فهرست مطالب ali haghi vayghan

The effects of storage of rainbow trout processing by-products at 4 ºC on fatty acid composition and nutritional values of hydrolyzed-derived oils were determined. Polyunsaturated fatty acids (PUFA, 39.97-43.70%) were the major fatty acids followed by monounsaturated (MUFA, 31.90-34.05%) and saturated (SFA, 19.27-22.59%) fatty acids. Among fatty acids, linoleic, cis vaccinic, and palmitic were the main fatty acids. N-6 fatty acids represented 34-38% while n-3 fatty acids were 4.5-6.6% of all fatty acids (P<0.05). Hypocholesterolemic/hypercholesterolemic ratio (h/H) index in oils was between 4.23 and 5.15. The highest value was found at day 2 while showed no changes among other storage times (P>0.05). Thrombogenic index (TI) at days 0 and 2 were the lowest among storage times while at days 5 it represented the highest value. However, the change was not significant (P>0.05). N-6/n-3 ratio ranged from 5.01 to 7.6. PUFA/SFA was between 1.77 and 2.29 and showed the highest value at day 2 while after 5 days significantly decreased (P<0.05). The highest fish lipid quality (FLQ) index was for fresh by-products (day 0) (P<0.05) and showed no differences from day 1 to 5 (P>0.05). Also, nutritive value index (NVI) ranged from 2.25 to 2.55 with no significant differences during storage (P>0.05). The sum of EPA and DHA was between 1.73 and 4.05% and decreased with increasing storage days (P<0.05). Polyene index (PI) decreased to the end of storage time up to 4 days compared with the fresh by-products and significantly decreased thereafter after 5 days (P<0.05). Results of the present study showed that fatty acid composition and nutritional quality of oils from hydrolysis-derived oils were influenced by the storage days to some degree.

Hilsa shad (Tenualosa ilisha Hamilton, 1822) is a migratory fish and as one of the most important species in the southern parts of Iran, so that during the last decade, the amount of its catch has fluctuated a lot. Due to the limited data available on the stock of this species in southern waters, it is not possible to use models based on complementary data to assess its stock. In the present study, to determine the stock status of Hilsa shad in southern waters, the catch-maximum sustainable yield (CMSY) model was used. Catch data from1997 to 2019 were collected and entered into the model to calculate fisheries reference points. The value for B/BMSY by the model was estimated to be less than 1.0 and the value of F/FMSY was more than 1.0, which indicates the critical situation of this species in the southern waters of Iran and that the stock is under fishing pressure. Based on the obtained fisheries reference points, the MSY was estimated as 4,360 Mt which due to high fishing pressure and depletion of stock that has occurred during these years, in the years after 2012, has never reached to this amount of catch and, the amount of catch has been less than the MSY. Considering that more than 92 percent of the catch of this species is done in the waters of Khuzestan province, so the management strategies for applying restrictions in the fishing effort and fishing licenses for traditional fishing vessels should be mainly concentrated in this area and it is recommended to stop fishing of this species so that the stock could find the opportunity to rebuild.

Aras dam has ecological and socio-economic importance in the West Azerbaijan province, which freshwater crayfish (Astacus leptodactylus) is one of the pristine and important sources of export. To investigate the stock status of this species, two models CMSY and BSM were used from 2013 to 2018 and catch data were analyzed in this respect. Sampling was performed in July 2021 in Aras Dam reservoir. The average catch weight was 88.91 g, total and carapace length was 13.88 cm and 7.5 cm, respectively. The amount of CPUE (Number per trap per day) calculated per day in Station I and SII were 0.06 and 0.013, respectively. Fisheries reference points obtained from CMSY and BSM models showed that the maximum sustainable yield of Aras Dam crayfish was between 18 and 24 t. These results indicated a sharp decline in stock and fishing over the sustainable yield, during the past years. Therefore, it can be generally concluded that the freshwater crayfish stocks of Aras Dam severely damaged. Considering the population parameters, and stock status, as well as the reasons of stock depletion, it can be hoped that if the stock rebuilding program and also the exploitation is defined based on sustainable harvest and maximum allowable catch planned gathered from the results of this study. Therefore, rebuilding of the stocks of this species and prevent its extinction are possible..

Scomberomorus guttatus (Bloch and Schneider, 1801) is one of the most important commercial fish of the Scombridae in the southern waters of Iran, which plays an important role in the human diet. The catch of this species has increased in recent years, and due to the limited data available on its stock in southern waters, it is not possible to use models based on complementary data to assess its stock. In the present study, the catch-maximum sustainable yield (CMSY) and the Bayesian surplus production (BSM) models were used to determine the sustainable exploitation and fisheries reference points of Scomberomorus guttatus caught in the southern waters. Data related to the last 23 years from 1997 to 2019 were collected and entered into the model to calculate fisheries reference points. According to the results, it seems that the BSM model applies the estimates with less sensitivity. The calculated value for B/BMSY by the CMSY model was estimated to be more than 1.0 and the value of F/FMSY was less than 1.0, which indicates the healthy stock status of this species in the southern waters of Iran. By applying the forecasting model, the increasing trend of fishing was predicted in 2033. If this trend continues, the value of B/BMSY will fall below 1.0 and the value of F/FMSY will increase to about 1.99. If the catch is not reduced from 2028, the stock will start to decrease in the years after 2030 and will be overfished. Based on the obtained fisheries reference points, the maximum sustainable yield (MSY) was estimated as 9,000 tons, and this amount was predicted to be 15,000 tons in 2033. In general, the estimated fisheries reference points in this study can be an effective aid in understanding the status of Scomberomorus guttatus stock in the southern waters of Iran and reveal the effects of the application of management policies on its stocks, which can ultimately develop compatible management plans for proper exploitation of its stocks in the region.

