جستجوی مقالات مرتبط با کلیدواژه « caspian sea » در نشریات گروه « شیلات »

The stock status of most fisheries resources is not well-known, which is associated with limited data available for stock assessment. To overcome this gap, several data-limited stock assessment models, including the surplus production model, were applied to estimate stock status of these data-limited resources where no sufficient data is available to apply the conventional stock assessment models. To estimate MSY, catch and CPUE data for Cyprinus carpio caught from the southeastern Caspian Sea were applied. Twenty-two years data (1999-2022) were analysed by SPM to estimate MSY. Three parameters including population growth rate (r), population carrying capacity (K), and initial biomass for an exploited population (Binit) required for estimating MSY were guessed 0.075 (/yr), 6952 tones, and 3500 tones, respectively by the catch-MSY model. The estimated MSY using these guessed parameters by SPM was 130 tones. While, estimated MSY using the repeated (multiple) starting points was 1320 tones. Phase plot indicated that the current status was both below the limited and the target biomass reference points. These illustrated the stock of C. carpio in the southeatern Caspian Sea is unsustainable and overfished. Since, survival of C. carpio depends the releasing hatchery reared juveniles to the wild, specific fisheries management should be applied to prevent the undersize catch and illegal fishing.

This study used a dynamic model to predict the fishing status of the Persian Sturgeon (Acipenser persicus) along the coast of the Golestan province in the Caspian Sea. The findings indicated that based on the initial population in 2017 equal to 2500 samples of fish if harvested at the current rate, the stocks of this valuable sturgeon fish will be destroyed in the next 50 years. However, when considering the harvest rate of 0.2 per year (nearly half of the current catch), the amount of fish harvested will increase so that this stock will completely regain its ability to regenerate itself.

This study examines the characteristic of microplastics (MPs) in sediments collected from the coastal areas of the southern Caspian Sea, Mazandaran province (Babolsar and Sari cities). Twelve sites for sediment sampling selected during 2022. MPs identification detected primarily under stereomicroscope and then ascertains and discovers their polymer composition by ATR-FTIR. The results showed that Babolsar areas, with 5 meters far from the shoreline, had the most abundance (660±165.15items/Kg). On the other hand, Sari station with 500 meters far from the shoreline contained the least MPs (220±81.33). Average number of detected MPs in all samples was 406.66±161.33. Fibers (80.33%) were the most abundant MPs, whereas films (3.28%) detected the least. In the case of size, the range of 1000-3000µm showed the most abundant MPs (39.34%) and MPs less than 2 µm the least ones (4.10%). Gray and black (50.82%) was the dominant color and yellow (3.28%) was rarely detected color (3.28%). Polymer constituent of examined MPs includes: (PET: 30%); (PS: 20%); (PA: 20%); and (PP: 15%). The findings of this study revealed that MPs occurrence in coastal sediments distribute from several sources; including tourism as well as wastewaters and packaging. These activities cause entering plastic litters along the coastal areas and their degradation accelerated t MPs distribution.

This work aimed to compare hybrid and non-hybrid populations of Hircanian goby (Ponticola hircaniaensis) from two rivers, Kabudval and Shirabad, Golestan Province, respectively. For this purpose, 20 morphometric characteristics were measured. To reveal the morphological differences between the studied populations, the morphological characteristics after standardization were analyzed using Discriminant Function Analysis (DFA) and Non-parametric Multivariate Analysis of Variance (NPMNOVA) based on the P-value obtained from the permutation test with 1000 repetitions. The results of Kruskal-Wallis's test showed that out of 20 morphometric characteristics, 11 traits significantly differ between the two populations. Also, the results of DFA analysis based on the permutation test with 1000 repetitions showed a significant difference in morphology between the two populations of Kabudval and Shirabad rivers (P = 0.048). Since the habitat conditions of the two rivers, Kabudval and Shirabad, both forest streams, are almost identical, the morphological difference between these two populations of Hircanian goby can probably be due to the genetic difference due to hybridization.

The purpose of this research was to evaluate the consumer’s behavior of farmed carp in the north of Iran (Golestan, Mazandaran and Gilan province).

After defining the assumptions and designing the analytical-conceptual model based on the theory of planned behavior, a suitable questionnaire was developed and completed by the statistical community. In order to evaluate the intensity of the relationship between the research variables and the model elements, as well as to check the acceptance or non-acceptance of the assumptions, the structural equation modeling method (SEM) was used.

