tooraj valinassab

Global concern over the overfishing of elasmobranches is well known, with an increasing number of studies in various regions of the world. The Gulf of Oman, like other ecosystems, the increasing fishing fleet and fisheries are considered important factors affecting aquatic resources. This study aimed to assess CPUA and biomass of batoidfishes and also biomass variation in the Gulf of Oman during two last decades. Sampling was carried from October to January using research bottom trawler of “FERDOWS1”, into 8 strata from Bandar Abbas (strata J) to marine border of Pakistan (strata Q). Overall, 1743 samples of batoidfishes belonging to 15 species and 10 families were recorded. The results appeared minimum and maximum CPUA in strata L and P with 1651.5 and 34.7 kg, respectively. Also, minimum and maximum biomass were found in strata L (1341.7 tonnes) and N (16.1 tonnes). Examining the trend of changes in CPUA and biomass from 2004 to 2017 showed that, with the exception of strata L, there were decreasing trend in all other strata. The results of the present study make it clear that after the apex predators, the meso-predators are also under threat, and the future of the Gulf of Oman ecosystem and the stability of the food web require proper management for the sustainable preservation of resources of the food web.

Three research cruises were carried out using Ferdous 1 research vessel equipped with a bottom trawl net in the waters of Khuzestan province during 2018-2021 (except for 2020) to monitor the aquatic demersal resources of the northwestern waters of the Persian Gulf. During this three years’ survey, a total of 51 stations were randomly selected for sampling at 10-50 m depths for further Biomass and Catch Per Unit of Area (CPUA) estimation by Swept Area Method. Four important and commercial species including silver pomfret (Pampus argenteus), tiger-tooth croaker (Otolithes ruber), Sobaity seabream (Sparidentex hasta) and orange-spotted grouper (Epinephelus coioides) were selected. The estimated biomass for years 2018, 2019 and 2020 were 1.1,0.0 and 7.1 tons for silver pomfret; 46.8, 23.3 and 57.6 tons for tiger-tooth croaker; 59.8, 76.7 and 137.3 tons for sobaity seabream and 30.3, 3.1 and 0.0 tons for orange-spotted grouper, respectively. During this period, silver pomfret with 0.01% (in 2018), Sobaity seabream with 3.37% (in 2021) had the minimum and maximum ratio of total biomass, respectively. From point of fisheries management, the following recommendations are proposed:- Prevent any increase in catch per unit of effort (such as number of fishing vessels)          
- Control and supervise the fishing activities, fishing grounds and prohibit the illegal fishing

The increase in the consumption of heavy metals in the Persian Gulf is the result of oil release, coastal investments such as refineries and large industrial factories, in fishing and commercial, household industries, as well as agricultural runoff, which is the result of pesticides and pesticides. It is one of the dangers that have made the ecosystem with this threat. Considering the proof of the nutritional value of marine products in the past decades and the need to consume food sources and fatty acids needed by the body, it is necessary to study the increase in the amount of risks caused by the consumption of aquatic products. Considering the importance of treatments related to heavy metals in edible aquatics due to the possibility of the accumulation of these metals, 30 oily sardine fish samples and 30 food samples from the beaches of Bushehr were analyzed. Oily sardines and edible oysters are both for human consumption, and according to the reports of the past few years about the presence of pollutants, including heavy elements, in the waters of the Persian Gulf, it is necessary that these species are healthy for human consumption. Thoroughly tested. The main purpose of this research is to measure the accumulation of lead, cadmium and nickel in the muscles of oily sardines and oysters in the Persian Gulf and its consumption. The composition of lead, cadmium and nickel metals in oily sardine fish muscle was calculated as 0.4327, 0.0192 and 0.0006 respectively and in edible oyster mollusk as 0.7414, 0.0550 and 0.0025 micrograms per weight respectively. A comparative comparison with the standards specified by global organizations such as WHO, FDA and UKMAFF shows that all the following were within the standard. The HQ index was less than 1 for both species, which indicates that the consumption of oily sardines and edible oysters does not pose a serious risk to the health of consumers in terms of lead, cadmium and nickel levels.

The survival of aquatic life and natural habitats requires the preservation of rivers as the most important aquatic ecosystems. Climate change, dams, overfishing, and water pollution have put rivers, aquatic ecosystems, and fish which are biological indicators at risk in recent years. all around the world, various hydrological methods are used to improve the ecological environment, maintain the natural flow regime, and protect the ecological diversity of the ecosystem. In this study, hydrological and eco-hydrological methods (FDC Shifting, Arkansas, Tessman, Tennant, and ABF) were used to estimate the environmental flow of the Darreh-Rood River at the Moshiran hydrometric station in Ardabil province, based on statistical period of 30 years. The average environmental water requirement in the aquatic base flow method and the Tennant method were 1.51 and 1.63 m3/s, respectively, which are not suitable approaches due to the excluding of seasonal changes and severe monthly flow changes without modifications. The flow duration curve shifting method with an average environmental flow requirement of 3.67 m3/s was better than other methods due to the bio-management class in accordance with the conditions of the region. Furthermore, this study discovered that in the lack of complete ecological data, hydrological indicators and environmental classes in flow duration curve shifting approach could be used to estimate environmental flow requirements.

