فهرست مطالب t. valinassab

The assemblage structure of bottom associated fishes across the northern coast of the Persian Gulf has received little attention. The present study was conducted in the waters more than 10 m. of northeast coasts of the Persian Gulf. The autumn data of a bottom trawl survey targeting demersal fishes were used to describe the assemblage structures and their response to environmental variables. A total of 165 and 145 demersal fish species were sampled in 2014 and 2016, respectively. The assemblages were dominated by bony fishes, prevailed by Gilded goatfish (Upeneus doriae), followed by batoid fishes, prevailed by the Arabian banded whipray (Maculabatis randalli), and sharks, prevailed by Whitecheek shark (Carcharhinus dussumieri). The results indicated a reduction in the species richness over the two-year periods in the studied area. The highest species richness was observed at depths of 20 to 30 meters, with a downward trend to shallower and deeper waters. The BEST routine showed that temperature, EC, salinity and pH best described the distribution pattern of bottom-associated fishes in both years. Additionally, CCA analysis demonstrated three bathymetrical assemblage structures for bottom-associated fishes in the studied area. Among different environmental variables, the depth seems to be a major one distinguishing the communities.

The Persian Gulf waters, like other tropical regions, are rich in aquatic animal fauna and demersal trawling is one of the most common and practical methods to exploit aquatic resources. In the meantime, fishing vessels equipped with trawl nets can generate large amounts of bycatch and subsequent discards. This study aimed to identify fish species and estimate catch per unit area (CPUA) in the shrimp trawl bycatch off northwestern coasts of the Persian Gulf. The data were collected during trawl hauls for one year (September 2021– September 2022) between Delwar and Helle fishing grounds at three depth layers. The bycatch samples included 75 fish species with a total CPUA of 2392.4 kg/nm2. The largest amount of the discarded bycatch (77.8%) belongs to teleost and cartilaginous fishes, of which gilded goatfish and Japanese threadfin bream accounted for the first and second places with a total CPUA of 433.9 kg/nm2 and 202.8 kg/nm2, respectively. The abundance of the identified bycatch varied at different water layers, and the highest bycatch rate was obtained in the depth water (21-30 m; 44.1%) and the lowest value was recorded in the shallow water (up to 10 m; 21.7%). Fifteen fish species had percentage of occurrence (100%) at all studied depths. According to the distribution map provided by ArcGIS software, the density of discards was increased by moving toward the western part of the Persian Gulf. The assessment of the bycatch composition of traditional shrimp trawler fisheries is not only practical to take preventive actions regarding the marine ecosystem balance but also the results can be used as an ecological model to evaluate the risk of the trawlers in the study area.

The present research project has been implemented with the aim of introducing aquatic research axes based on the pillars of food security. For this purpose, the stakeholders, strengths and weaknesses, threats and opportunities of the sub-sector of fisheries and aquatics were investigated and the basic research axes were determined based on the elements of food availability, access to food, food consumption and health, and the stability and sustainability of food. Also, in addition to determining the research axes, the research priority of different groups and species of aquatic animals was determined based on the scoring index (0-10). The results showed that the beneficiaries of the fisheries sector have a wide range and the main ones who will directly benefit from the research results are aquaculture farmers, fishermen, processors and exporters of aquatic products. From the point of view of strengths, weaknesses and opportunities and threats, the existence of valuable genetic resources, fisheries knowledge and the country's policies for the development of fisheries and aquatics are among the strengths, and natural factors such as pollution of water resources, reduction of marine resources and climate change are among the most important threats. are counted From the point of view of the main axes of research in the pillar of food availability, fishing, stock assessment, aquaculture, health and aquatic diseases, in the pillar of access to food, supply markets, economic and social issues and the final price of the product, in the pillar of food consumption, quality and consumption culture, in the pillar of food sustainability, sustainable exploitation of aquatic life, reduction of waste, and increase in productivity were identified as priorities. In terms of species priority based on fertility, cold-water fish breeding, production management in shrimp, cold-water and warm-water fish, product health and transformation industries were given the highest points. In Caspian Sea aquatics, the most research points were given to health, nutritional value, storage, maintenance and market, and important Persian Gulf and Oman Sea aquatics received the most points for health and exploitation management.