Per capita fish consumption of farmed carp consumers is 5.3 kg. Of this amount, 400 grams are canned, 600 grams are consumed in restaurants and outside the home, and 2.5 kg are consumed at home. Per capita consumption of their farmed carp is 1.4 kg, so half of their consumption is from other fish.In this research, all hypotheses were confirmed, In this way, the effect of perceived usefulness, perceived risk and quality on attitude, the effect of normative beliefs, moral obligation and household income on subjective norms, the effect of control power, control belief, experimental records, advertising and education on the perceived behavior control, the effect of attitude, subjective norms and perceived behavior control on the decision to buy farmed carp and the effect of the decision to buy and perceived behavior control on the final behavior were reported to be significant (p<0.05). The values of the effect coefficients showed that the most effective variable on the attitude, subjective norms and perceived behavior control, is quality (with an effect coefficient of 0.46), income (with an effect coefficient of 0.44) and experience records (with an effect coefficient of 0.37), respectively. Also, among the three main elements of the model, the attitude had the greatest effect on the decision to buy and consume farmed carp (with an effect coefficient of 0.48).

The ability of fish adaptation to different salinities depends on osmotic, ionic and biochemical regulation, on the other hand, transferring fish to salt water causes the development of their osmotic and ionic homeostasis mechanism. The adaptation of stellate sturgeon (Acipenser stellatus) in four weight treatments including 0.5-1, 1-3, 3-5 and 5-10 g in water with four salinity levels of 0.5, 4, 8 and 12 g/l during 8 phases and each experiment was performed in 4 predicted treatments. Each experiment was carried out in a period of about one month along with feeding with live foods, preferably gammarus, Nereis worms, and chironomidae larvae at the saturation level of 6 times a day, as well as daily siphoning and water changes. Osmolarity and factors of chloride, calcium, sodium and potassium were measured in fish blood serum. In the examination of the compatibility and adaptability of this fish with the conditions of changing salinity, the results showed that with increasing salinity, the levels of potassium, sodium, chloride and blood osmolarity increased. The stellate sturgeon are able to adjust the osmotic pressure and ionic composition of their blood serum when they migrate from hyperosmotic to hypoosmotic environment or vice versa. The blood osmolarity of fish with a weight of 5-10 g was higher than other weights, and the lowest osmolarity was observed in fresh water (0.5 g/l). The results of this study showed that the amount of potassium in the blood serum decreased with the passage of time and the increase in salinity, and increased the amount of sodium and calcium in the blood serum.

More than 50 fish species exist in Guilan coast waters and 20 species of them are economic, but there is few data about their fingerlings. This study has been done in Talesh, Anzali, Kiashahr and Chaboksar shores and fish seasonally caught by beach seine with 8 mm mesh size from winter to autumn 2021, and the main purpose was determining fish abundance in Guilan province coasts, too. Results showed 32 fish species belong to 13 families in studied are and Leuciscidae family was the most diversified with 8 species. The study of fish abundance showed dominancy of Chelon saliens, Alburnus chalcoides and Atherina caspia with 42.5%, 18.1% and 11.6% in Talesh shore, A. chalcoides, C. saliens, and A. caspia with 25.1%, 22.1% and 20.8% in Anzali shore, C. saliens, Rutilus frisii and A. chalcoides with 31.8%, 17.4% and 14.8% in Kiashahr shore and C. saliens, A. chalcoides, Neogobius pallasi and chelon auratus with 29.9%, 21.5%, 14.2% and 10.5% in Kiashahr shore, of total count (number), respectively and they were predominant. In general, were abundant fish, the fingerlings to non-adults of sharp-nosed grey mullet (Ch. saliens) and Shemaya (A. chalcoides) in all stations, Caspian silverside (A. caspia) in 2 stations and fingerlings of Golden grey mullet (Ch. auratus) and Kutum (R. frisii), and fingerlings to adults of Caspian sand goby (N. pallasi) in one station, that show a more adaptation of these species to environmental conditions in 4 studied stations. The continuous monitoring of density of small size individual of fish species in southern coasts of Caspian Sea is essential for conservation of their populations.

