مهسا حقی

The purpose of this study was to examine the secondary production of the dominant species of the Acartiidae family in the Arvandrud estuary. Specimens were sampled monthly for one year, at eight stations from December 2018 to November 2019. Sampling was conducted with a 300 µm mesh size plankton net and a 45-cm-diameter mouth. Environmental parameters such as temperature, salinity, dissolved oxygen, depth, and water turbidity were measured monthly. Five species belonging to the Acartiidae family were identified, including Acartia pcifica, A. fossae, A. danae, A. faoenis, and A. ambionesis. Due to the highest percentage of frequency for A. pacifica (107± 40 ind.m-3), and because of its presence in most months and stations, it was known as a dominant species. The measurement of the total length of A. pacifica showed that the length of this species along the Arvandrud River has relatively similar values. The average length measured in station 2 has the highest value (0.122±0.016) of the total length. Biomass changes in this species showed the highest amount of biomass in spring (1.24 mg of carbon per cubic meter) and the lowest amount in autumn (0.46 grams of carbon per cubic meter). Secondary production of dominant species was obtained at 0.99 mg C.day-1 during the summer and at 0.25 mg C.day-1 in the autumn. According to the Pearson correlation, there was no significant correlation between identified species abundance and larval abundance at different stations.

This study was designed to determine the effect of rainbow trout culture in floating cage on the distribution and structure of Phytoplankton community in the Abbas Abad area, southern basin of the Caspian Sea. For this purpose, water and phytoplankton samples were collected by a distances of 5, 50, 100 and 1000 m from the cage culture during December 2014 (pre cage), March and April (production period) and August 2015 (post cage). The results of physicochemical factors of water showed that most of the measured parameters had significant differences only among different sampling periods (P<0.05). In this study, 42 taxa of phytoplankton belonging to five phyla (with the dominance of Bacillariophyta) were identified. The results showed that the abundance of most dominant phytoplankton samples had a significant difference during different periods (P<0.05), but this significant difference between different stations was observed for few species studied only. Also, the results of determining the effect of environmental factors using CCA test on the Bacillariophyta abundance showed a minor impact and a positive correlation with turbidity and total nitrogen, While the effect of temperature and ammonium on its abundance was negative. It seems that the rainbow trout cage culture in the Abbas Abad region had a minor impact on water quality factors and nutrients concentration probably due to short duration of cage culture activity and high velocity currents, but no remarkable effect on phytoplankton structure in the vicinity of fish cages, so that the observed changes were more associated with seasonal fluctuant.

This study was conducted to investigate the presence and passage of marine upstream fish in the up-water of Karun River in order to investigate the necessity of constructing a fish passage in the Mard dam structure. In Bahmanshir and Arvandrud Rivers the only and most important marine migratory fish that needs to migrate and presence at up-waters for reproduction and offspring survival is T. ilisha. River fish sampling was done using gill net and local fisher man. Among different reported fish, from physiological point of view, only T. ilisha needs to presence along the Bahmanshir, Arvandrud and Karun rivers from the estuary to upstream. Given the high impact of T. ilisha on livelihoods and the preservation of nutritional health of a large number of local and indigenous inhabitants of these rivers, the conservation of these fish stocks as well as the maintenance of river structures to support its reproductive migration from ecological, social and economic perspective of the region is very important. Thus, the authors consider the construction of a fish way as essential for the dam and shipping lock of the Mared structure. Based on the design prepared for the dam and Shipping Lock of the Mard structure, it appears that the dam structure itself have some parts that can be used as fish paths. Under normal conditions of water regime, during the year, side valves in the shipping lock with open water sea level could provide enough volume and velocity of water to stimulate swimming in T. ilisha as fishing path in Mared dam structure.