In this study, the density and species diversity of sea cucumber in the Pozm bay in the north of the Oman Sea and adjacent to the Chabahar bay of Iran in three seasons of spring, autumn and winter were studied. Sampling was done by diving method in an area of 314 square meters in Pozm bay in five stations with different substrates. The samples were identified after transfer to the laboratory with the help of valid identification keys and the species Holothuria leucospilota, H. arenicola, H. atra and Stichopus variegatus were identified and H. leucospilota was identified as the dominant species in the region. Shannon, Margalf, Simpson and Pilo indices were used to study the species diversity of sea cucumber. The results showed that the highest density was recorded in winter 94 with an average of 4.64 73 0.73 in 314 square meters and the lowest in spring with an average of 0.419. 1.8 in 314 square meters. Also Shannon (0.12 ± 0.97, 0.25 ± 1.16, 0.23 ± 1.16), Margalof (0.11 ± 1.46, 0.09 ± 1.69, 0.21 ± 1.61), Simpson (0.04 ± 0.356, 0.07 ± 0.164, 0.01 ± 0.245) and Pilo ( 0.11 ± 0.112, 0.08 ± 0.837, 0.18 ± 0.91) showed different values in winter, spring and autumn, respectively. Therefore, different species of sea cucumbers in the Pozm bay were identified with species richness and low density that if proper conservation and exploitation measures are not taken, the current stocks of sea cucumber in this ecosystem will be severely reduced.

In this study, the seasonal changes of plankton in the north of Oman Sea have been investigated using the three-dimensional Regional Ocean Modeling System (ROMS) model. The initial conditions of the model follow the preliminary conditions as in WOA5 data with a horizontal resolution of 0.25 degrees and a time step of 300 seconds for one year. Vertical coordinate data were for 30 layers sigma levels by interpolations in the vertical direction of temperature and salinity. Due to the greater sub-model compatibility, ROMS model is coupled with Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) model. The simulation results showed that: (1) Temperature change is one of the main factors in the frequency of phytoplankton and zooplankton blooms; (2) Clock and counterclockwise Eddies, which represent the phenomenon of extra down or upwells in the Sea of Oman and the Strait of Hormuz, causes the transfer of chlorophyll from the south to the north; (3) The amount of chlorophyll is higher during winter compared to summer. It can be due to the presence of seasonal thermocline layer which prevents blooming despite the availability of nutrients; (4) The phytoplankton cncenteration changes in a period of one year shows that their maximum value is in late March and early spring, and April is the peak of zooplankton due to the increase in phytoplankton population. Moreover, the density of plankton depends mainly on mineral nutrients, therefore, the availability of minerals is often considered as a key factor in their growth and metabolism; (5) Chlorophyll content shows a positive correlation with water surface temperature in winter (r = 0.965), while a negative one in summer (r = -0.549). There is a significant difference between chlorophyll density in winter and summer (p <0.05). There was a positive correlation between amount of chlorophyll and nitrate in winter (r = 0.268) and summer (r = 0.794), which suggests a significant difference between winter and summer (for p <0.05); (6) There were good agreements between satellite observations of temperature and chlorophyll and the values measured in numerical modeling in majority of the cases.

This study aimed to identify the effect of environmental conditions on the diversity and abundance of polychaetes in the southern shores of the Caspian Sea in Guilan, Iran. Sampling of seasonal sediments was done (June 2017 - May 2018) in 4 stations and three depths of 1, 5 and 10 m with the help of a Van Veen grab sampler with cross section of 225 cm2 and three replications. Temperature, salinity, pH, dissolved oxygen, suspended solids and organic matter were recorded at each station. A total of 2711 polychaetes belonging to 5 species, 5 genera from 3 families were identified. The highest abundance was related to H. kowalewskii (39%) and the lowest abundance was related to H. invalida species (3%). The mean density in the four seasons of spring, summer, fall and winter was 67.66, 81.25, 48.66, and 28.33 worms per m2, respectively. The highest species diversity was 2.16 species per square meter and the biomass of 62.75 mg/m2 in spring and the lowest was in winter. The highest density, diversity and biomass were 80.41 worms per square meter, 2.33 species per square meter and 70.83 mg/m2 on the shore of Chamkhaleh, respectively; and the lowest were 16.83 worms per square meter, 1.5 species per square meter, and 31.41 mg/m2 on the shore of Chaboksar, respectively. The highest density, diversity and biomass were 127.87 per square meter, 3.68 species per square meter and 107 mg/m2 at a depth of 10 meters, respectively. The correlation results showed that among environmental factors, only organic matter had a direct significant relationship with species diversity. Density had a significant direct relationship with temperature and organic matter. Other factors did not show a significant relationship. The results of stability level of different species in the southern shores of the Caspian Sea (Guilan province) showed that N. diversicolor and H. kowalewskii species exist temporarily and other species randomly.