More than 70 millions of Kutum (Rutilus frisii) fingerlings are released in the rivers of Guilan province annually for restoring, but there is few data about biological chracteristics about the fish during staying in the rivers downstream, thus this study has been done on abundance, growth, condition factor and diet of released fingerlings of kutum fish (Rutilus frisii) in Khoshkrud River downstream, and for this propose, 3 stations selected in the river downstream and sampling has been done using electroshocker monthly from Oct. 2022 until March 2023. Results showed Alburnoides samii, Capoeta razii, Rutilus frisii, Ponticola gorlap and Cobitis with 249.2, 108.7, 85.2, 32.2 and 31.4 individuals in 100 m2 catch effort had the most abundant. The fingerlings of kutum fish present in all months in the river downstream and its density varied 20.0 to 212.5 individuals per 100 m2. Studied fingerlings (n=119) had a weight of 2.10-15.10 (5.77±2.54g, average±s.d), total length of 6.62-12.20 (8.61±1.13cm) and condition factor 0.71-0.97 (0.86±0.05) and there was significant statistical difference only in condition factor between autumn and winter. The length-weight parameters was calculated for b-value 3.09 and correlation coefficient (r2) 0.98 and indicated isometric growth patterns. It was determined vacuity index 40.9% and 59.6%, the mean relative length of intestine 0.78±0.08 and 0.75±0.08 and the mean fullness intensity 76.1±97.1 and 71.3±118 in kutum fingerlings in autumn and winter seasons, respectively. There was 6 macro-invertebrates and 14 genera of algae in gut of kutum fingerlings and in the fish intestine were abundant Chironomidae from benthos and genera Synedra, Navicula, Diatoma and Melosira from algae cells in both seasons. In general, fullness intensity, condition factor and water temperature were no suitable for staying fish fingerlings in the stuied duration, but was not distinguished the reason of settle of fish in rivers and no emigration to sea water.

This research was carried out in order to determine the length and age composition, calculate growth and mortality parameters and calculate the biomass of golden gray mullet in the Iranian waters of the Caspian Sea during the year of 2022-2023. The biometric data were collected from beach seine fishing cooperatives in the Guilan, Mazandaran, and Golestan provinces. The mean (± SD) fork length and total weight were measured at 29.9±4.8 cm and 305.7±143.0 g, respectively. The age range was 2 to 11 years, and more than 74.4% of the age group were 3 to 4 years with the mean (± SD) fork length of 26.3±5.1 and 31.3±5.6 cm, respectively. In the relationship between fork length and total weight, the values of a and b were calculated as 0.018 and 2.836, respectively, with a correlation coefficient of 0.97. Growth parameters, including the von Bertalanffy growth equation constants (K, L∞, and t0), were determined as 0.14 (/year), 64.0 cm, and -1.02, respectively. Mortality parameters, encompassing total mortality (Z), natural mortality (M), and fishing mortality (F), were calculated as 0.95, 0.30, and 0.65, respectively. The biomass of golden gray mullet was determined 12155.5 tons. This research provides valuable information in the direction of sustainable management and protection of golden gray mullet stocks in the Iranian waters of the Caspian Sea.

The study is Considering the importance of the role of benthic communities in evaluating the ecological status of aquatic ecosystems and part of a research project in the southern coasts of the Caspian Sea (depths less of 30 meters) was conducted in 2019. The aim of this study was investigation of the distribution, density and biomass of macrobenthos organisms in the water at a depths of 5, 10 and 30 meters south Caspian Sea. Sampling was seasonaly at eight with using Van Veen Grab. Overall 34443 organisms of Polychaeta including 3 families, 4 genuses and 4 species. The results showed that the highest density at Sefidrood station with mean of 327±27.71 N/m2 and lowest was at Bandartoraman station with mean 77±5.33 N/m2. The highest of Polychaeta was in summer and depth 30 meters with mean 285±26.18 N/m2 and lowest density in spring and depth 10 meters with mean 38±10.81 N/m2. The highest biomass was in spring and depth 30 meters with mean 0.23±0.02 g/m2. The highest species was assigned to S. gynobranchiata with mean 352±19.74 N/m2 and frequency 80%. In general, the results showed that in most seasons of the year, S. gynobranchiata was the dominant Polychaeta species.