This study investigated the age, population dynamics and some biological characteristics of Saurida tumbil inhabiting Hormozgan province from Kolahi to Dargahan. This study was based on the data obtained from commercial catches of shrimp trawl vessels in fishing seasons of 2019. The results of this study showed that the highest correlation was related to total length and fork length relationship with estimated coefficient of correlation (r2= 0.9988). Also the results showed a significantly correlated length-weight relationship with estimated coefficient of correlation (r= 0.9373). The value of the slope (b) was significantly different from 3 which shows a negative allometric growth for this species. The estimated age (based on vertebrae age reading method) variability were 1 to 7 years. The fish with age 2 showed the highest frequency among the age groups. Also the Bertalanffy growth equation for this species in the study area was estimated as Lt=50.02 (l-exp(-0.28 (t+0.27)). The mortality coefficients were 2.66, 0.67 and 1.99 for the total mortality "Z", natural mortality "M" and fishing mortality "F", respectively. Also, the estimated exploitation rate for this species was 0.75 which shows that this species is in overexploitation phase. Hence, to improve the present stock status in this area and sustainable capture of S. tumbil, it is recommended to decrease fishing effort and improve bottom trawl for reducing bycatch issues.

Large-head hairtail, Trichiurus lepturus, is one of the commercial fish at the Persian Gulf and Oman Sea waters, which is exploited to export outside markets. To present population dynamics and characteristics of this species, the fish caught by trawling method were analyzed from Kolahi to Dargahan areas in Hormozgan province waters. The von Bertalanffy growth equation (VBGF) was fitted to length-frequency data (n =771) to obtain a VBGF with the following parameters: L∞, K, and t0 were 88.83 cm, 0.10, and -0.07, respectively. The estimated value of total mortality (Z) and natural mortality (M) were 0.44 and 0.28 (year-1), respectively. Also, fishing mortality (F) was recorded as 0.16 year-1. Exploitation rate, corresponding to the maximum relative yield per recruit (E) was 0.36, and this fish in the present study caught capacity. Recruitment pattern showing maximum added yang fishes in September. The present results have to be considered with caution for fisheries management purposes as fishing effort is still in increasing phase. Long-term monitoring is required. To better understand the T. lepturus population dynamic and its fishery framework in the study region.

This study was carried out to determine the effect of raibow trout cage culture on the abiotic factors of water in the Abbas Abad area, southern basin of the Caspian Sea. For this purpose, water samples were collected at distances of 5, 50, 100 and 1000 m from the cage culture during December 2014 to August 2015. Based on the results, it was shown that the mean value of water temperature for surface layer varied between 12.2 and 30.16 °C from December to August. The highest and lowest mean value of salinity obtained in August (11.26 g/l) and April (10.66 g/l) respectively. The range of pH value changes (8.36-8.83) was as small as the rate of electro conductivity variations (18.11-19.07 µs/cm). The highest concentration of dissolved oxygen was observed in December at 1000 m station (9.23 mg/l) and the lowest was seen in April at 5 m station (7.27 mg/l). Also the mean values of Total Dissolved Solids, Turbidity, Nitrite, Nitrate, ammonium, Total Nitrogen, Phosphate and Total Phosphorus was obtained 9.59 (g/l), 5.55 (NTU), 3.67, 133.45, 92.6, 929.72, 21.63, 37.73 (µg/l) respectively. The results of abiotic factors of water showed that most of the measured parameters had significant differences only among different sampling periods (p<0.05) whilst, for some factors such as dissolved oxygen, ion ammonium and phosphate, there were significant differences between different stations (The effect of distance from the cage) at each sampling period as well as (p<0.05). It seems that the cage culture of rainbow trout in the Abbas Abad area had only a minor impact on measured factors probably due to low stocking density, short-term of fish farm and high current velocity.

This study was designed to determine the probable effect of rainbow trout cage culture on the biodiversity indicators in the Abbas Abad area, southern basin of the Caspian Sea. For this purpose, biological samples (benthic macro invertebrates, phytoplankton and zooplankton) were collected at distance of 5, 50, 100 and 1000 m from the cages in December 2014 (before the culture period), March and April (production period) and August 2015 (after the culture period). In this study, 9 taxa of benthic macro invertebrates (with the dominance of polychaetes; Streblospio gynobranchiata and Hypaniola kowalewskii) and 42 species of phytoplankton belonging to five phyla (with the dominance of Bacillariophyta) were identified. A total of 10 taxa of zooplanktons were identified with the copepod; Acartia tonsa being the dominant taxa as well. The results showed that the distribution and abundance of biological community were significantly affected by the seasons (p < 0.05) where as it was not affected by the distance from the cages (P>0.05) and in most cases, changes of biodiversity indicators were not affected by cage culture activity. It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on the biodiversity indicators in the vicinity of small scale fish cages due to short duration of cage culture and strong water currents, so that observed changes were more associated with seasonal fluctuant.