Golden barb, Carasobarbus luteus (Heckel, 1843), belongs to the Barbus genus and is one of the freshwater species of Iran and native to Shadegan wetland. Some biological characteristics of Carasobarbus luteus were studied in Shadegan Wetland. Monthly samples were collected from five stations; Doragh (Mahshahr), Rogabe, Khorosy, Salmane and Atish from April 2013 to Mars 2014. 1608 specimens (276 males and 1332 females) were collected and measured. Results showed Mean±s.d length values for the male and female were calculated as 161±28(110-222), 174±38(95-280) mm respectively and mean±s.d weight values were 60±31(15-175), 80±39(15-370)g respectively. The length-weight relation were calculated as W=0.00003L2.83 (R2=0.84) for males, and W=0.0001L2.80 (R2= 0.86) for female; that determined negative allometeric model. The mean values of condition factor (K) were 1.77± 0.14 in males and 0.78± 0.27 for females and have no significant different (P>0.05). The spawning peak was determined in April, and length at maturity (LM), consume per biomass (Q/B) and production per biomass (P/B) were calculated for males and females as below LM=152, 139 mm; P/B= 0.71, 0.52 and Q/B=15.41, 12.37 respectively.

Phytoplankton is one of the main components of wetlands, which plays a vital role in providing nutrients, oxygen for other organisms, stabilizing nitrogen and carbon dioxide. In the meantime, the current status of Lake Urmia highlights the need to conserve and protect wetlands related to these ecosystems and their living and non-living components. Therefore, this study was conducted to assist in the restoration of Lake Urmia by monitoring the hydrobiological status of Solduz wetland. Field surveys and sampling of Solduz Wetland were carried out from 6 stations in summer and winter of 2016. Sampling was performed using a vertical rotor with a diameter of 10 cm. The effects of physicochemical factors and temporal variations on the diversity, abundance and biological characteristics of phytoplankton in the ecosystem were investigated. In total, 49 phytoplankton species were identified from the Solduz wetland: 17 species belonging to green algae, 16 species belonging to diatoms and 9 species belonging to cyanobacteria and some others species. The results of this study showed the presence/absence of the mentioned algae may be caused by changes in the physicochemical especially temperature, nitrate, phosphate, pH and electrical conductivity which occur naturally in different seasons. So that the population density index and biodiversity indices such as species richness, species diversity and dominance was observed in the warm season more than the cold season. The results of this study can assist executive managers in Urmia Lake monitoring plans for better management and utilization of related wetlands of Lake Urmia.

To achieve comprehensive management of marine resource stocks requires knowledge of the variables that affect economic species. Longtail tuna (Thunnus tonggol) is one of the most economic species in the southern waters of Iran. Recent study tried to find out the association between the most important satellites derived environmental variables with longtail tuna catch and distribution by applying Generalized Additive Model (GAM) in the southern waters of Iran. Results indicated the relatively high importance of temporal (month of fishing), spatial (latitude), and three environmental variables as Sea surface salinity (SSS), mixed layer depth (MLD), and Sea surface temperature (SST). Deviance explanation of the GAM model defined as 62.3% and adjusted R-square was 0.595. Maximum Entropy (MaxEnt) habitat suitability modeling by selected tree environmental variables shows longtail tuna inhabited mostly in latitude between 24°N and 26°N close to Hormozgan and Sistan and Balochistan province waters. The current study by detecting most important satellite derived environmental variables and high suitable habitat, could assist decision makers and fishery managers to improve fishing efficiency of Iranian purse seiners and helps implementation of ecosystem-based fisheries management of shared stocks in southern waters of Iranian.

Association between environmental variables and target species is the most important point in aquatic ecology. This study considered the possible relationship of spatial, temporal and some satellite derived environmental variables on skipjack tuna (Katsuwonus pelamis) distribution to finally help implementing of ecosystem based fisheries management for stock recovery program and management of skipjack tuna. Results of generalized additive model (GAM) (by assuming two distributions; binomial and Gaussian) revealed temporal and spatial explanatory variables plus net primary production (NPP), sea surface temperature (SST), sea surface salinity (SSS), mixed layer depth (MLD) and ocean current indices have greatest impact on skipjack tuna distribution in both cold and warm season. Comparing of two different model showed, binomial distribution had higher ability in final model deviance explanation and its value in warm season was higher than cold season. In addition, habitat suitability study showed suitability of some parameters in cold and warm season were different, then it must be noticed in future studies. Since the first step in implementing ecosystem based fisheries management is the sufficient knowledge on ecosystem and distribution of target species in relationship to environmental variables, therefore this study could help Iranian purse seiners to improve their catch efficiency in order to help to implementing of ecosystem based management for skipjack tuna and future fisheries management in the Indian Ocean and Oman Sea.