Samples caught by beach seine nets in the fishing season of 2019-2021 in the southern costal zones of the Caspian Sea were used to study reproductive biology of Cyprinus carpio. Totally, 435 sea carp, including 237 female and 198 male were sampled, and their age and maturity stages were determined over sampling period. The results indicated that age range of the sampled C. carpio varied from 1 to 6 years in males, from 1 to 9 years in females, and from 1 to 9 years in combined sexes. The highest frequency of samples was in the age group of 1 for males (54.4%), 2 for females (34%), and 4 years for combined sexes (26.6%). Frequency of fish observed in the V and VI maturity stages was 45.14% and 27.17%, respectively. According to the frequency of different maturity stages and also the trend of changes in Gonado-somatic index (GSI), two spawning peaks were observed in C. carpio, including weak peak occurred in December-January and strong peak observed in March-April. The female mean length at sexual maturity (Lm50%) was 27.7 cm. Absolute and relative fecundity (mean ± SD) of C. carpio were 429310±233479 and 668±319 eggs, respectively. Since, there was an overlap between the spawning peak of C. carpio and beach seine fishing period for bony fish, it is proposed that fishing season to be banned at the beginning of April.

This study investigated the Caspian Sea surface temperature fronts from 2015 until 2019 using satellite images (MODIS). The sea surface temperature front, a narrow-width area with a high-temperature gradient, plays a crucial role in various biological, chemical, physical, and agricultural parameters and climate change issues. Detecting sea surface temperature fronts also helps understand other phenomena such as upwelling, eddy, and biological accumulation. The Canny algorithm was used in the MATLAB environment for detecting the fronts, and the results were compared spatially and temporarily. It was observed that the fronts in the north of the Caspian Sea are permanent from September until November and March until May, while they are impermanent and dashed at other times of the year. In the east of the south Caspian Sea, the only detected fronts in March repeat annually, whereas in the west of the south Caspian Sea, fronts were detected in all months except for August, consistently over the five years. The pattern of temperature fronts in the east and west of the Middle Caspian Sea differs. The fronts are clustered in winter but become coherent and clear in summer. Additionally, the southern Caspian Sea temperature fronts are less abundant in the pre-summer period than in other periods. The Caspian Sea surface temperature fronts were mostly detected in the location of internal waves, steep areas near the coast, and eddies.

Natural habitats around the world have suffered a lot of pressure due to the increase in human industrial activities in order to achieve economic-welfare goals, by changing in the climate system, and the consequences of this event include the extinction of species and the reduction of biodiversity on a global scale. In this regard, the evaluation of the threats resulting from the changes created in the ecosystems will be pivotal to their management and conservation. In this study, the distribution of Rutilus kutum was predicted under two optimistic and pessimistic scenarios of 2050 and 2080 by Maxent model. In this study, the set of data collected by the authors and various available scientific sources from a period of 50 years (1970 to 2020 AD) was used. Also, the environmental and climate variables used in the modeling were extracted and prepared from www.worldclim.org.The results showed that the performance of the model in predicting species distribution was excellent (0.946) based on the AUC (Area Under the Curve) criterion. In addition, it is predicted that the distribution of the species is likely to decrease significantly in all years and optimistic and pessimistic scenarios. Therefore, considering the importance of the sim species in the food basket and its positive effect on the livelihoods of local communities, reducing its distribution in the future could be considered a threat to food security. In conclusion, the protection of this species requires urgent planning, actionable decisions and effective measures regarding the preservation and restoration of rivers, controlling the negative effects of climate change and efforts to reduce the accelerating factors of this critical phenomenon.