In order to investigate the sedimentary texture, diversity and density of benthic molluscs, 55 stations at 9 transect were collected in the Nayband Bay.Samples were taken with a Van Veen grab (0.022 m2) in 3 replications in each site.Using a Particle Size Analyzer instrument revealed that the sediment texture was dominated by sand with 7 sub distinct sub sediment. Semelidae,Veneridae and Tellinidae families belonged to bivalves were dominant families in all identifeid molluscs. In this region,sediment particle size and depth variations had significant effects on species distribution, richness and eveness.The diversity, species richness and abundance of Mollusc increased with depth Increasing.The mean value of Margalef and Shannon index interpreted the study area as contaminated region while the Pielu index described the environment without stress.

This study was designed to determine the effect of rainbow trout cage culture on the chlorophyll-a content and trophic index value in the Abbas Abad area, southern Caspian Sea. For this purpose, water samples were collected by a distances of 5, 50, 100 and 1000 m from the cages during December 2014 (before rearing period), March and April (during rearing) and August 2015 (post rearing period). In this study, a totalof 42 species of phytoplankton belonging to five phyla (with the dominance of Bacillariophyta) were identified. Chlorophyll-a content varied significantly in different periods and stations (P<0.05). The highest and lowest chlorophyll-a content was recorded in March and station 5 m (2.13 μg/l) and May and station 1000 m (0.44 μg / l) away from cages, respectively. The Trophy State Index (TSI) was significantly different between the sampling periods (P<0.05). The highest TSI (42.18) was observed in March and then in August (40.47) and this differences were significant between different periods (P<0.05), whereas, it was not affected by the distance from the cages (P<0.05). It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on Chlorophyll-a and trophic index in the vicinity of fish cages due to the small scale and short duration of cage culture activity and strong water currents, so that observed changes were more associated with seasonal fluctuant.

Blue swimming crab is one of the most important crustacean and known as a commercial species in subtropical areas. This study investigated the reproductive biology of blue swimming crab, Portunus pelagicus. Sampling was run monthly through trawl catches in the Khuzestan coast, most of the specimens were catch at the Bousif fishing site, from April to March 2017. A total of 567 crabs were collected of which 221 were males and 346 females, with a male: female ratio of 0.6:1. The carapace width and weight ranged from 60.9-164mm and 15.2-387.7g in males and 67.5-174mm and 18.3-434.1g in females, respectively. The mean carapace width was 119.37±1.59mm and 130.15±1.32mm and mean weight were 135.58±5.92g and 156.54±4.49g in male and female crabs, respectively. Body weight was significantly higher in female crabs (about 15%) (P<0.05). Gonadosomatic index was the highest in March. Also, the number of ovigerous females was the highest during May-June. The results of correlation between egg mass and total body weight showed that egg weight was more related to carapace width than body weight. Totally, it seems that the blue swimming crab has optimum reproductive environmental condition in Khuzestan coasts and could reproduce several times a year on these coastal waters. Therefore, it is possible to be a potential for export economy.

This study was designed to determine the sediment structure, Total Organic Matter (TOM) and facultative anaerobic bacteria communities of sediment affected by cage culture of rainbow trout in the coastal waters of Abbas Abad area (southern basin of the Caspian Sea). For this purpose, sediment samples were collected at distance of 5, 50, 100 and 1000 m from the cages in December 2014 (before the culture period), March and April (production period) and August 2015 (after the culture period). Determination of sediment grading showed that its structure was composed of silt-clay (91.7%) and very fine sand (6.44%) and the sediment structure was not affected by the cage culture. The Total Organic Matter was significantly different only between the sampling periods (P<0.05) so that the highest amount of Total Organic Matter (TOM) was observed during the production period whereas, it was not affected by the distance from the cages (P<0.05). It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on the factors studied in the vicinity of small scale fish cages due to the short duration of cage culture and strong water currents, so that observed changes were more associated with seasonal fluctuant.