Investigating the relations and mechanisms of coexistence among sympatric species is essential to comprehend their ecological roles in the food webs. In the present study, the diet and trophic interactions of 5 abundant teleost species coexisting in the northern Oman Sea were examined using stomach contents analyses. The cumulative prey curves showed that the sample size of each studied species was large enough to clarify the general dietary preferences. The vacuity indices of Netuma thalassina, Plicofollis dussumieri and Otolithes ruber were less than 50%, indicating the comparatively gluttonous behavior of these species, while the estimated vacuity indices of Lutjanus johnii and Carangoides malabaricus were more than 50%. Assessment of %IRI (index of relative importance) revealed that diets of N. thalassina, O. ruber and C. malabaricus were similar and consisted mostly of teleost fishes followed by crustaceans. Conversely, P dussumieri and L. johnii mostly fed on crustaceans followed by teleost fishes. Results showed that P. dussumieri and L. johnii occupied an intermediate trophic level, whereas N. thalassina, O. ruber and C. malabaricus occupied high trophic levels, placing them as top predators in the food web. In total, analyses indicated that there were no significant differences in diets between these 5 teleost species.

Marine benthic macrofauna plays an important role in ecosystem processes in the marine benthic zone. This study aims to investigate the biodiversity pattern and identifying benthic macroinvertebrates in the coastal zones of the Persian Gulf and the Gulf of Oman. Two sampling periods were performed in this study; the first: from November 2018 to January 2019 and the second: from December 2019 to January 2020. Sampling was carried out at 19 sites with three replicates (171 samples). A total of 164 species belonging to 85 families and 31 orders were identified. The most abundant families were Ampeliscidae and Apseudidae with mean values of 19.5±42 and 11.1±18 in m2, respectively. The most abundant class were Malacostraca and Polychaeta. The family Nephtyidae with eight identified species was the most in all stations. Amphipholis squamata, Byblis sp., Capitella capitate, and Amphioplus sp. were the significant species that contributed to the differentiation between stations. Furthermore, according to CCA analysis, dissolved oxygen (DO) showed a strong direct relationship with Callianassidae, Anthuridae, Paraonidae, Maeridae, and Corophiidae. Also, a strong indirect relationship was found between Haminoeidae and DO. Turbidity showed a strong direct relationship with Flabelligeridae and as well as weak direct with Cirratulidae. Furthermore, chlorophyll-a showed a strong direct relationship with Nereididae, and other parameters showed a medium direct relationship with Maldanidae and Haminoeidae. The Composition of bed sediment was also showed a strong relationship with macroinvertebrates communities in the study area. The diverse health status was not totally in a good condition and needs to be improved. These findings could be applied in further studies for habitat management and monitoring programs.

Reproduction biology and feeding habits of black mouth croaker, Atrobucca nibe, was investigated monthly from September 2013 to August 2014 in the Oman Sea. The specimens were collected by bottom trawl in the Northwest of Oman Sea. A total of 637 fish specimens examined, 284 males and 353 females were sexed. The average sex ratio was F: M= 1.24:1, showing dominance of females over the males. Spawning season of A. nibe was mostly observed in June and October but spawning might be occurred in all year long . The mean absolute fecundity was calculated 97008±55553 eggs, with a moderate linear relationship between absolute fecundity and total length (Fecundity= 10802TL-280712, R2=0.7624). The mean length at first sexual maturity (Lm50 %) was 35 cm for females. A. nibe is an abstemious feeder according to the high vacuity index (VI=86.5±16.8 %). Skinny cheek lanternfish (65%), Japanese threadfin bream (13%) and deep-sea shrimps (11%) were the frequent food items of this species. Results showed that  bony fishes were consumed by all size-classes, skinny cheek lanternfish (42.1%) and Japanese threadfin bream (79.4%) were more pronounced in size-class of 34-38 cm, and also  crustacean were more frequent (29%) in 22-26 cm size classes.