In this study, some aspects of the reproductive biology of Caspian Roach caught by beach seining were investigated along the southeast coats of the Caspian Sea in the period of 2019-2021. From a total of 317 samples of caught fish (144 males and 173 females), the sex ratio of male to female was 1:1/2, which was not statistically significant with the expected ratio of 1:1 (p>0.05). The average fork length (± standard deviation) was 15.6 ± 2.63 cm (with a range of 10.6-25.5 cm) for males and 18.7 ± 3.70 cm (with a range of 11.3-32-5 cm) for females. The range and average weight for males were 18-214 g and 60.7 ± 36.20 g, respectively, and 22-502 g and 120.5 ± 74.76 g for females, respectively. The minimum, maximum, and average absolute fecundity of R. caspicus were estimated as 6707, 51438 and 18773 ± 9800 eggs, respectively. The mean relative fecundity was estimated to be 152 ± 33 eggs/g and 967 ± 367 eggs/cm in relation to the total weight and fork length, respectively. The absolute fecundity of the species increased with an increase in the length and weight of fish with coefficients of determination of R2= 0.62 and 0.68, respectively, so that the range of fecundity in the length range of 14.5-15.5 cm is equal to 6707-11807 eggs and in the length range of 27-32 cm was estimated as 35813-42693 eggs. According to the results, sexual maturity at stages IV and V is present in all sampling months for females of R. caspicus. The mean length (fork length) at first maturity (Lm50%) of females R. caspicus was 13.8 cm. The highest value of Gonadosomatic index (GSI) for males was observed in February with a value of 7.08, and for females in March with a value of 16.06 which decreased to 15.96 in April. Considering that the peak value of GSI and the high percentage of V maturity stage of R. caspicus is observed in March and April; it can be prohibited to catch this species in this time.

Mitochondrial genome is an ideal model to study evolution and phylogenetic relationships. In this study, complete mitochondrial genomes of six species of Caspian sea sturgeon including Persian sturgeon, Russian sturgeon, Ship sturgeon, Sterlet sturgeon, Starry sturgeon and Beluga sturgeon along with separate nucleotide and amino acid sequences of 13 PCGs per each genome including ND1, ND2, ND3, ND4, ND5, ND6, ATP6, ATP8, COX1, COX2, COX3, ND4L and CYTB were retrieved from NCBI database and compared. The results obtained from sequence distance analysis by DNAStar software based on complete mitochondrion genome showed high genetic similarity (99 %) between Persian and Russian sturgeon. Also, the lowest similarity (95 %) was observed between Sterlet and Starry sturgeon. In phylogenetic analysis by MEGA7 software, two main clusters with two sub-clusters for one of the main clusters were identified. Persian and Russian sturgeon species were grouped in first sub-cluster, Ship and Sterlet species fall in the other sub-cluster and Starry sturgeon with Beluga formed a different distinct cluster. The results obtained from the comparison of the 13 PCGs sequences were similar to the sequences of the complete mitochondrial genomes. The most difference in nucleotide sequences were observed in CYTB, ATP6, ND2, ND5 and ND6 genes and the lowest difference for ND4L gene. The results obtained from the comparison of the 13 genes amino acid sequences were different as the order of the species was changed and 100 % genetic similarity were observed for some genes such as COX3 and ND4L genes. Based on the results of the present study, mitochondrial genome sequences could be used for phylogenetic analysis and clustering of different species of sturgeons. However, the accuracy of investigations by complete mitochondrial genomes is higher than the nucleotide sequences of the genes, and using the amino acid sequences is not suggested due to their codon nature.

  A total of 1,200 A. stellatus juveniles at different ages of 55, 69, 77 and 85 days were stored at a density of 100 eggs per square meter. Habitation of A. stellatus juveniles in four breeding treatments including 55 days (0.5-1 g), 69 days (1-3 g), 77 days, (3-5 g) and 85 days (5-10 g) in water Accepted and 4 experiments in different salinities (0-- 0-5, 4-5 /., 9-4 and 9-13) and each experiment was designed in 4 treatments and each treatment had 3 replications. The results of the present study showed that the best breeding period for releasing juvenile A. stellatus fish into the sea (salinity 9-13) during 77 and 85 days (3 to 5 and 5 to 10 g) (df = 3, F = 8.933 P = 0.006) and (, df = 3, F = 68.800 P = 0.000). Is, which has the lowest loss rate.

The aim of this study was to evaluate the environmental effects of growing rainbow trout Oncorhynchus mykiss (Walbaum, 1792) culture in cages. Data analysis was performed using information related to the storage of rainbow trout in floating cages located in the southern part of the Caspian Sea. The results showed that according to estimating the amount of nitrogen and phosphorus output of the studied cages and their concentration at a depth of 25 meters sea level, the maximum fish farming capacity in the cage is about 100 tons of biomass produced. In the study of the average effects by the Iranian Leopold method, breeding 100 tons of rainbow trout in sea cages has negligible and weak destructive effects. The results of this study confirm the maximum production capacity of about 100 tons in each breeding complex in the southern part of the Caspian Sea by maintaining a distance of at least 500 meters from other complexes.