Feeding strategy of blue swimming crab (Portunus pelagicus) was investigated monthly in Khuzestan province water from April-2016 to march-2017. Samples were catch by trawl net. The content of P. pelagicus stomachs, percentage of occurrence frequency and Frequency percentage of feeding items was checked. In crab stomachs different feeding items group such as crustacean, mollusks, sponges, phytoplanktons, corals, fish, sand particles and etc. Was observed. The highest frequency of occurrence belonging to sponges, crustaceans and mollusks, respectively. Furthermore, Frequency percentage of sponges (38.65%) was higher than other preys. Costello's graphical model analysis Results analysis of P. pelagicus stomach content by Costello's model showed that this crab is a predator with specific feeding nich and feeding specific prey include sponges, crustacean and mollusks during a year. Though, it's feeding pattern show few seasonally fluctuations. In this model, phytoplanktons, fish, polycheats, corals, nematode, protista, ctenophore, nematodes, cestod, sea insects and sand identified as accidental or rare prey. Probably, ingest by crab while feeding from specific prey.

This study was conducted to investigate the feeding habits of Copeotatrutta in Sezar River from Tigris basin (Lorestan Province). Sampling was performed monthly from July to December 2011 using seine net with different mesh size and gill net with 50 mm mesh size. For diet analysis, a total of 79 C. trutta was sampled and studied. The mean RLG index was 9.97±0.24 showing herbivores feeding in C. trutta. The mean condition factor (K), index of fullness (IF) and vacuity index (CV) were 1.44± 0.01, 1.41± 0.01, 478.08±25.26 and 1.26, respectively. All feeding items were priphyton unicellular algae. In identified feeding items, the genera Navicula, Cymbella, Diatoma and Nitzschia were identified as the main food, the genera Fragillaria, Microspora, Pinnularia, Gomphonema, Oscillatoria, Pediastrum, Rhoicosphenia, Acnanthidium, Tribonema, Melosira, Surirella, Achnanthes, Lyngbya, Scenedesmus as the supplementary food and the genera Ulothrix, Gyrosigma, Spirogyra and Closterium as the incidental food of C. trutta. The main, supplementary and incidental foods were identified. Dietary indices showed good feeding condition of this species in Sezar River.

This study was designed to determine the effect of rainbow trout cage culture on the distribution and structure of zooplankton community in the Abbas Abad area, southern basin of the Caspian Sea. For this purpose, water samples, sediment and zooplankton fauna were collected by a distances of 5, 50, 100 and 1000 m from the cage culture during December 2014 (pre cage), March and April (production period) and August 2015 (post cage). In this study, 10 taxa of zooplanktons includes 1 species belonging to the order of Copepoda, 1 species of Cirripedia, 1 species of Cladocera, 1 species of Rotifera, 1 species of Ciliata, 1 species of Foraminifera, 1 species of Aciculata, 1 Sedentaria and 2 species of larvae Lamellibranchiata and Medus were identified overally. Acartia tonsa species of copepod as dominant taxa was more abundant (%76.19) than the other taxonomic groups. The results showed that the physicochemical characteristic of water and abundance of zooplanktons had a significant differences during different periods (P<0.05), while the effect of distance from the cage was not significant (P>0.05). The results showed that environmental factors slightly affected the zooplankton abundance using CCA and there was found a negative correlation between more species of zooplankton and nitrogen compounds especially nitrates, so that the lowest abundance of zooplankton community in March with the highest total nitrogen was obtained. It seems that the rainbow trout cage culture in the Abbas Abad region had a minor impact on water quality factors and nutrients concentration due to water movements and currents, but no remarkable effect on zooplankton structure in the vicinity of fish cages, so that more zooplankton changes were associated with seasonal fluctuant.