The present study aimed to the biodiversity of Chondrichthyes and distribution of this group of aquatic animals in the Persian Gulf and Oman Sea using biodiversity indices and finally, the maps were ploted using the GIS software. Data collection was carried out from October to December 2018 using bottom trawler by Ferdows from Sistan and Baluchestan and Hormozgan provinces waters in the Persian Gulf and Oman Sea. A total of 4014 specimens were caught in the study area, of which 245 specimens belonged to 10 species and 4 families of sharks and 3769 specimens belonged to 21 species and 12 families. The results showed that Margalef species richness index varied from zero to 1.82 for sharks and from zero to 2.65 for batoids. Also, the Pielou’s evenness index varied from 0.43 to 1 for sharks and from 0.11 to 1 for the batoids. Also, the Shannon index varied from zero to 1.9 for sharks and zero to 1.86 for batoids. The Shannon Diversity Index distribution for sharks only showed a range of 54 to 56 degrees longitude (range south of Qeshm Island to Bandar-lengeh) as a hotspot compared to the rest of the study area. On the other hand, the distribution of this index showed two points, range from 57 to 59 degrees longitude (Sirik to Meydani) and of 53 to 55 degrees longitude (Kish Island to Qeshm Island) as hotspots for the presence of batoids.

This study investigates length–weight relationships of six clupeid species ( Alosa braschnikowi , Alosa caspia , Dussumieria acuta , Nematalosa nasus , Sardinella albella and Tenualosa ilisha ) captured from three main water bodies of Iran (Persian Gulf, Oman Sea and Caspian Sea), to evaluate if the LWR parameters fit for these fishes having specific morphological characteristics. Based on the obtained results, i) the b value was influenced by recorded length (TL, SL, FL) and body shape, ii) it was within the expected range of 2.27–3.48, iii) length–weight relationships were highly correlated and significant (r2>0.82-0.98, P <0.001), and hence length-weight equations fit well with six clupeid species in the Iranian water bodies. The results presented here, would be useful for fishery biologists and fisheries stake-holders in the study area

 Biodiversity indices and abundance of demersal resources in Hormozgan waters (53 00E to 57 00E) was studied by bottom trawl survey during winter season, 2013. Sampling was done by R/V Ferdos 1. In this study, 89 stations within the 10-20 m, 20-30 m and 30-50 m depth layers were sampled and abundance and species diversity of demersal fish communities at different depths were evaluated using various indices. In this study 99 taxa communities were identified including 88 fish species and 13 species or species groups that belonged to the other marine organisms such as crabs, sea cucumbers, sea snakes, jelly fish and corals. The value for the Shannon (H́) index for the entire investigated area (10-50 m depths) were 3.21, Simpson (D), 0.06, Pielou (J), 0.69, Margalef (R), 7.55 and Menhinick (IMen), were 0.16. The value indices in different depths of 10-20 m, 20-30 m and 30-50 m were identical. Based on the results of Shannon and Simpson indices, this area has a fair quality of population in number of species, however species richness indices indicated low species richness and due to high water temperature and salinity degree, this area is under stress.

In this study, trophic interactions were studied among three elasmobranches including Iago omanensis, Rhinobatos punctifer and Torpedo sinuspersici coexisting in the depth ranging from 50 to 100 meters in the Oman Sea (Sistan and Balochistan waters). A total of 238 specimens were collected using industrial bottom trawlers of ‘FERDOWS’ during spring and summer,2014 and their stomach contents were analyzed based on VI, FO, %IRI indices and nMDS analysis. Results showed that I. omanensis fed mainly on teleosts, and crustacean and cephalopod were found in the several stomachs. Moreover, T. sinuspersici had specialized diets on teleosts. On the other hand, R. punctifer had a specialized diet on crustacean. An analysis of similarity showed significant differences among three studied species (R=0.574; P=0.001). Analysis of pair-wise tests detected the greatest dietary differences between R. punctifer and T. sinuspersici, while I. omanensis and T. sinuspersici showed the lowest differences. The results showed that there is resource partitioning, which can be related to morphology and feeding behavior of each species.