نشریه پژوهش های ماهی شناسی کاربردی
سال دهم شماره 1 (بهار 1401)

The aim of this study was the identification of morphometric and meristic characters and their diversity between males and females of Alburnus chalcoides in southern coast of the Caspian Sea in 2019. 160 specimens were caught randomly in 8 rivers leading to the Caspian Sea on the coast of Gilan (Anzali Wetland, Sefidrood River Basin, Allah Rud) and Mazandaran (Chalkroud, Cheshmeh Kileh, Mianroud, and Fereydoonkanaar River). All relative morphological and meristic characters were performed. The results of the t-test showed relative morphological and meristic characters between males and females, there was a significant difference in five morphological as well as in one meristic character. Examination of relative morphological and meristic characters between stations showed there was a significant difference in all indicators and this indicates the existence of different populations in different areas of the southern coast of the Caspian Sea. The coefficient of variation (C.V.) in morphometric characters is higher than meristic characters and shows the effect of environment on morphometric characters is more meristic characters. There was a significant relationship between logarithm weight and length. Irregular fishing of these fish in old age has caused the sampled age groups not to be more than three years old. And the highest frequency was related to the age group of two years. In the final conclusion, Morphometric characters have higher diversity than meristic characters and better performance in population separation, that indicates the high flexibility of this species for adaptation in different habitats.

The study was performed on the shape and morphology of otolith Grammoplites suppositus (Troschel, 1840) in Bushehr and Hormozgan waters of the Persian Gulf. 157 specimens (86 from Hormozgan and 72 from Bushehr) were collected as trawl bycatch. All the specimens are killed and fixed in 70% alcohol. After obtaining otolith, its shape indices include: form factor, roundness, circularity, rectangularity, ellipticity, otolith size index, otolith longitude index were examined by Image Measurement software. Then all the measuring indexes were analyses by Univariate and Multivariate analysis. In the analysis of otolith shape of the two regions, a significant difference was observed in most of the studied parameters. Also, differential population analysis such as MANOVA / CVA showed the existence of two separate populations in the study areas.

During 2018-2019, to study the morphological diversity of Oxynoemacheilus elsae, a total of 51 specimens were collected from the Godarchai, Barandozchai, Zarrinehrood and Mahabadchai rivers, Urmia Lake basin using electrofishing. From the collected samples, 22 morphometric characteristics were measured using a digital caliper with an accuracy of 0.1 mm. Also, in geometric morphometric (GM) method, the side of the samples were photographed, and 14 landmarks were digitized using tpsDig2 software. The extracted data were analyzed to understand morphological variation between the studied populations using multivariate analysis i.e. PCA, MANOCA /CVA and cluster analysis. The results showed a significant difference between the studied populations in terms of the morphological characters (P<0.05). In traditional method, there were significant differences in 10 traits between the studied populations (P<0.05). The main differences in GM method were related to the body and head depth, mouth position and caudal peduncle height. The observed morphological variations show the high adaptability of this species, especially in the pectoral fin length and body height traits with habitat adaptation.

The main of this study was to trac the local migration of common carp in the southern  of Caspian Sea by comparing the  composition of essential and non-essential amino acids in muscle tissue. Therefore, 26 samples of Common carp from the nets of  beach sein cooprative companies was evaluated on the southern shores of the Caspian Sea in the fishing areas of Golestan, Mazandaran and Gilan provinces and control samples from Sijwal (Golestan) and Shahid Rajaei (Sari) zones reproduction centers was prepared. Fish sampeling held in 2017 and 2018. Protein extraction was performed by Isoelectric Solubilization/Precipitation point. Total amino acids were analysed by high-performance liquid chromatography (HPLC). The results showed that the samples of the three provinces were separated in terms of amino acid composition and there are probably three carp populations in the western, central and eastern parts of the Caspian Sea, but migration with short distances takes place in the border part of the three provinces. Comparison of amino acid levels in males and females showed that in most cases in males it was more than females but it was not significant. Also,very high levels of lysine in muscle tissue of Golestan province and its proximity to breeding centers can confirm the role of artificial reproduction in the reconstruction of carp stocks in Golestan province. The results of some tests indicated the proximity of Gilan and Golestan fish groups, which could be due to human intervention in the transfer of finger fish to the two provinces.

This study aimed to investigate Growth modelling of the milk shark (Rhizoprionondon acutus Ruppel, 1837) from October 2019 until march 2021 for 18 months in northern waters of the Persian Gulf and the Oman Sea (Hormozgan Province). Overall, 317 shark samples of R. acutus including 137 males and 180 females were weighted. Results of the present work indicated that length-frequency distribution of both sexes were statistically different. Exponential relationship between total length and total weight of males and females were as W=0.0021L3.1508 and W=0.003L3.062 , respectively. After optimization by a non-linear regression through least square method, this relationship was obtained for males and females as W=0.0028L3.078 and W=0.0025L3.106, respectively. Males were estimated for the oldest age at 8 years with the length of 91.15 cm while females were estimated for the oldest age and tallest length at 10 years and 95.5 cm, respectively. By adoption of multi-modelling approach, the best model fittedd to indicate how to grow for the females of milk shark was Gampertz Growth Model (AIC=48.14, ∆AIC = 0). Logistic model had also a considerable protection to draw the growth of females according to AIC (AIC=50.02, ∆AIC= 1.87).  The best model fitted to show how to grow the males of milk shark was Logistic Model (AIC=36.33, ∆AIC= 0). Gampertz model had also a moderate protection to draw the growth of males (AIC=42.46, ∆AIC= 6.12), but three parameterized Von Bertalanfy model showed no efficneby to draw the gorowth of males (AIC= 53.2, ∆AIC= 16.86). . This study was performed for the first time on growth and mortality parameters of the milk shark in Iranian waters of the Persian Gulf and Oman Sea. Regarding the legal and illegal fishing pressure of this valuable species, this is recommended to apply the presented results for wider future studies as a basic study and to monitor its stock status with more precision annually, so as the managers can use these results to adopt scientific-management approaches for the protection of this precious species from extinction.