To study Tigertooth croaker (O. ruber) diets, monthly sampling was done from March 2015 to February 2016, using commercial fisheries in the Khoozestan coasts. Totally, 307 fish were examined. The average of gastro-somatic index, condition factor, intensity of fullness and the vacuity index were calculated as 0.1±0.01, 0.99±0.04, 167.89±54.83 and 50.1, respectively. Also, frequency of occurrence index for fish and shrimp as the preys were calculated as 82.1% and 19.8%, respectively. The Relative importance index of fish and shrimp were calculated as 9.53 % and 8.62%, respectively. The intestinal contents of Tigertooth croaker (O. ruber) contained fish belonging to mugilidae and shrimp of Penaeidea family. The results of present study in Khuzestan coasts showed that this species has the optimum condition factor of fullness in spite of weak index of nutrition. It can be suggested that Tigertooth croaker (O. ruber) is a tolerant species, adapted to the environmental condition in that despite receiving low amount of food, it would gain the enough energy to manage its growth and physiologic process. It is concluded in this study that the main food of Tigertooth croaker (O. ruber) was fish and the secondary food was shrimp.

In this study, some of biological indices of crooker fish (Otholithesruber) were investigated in Khozestan coasts. Sampling was done each month, from March- 2014 to February- 2015 by near bottom trawl net with 24milimeter mesh size in commercial fishing. After fishing the samples transported to the lab and were biometry. The result of study 307 number of crooker fish showed that the total weight mean was 220.56±9.1 geram and total standard length was 23.59±0.24 centimeter. Length and weight parameter relationship was measured, too. Length and weight equation was calculated as a regression equation, y=0.0172X2.826 and R2=0.8247. In this equation, a and b Parameters were calculated as 0.0172 and 2.826, respectively. The variation of some biological indices such as intensity of feeding index, hepatosomatic index and gonadosomatic index were studied too. The results of biological indices showed that hepatosomatic index was related positively to intensity of feeding and gonadosomatic indices.

This study conducted to survey the feeding indices of small scale sardeh fish (C. damascina) in Sezar river of Lorestan Province. Montely sampling was done from Julay to December 2011 and by Purse seine net with different mesh size and gill net with 50 mm mesh size. For diet analysis، 128 number of C. damascina was used. The length and weight of sampled fishes was in renges of 18 to 33 cm and 76 to 519 g، respectively. The average of RLG index was 5. 33±0. 07 that specified the herbivory or prephyton feeder. The mean of gastro- somatic index، condition factor (K)، index of fullness (IF) and vacuity index (CV) was 0. 13± 0. 002، 1. 41± 0. 01، 340. 96±20. 77 and 5. 47، respectively. The genera Navicula، Cymbella، Diatoma and Nitzschia were identified as the main food، the genera Fragillaria، Microspora، Pinnularia، Gomphonema، Oscillatoria، Pediastrum، Rhoicosphenia، Acnanthidium، Tribonema، Melosira، Surirella، Achnanthes، Lyngbya، Scenedesmus as the supplementary food and the genera Ulothrix، Gyrosigma، Spirogyra and Closterium as the incidental food of C. damascina.

This study conducted for fish fauna identification and distributions in Sezar River, one of the main rivers in Lorestan province. The monthly sampling was done from June to December of 2011, using pursing net with 50mm mesh size. Totally, 366 fish sampled was fished. Belongs to, 7 species from2 families, Cyprinidae and Sisoridae. The identified species in this study are Capoeta damascina, Capoeta trutta, Cyprinion macrostomum, Chondrosto maregium, Barbusgrypus, Luciubarbus barbulus, Glyptothorax silviae.

This study was conducted for identifying the feeding indices of Botak fish (Cyprinion macrostomum) in the Sezar River. Monthly sampling was done from July to December 2011، using pursing net with different mesh size and gill net with 50 mm mesh size. In total 68 specimens of C. macrostomum were examined. The results of feeding indices showed that the mean of RLG was 5. 33±0. 07. Also، the mean of GI، K، IF and CV were 0. 13±0. 002، 1. 41±0. 01، 340. 96±20. 77 and 5. 47، respectively. