acid, and alanine was higher in wild large yellow croaker than inshore cage-cultured groups, but similar to offshore cage-cultured fish. Significant lower contents of total amino acids, essential amino acids, non-essential amino acids and flavor-enhancing amino acids content were recorded in two cultured fish groups than those in wild group. While no major differences in fatty acids composition were found between wild and cage-cultured groups except for linoleic acid. The fish from offshore cages has much better nutrient profile than inshore cage-cultured fish, but was still inferior compared to wild fish.

This study was performed to investigate the effects of feeding rates on growth performance, feed conversion and body composition of juvenile snow trout (Schizothorax zarudnyi). For this purpose, fish with an initial body weight of 2.17±0.1 g were fed a commercial diet (40% protein, 3.8 Kcal g-1 diet) at five ration sizes of 2%, 4%, 6%, 8% and 10% of their body weight per day, for 60 days. The feeding trial was conducted in triplicate. Maximum weight gain, best feed conversion ratio (FCR), best specific growth rate (SGR %), highest energy retention (ERE %) and protein efficiency ratio (PER %) were evident for rations of 4–6% body weight. Second-degree polynomial regression analysis for PER, FCR and ERE indicated the break-points occurred at 4.9, 5.1 and 5.2% BW day−1, respectively. Maximum body protein content was obtained for 4% and 6% rations. Body moisture, fat and ash content remained unchanged. Based on the above results, it may be concluded that the 4.9-5.2% body weight per day ration is optimal for the growth, conversion efficiencies and body composition of juvenile S. zarudnyi and it entails favorable economic benefits.

Using phytobiotics as fish feed additives has interestingly increased during the recent decade. The aim of the current study was to evaluate the effect of individual and combined levels of thyme and vitamin E in common carp. Juveniles were separately fed four distinct diets including a control diet (commercial diet without any additive), a diet supplemented with 1% ground Shirazi thyme, diet supplemented with 100 mg/kg vitamin E and a mixture of Shirazi thyme and vitamin E (TE) with mentioned concentrations for 45 days. Sampling was done on days 15, 30 and 45 after the feeding trial duration and some growth and plasma biochemical parameters were evaluated. The individual thyme supplementation significantly increased weight gain (%), feed conversion efficiency and decreased feed conversion ratio (p<0.05). Plasma enzymes (AST, ALT, ALP and LDH) were not affected in all experimental groups. Compared with the control, triglyceride and glucose were significantly elevated in TE complex at all sampling times. Plasma proteins (total protein, albumin and globulin), cholesterol and creatinine were not altered in all treatments. In conclusion, dietary supplementation with individual 1% Shirazi thyme had no harmful effects on plasma biochemical parameters and increased growth performance of the fish. Moreover, positive effects of thyme on fish growth were more than with vitamin E. Supplementation with a mixture of vitamin E and thyme also displayed no superiority than the individual use of Shirazi thyme in the diet.

The aim of this study was to assess the eutrophication and trophic status of the Caspian Sea based on different indices and also compare its status with the reference threshold values in the Iranian coastal waters of Caspian Sea (hereafter ICWCS). The water samples (three replicates) were collected along four transects (off the coast from Anzali, Tonekabon, Nowshahr and Amirabad) between spring 2013 and winter 2014. The results show marked significant differences between the mean concentrations of DIN, TP, DO and Chl-a in different seasons (p<0.01) and high significant correlation with different indices in the ICWCS. The mean of Trophic Index of Vollenweider (TRIXvollen.), Trophic Index of the Caspian Sea (TRIXcs) and Technique Quartile Range of Trophic Index (TQRTRIXCS) values ranged from 4.43 to 5.05 (good, high eutrophication risk), 5.21 to 6.00 (moderate, high eutrophication risk) and 0.58 to 0.95 (moderate to high) in different seasons for these three indexes, respectively. The results of nutrients and chlorophyll-a concentrations at the four sampling locations when compared with the reference threshold value indicated that the trophic status of this ecosystem changed from oligotrophic to mesotrophic/meso-eutrophic in 2013-2014. All there indexes (TRIXcs, TQRTRIXCS and Reference Threshold Value methods) produced similar results and therefore, could be used interchangeably for the study area.

Otoliths are considered as very useful structures of fishes for various studies. This investigation aimed to compare the morphometric parameters between the right and left otoliths of male and female specimens of four species of the fishes belonging to the family Carangidae from the northern Persian Gulf. The morphometric parameters such as weight, length, width, area and perimeter of sagittal otoliths were measured and compared between males and females. The relationships between otolith morphometric parameters (length, width, weight) and fork length were also examined. According to the results from independent sample t-test, significant differences were found in length, width, and area of otoliths between males and females of Carangoides malabaricus, whereas no significant differences were found for three other species. The otolith weight of Carangoides coeruleopinnatus and Megalaspis cordyla were significantly different between left and right otoliths (p<0.05).  Likewise, significant differences were found in the otolith area of the right and left otoliths of Carangoides. coeruleopinnatus (p<0.05). Furthermore, no significant differences were found in the shape indices including form factor (FF), roundness (RD), aspect ratio (AR), circularity (C), rectangularity (R) and elipticity (E) between the right and left otoliths. The results suggest that the length and weight of sagittal otoliths are likely suitable indicators for fish fork length in all studied species.

A 15-day study was conducted to evaluate the effects of Artemia metanauplii enriched with two commercial supplements (Easy DHA-Selco and S. presso) which contained high levels of n–3 long chain polyunsaturated fatty acids (n–3 LC-PUFA) on growth performance, stress resistance and fatty acid profile of Litopenaeus vannamei post larvae (PL). In this regard, PL were fed with three different types of Artemia including: (1) newly hatched Artemia franciscana nauplii as the control group; (2) Artemia metanauplii enriched with Easy DHA-Selco; and (3) Artemia metanauplii enriched with S. presso. Survival rates did not change among different groups. PL fed Artemia enriched with the S. presso and the Easy DHA-Selco showed the highest wet and dry weight, respectively (p<0.05). Moreover, PL fed Artemia enriched with the commercial emulsions had higher survival rate (~ 10 %) than treatments fed newly hatched Artemia (p<0.05).The concentration of n–3 PUFA especially DHA and also n-3 / n-6 PUFA ratios were higher in PL fed with Artemia enriched with the commercial emulsions than the control group. Feeding enriched Artemia with n–3 LC-PUFA is recommended to improve growth performance in larval stages of L. vannamei.