In the present study, a trophic structure model for some fish species of the northern Oman Sea is developed through using mass balance modeling software, Ecopath with Ecosim (EwE). In this model, we simulated 16 functional groups spread across an area of 3998.20 km2 from 2017 to 2018. Mean trophic level in the area of the present study was 3.49. Values calculated for system omnivory and connectance indices were 0.42 and 0.44, respectively. However, the values of ecotrophic efficiency in the model were high (>0.5) for most consumers of high trophic levels except for sharks and rays because of their high fishing mortality. Accordingly, mixed trophic impact showed that phytoplankton and detritus positively impacted almost all ecological groups. Also bentho-pelagics, the medium demersals, benthos, and crustaceans had a very negative impact on themselves due to cannibalism. Furthermore, the highest realized trophic level was 4.34 for sharks. The maximum omnivory index is calculated as 0.99 for medium demersals for feeding on a wide variety of preys. Also, the average catch per net primary production, i.e., the gross efficiency of the system was around 0.000198 (lower than the global average) indicating that the fishery is harvesting fishes high in the food chain. The primary production/respiration (PP/R) ratio is found to be 3.57 and the values of ascendancy (45.40%) and overhead (54.60%) showed stability of the ecosystem. Thus northern Oman Sea can be classified as an immature ecosystem (in the developmental stage), although it has some kind of system maturity. Accordingly, the food web of northern Oman Sea is consisted mostly of detritivorous, planktivorous, and carnivorous fish species. Besides, Ecopath with Ecosim (EwE) software can be an excellent option to examine interactions among ecological groups, and the impact of fishing in northern Oman Sea which is unquestionably helpful to develop concrete management strategies. The proper ecosystem-based fisheries management practice can improve the efficiency of this overexploited ecosystem.

The genus Sargassum C. Agardh (Sargassaceae, Fucales), despite considerable research efforts, is still one of the most systematically complex and problematic genera of Phaeophyta. The marine algal flora of Iran received little attention than other marine water bodies. This paper describe 7 species as Sargassum new records along the Iranian coasts including Sargassum baccularia (Mertens) C. A. Agardh, S. binderi Sonder, S. gemmiphorum Tseng et Lu, S. longifructum Tseng et Lu, S. henslowianum C. Agardh, S. boveanum J. Agardh var. aterrimum Grunow and S. spinuligerum Sonder. The more consistent morphological characters for each species were recognized and these characters include: Holdfast shape, length/width leaves, leaves margin and apex, vesicles and receptacles shape.The most common species were S. spinuligerum, S. baccularia, S. henslowianum and S. longifructum distributed widely in Sistan va Baluchestan province and S. binderi, S. boveanum var atterimum restricted to Bandar Langeh and Bushehr province, respectively.

Morphometric comparison of sagitta otolith in 10 clupeid species of the Persian Gulf and Oman Sea including Anodontostoma chacunda, Dussumieria acuta, Dussumieria elopsoides, Ilisha megaloptera, Ilisha melastoma, Nematolosa nasus, Sardinella gibbosa, Sardinella longiceps, Sardinella sindensis and Tenualosa ilisha), was conducted during 2007-2008. We found no significant differences in morphology and morphometry of the left and right otoliths except for A. chacunda and N. nasus. For the latter species the left sagitta otoliths were used. Investigation of otolith morphometric characteristics (length, breadth, weight, perimeter, area, and number of scallops) was also conducted which showed perimeter and number of scallops were the most effective individual otolith characteristics for distinguishing between species. The study indicated that sagitta otoliths have particular morphometric characteristics which are useful in identification of these species.

The feeding habit of Pennahia anea was studied in the north-west of Oman Sea by collecting 188 specimens during years 2010-2011. The samples were collected seasonally with midwater trawls during lantern fish fishing. Vacuity Index (VI), Fullness Index (FI), Gastro-Somatic Index (GaSI) and frequency percentage of different food items were also studied. Of total stomachs, 40 stomachs were full or semi-full and the other 148 were empty. GaSI Index average was 1.1 for the total year. The mean Vacuity Index was calculated 78.7% and amount of Food Preference Index were estimated as: Fishes (92.5%), Crustacean (22.5%) and Molluscs (5.0%). b= 3.12 shows isometric growth in the P. anea. It was concluded that P. anea is a relatively abstemious species and its main food was Fishes and minor foods was Crustacean.