The fish's primary immune system in epidermis produces the mucosal layer as a surplus mechanism to cover the surface of the fish's body against infections. In addition to its physical functions such as reducing water friction and protecting against abrasion, it contains biologically active constituents, which is the first line of defense against pathogens. During the past years, the antimicrobial activity of various fish mucus has been studied. Due to the lack of information on sturgeon, in the present study, some properties of proteins in the epidermal mucus (Huso huso) as one of the native species of the southern coast of the Caspian Sea were evaluated. In this study, mucus was directly collected from fish surface in three different weight classes (0.4 , 4 and 40 kg) and some properties such as total protein concentration, chromatogram (RP-HPLC) and molecular mass profile of mucus proteins in three weight classes were compared. Antimicrobial activity of mucus was evaluated by disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The crude samples of different weights showed no significant difference in protein concentration (1.02 ± 0.03, 1.04 ± 0.01, 1.07 ± 0.02 µg/µl, respectively) but HPLC fraction No.4 in the third weight (40kg) showed a significant higher concentration in comparison to others (α=0.05). SDS-PAGE results revealed that the mucus samples contain peptides and proteins ranging from 5 kDa to 245 kDa with no considerable differences. All chromatograms showed similar numbers of fractions at similar retention time while the area percentage of fractions underwent significant differences in fractions 2, 4 and 9 (α=0.05). Disk diffusion showed the same antibacterial activity against A. hydrophila while group 1 (0.4 kg) had a significantly lower inhibition zone against S. iniae. All the samples possessed the same antimicrobial activity in MIC and MBC assays (MIC48=MBC48=25 µg). The current study revealed that all selected weight groups had the same properties in HPLC chromatogram and SDS-PAGE. Comparison of antimicrobial activity in MIC and MBC tests showed no significant difference between groups while in the disk diffusion test, there were significant differences in the antibacterial activity of weight groups exposed to S.iniaei, which could refer to the test competency. In conclusion, it can be claimed that in terms of protection (non-specific immunity), the first weight group (i.e. ≈ 0.4 kg) reached an evolutionary level as well as higher weights did (i.e. ≈ 4 and 40 kg).

Due to the emergence of nanotechnology and insufficient knowledge of the potential dangers of these particles on the one hand and the beneficial effects of probiotics on aquatic animals on the other hand, in this study the effect of emerging nano-silver contaminants with bacterial probiotic Lactobacillus as a dietary supplement Some liver indicators in common carp were discussed. The fish were subjected to 6 experimental treatments and after 42 days of feeding with probiotics based on lethal toxicity test and sub-lethal according to OECD standard method, they were exposed to nanosilver for 4 and 10 days, respectively, with adaptation. At the end of the lethal toxicity test, liver tissue samples were extracted from the fish and hepatic histopathology indices were evaluated. Nano-silver alone caused structural abnormalities including deformation and necrosis, bleeding, swelling and dehydration, as well as lateralization of the nucleus in the liver. Probiotics alone drastically reduced the amount of these side effects. Also, the combined use of probiotics and nanosilver, although associated with increased bleeding, stimulated nonspecific immunity in common carp and improved other liver complications.

The purpose of this study was to survey the effect of dietary fish oil replacement with different levels of soybean lecithin on growth performance and digestive enzymes activity of Persian sturgeon. Three hundred and sixty fish with average weight of 85 ± 0.09 g were treated with 6 experimental diets and three replicates, containing 0, 2, 4, 6, 8 and 10 percent soybean lecithin for 10 weeks. Based on the biometry at the end of culture period, the highest weight gain, final weight, length and specific growth rate were present in the 6% dietary fish oil replacement with soybean lecithin treatment, which showed significant difference with other treatments (P≤0.05). There was no significant difference in condition factor between different treatments. The lowest FCR value was observed in treatment 4 which showed a significant difference with other treatments (P≤0.05). Digestive enzymes activity such as lipase, pepsin, chymotrypsin, and amylase did not show any significant differences between different treatments, however trypsin exhibited significantly higher activity in treatment 4 ( 6%lecithin) compared to fish treated diets with 0% (control) and 2% fish oil replacement with lecithin (P≤0/.05). It can be concluded that replacement of fish oil up to 6% with soybean lecithin in A. persicus diet improves weight gain, final weight, specific growth rate, food conversion rate and trypsin activity significantly.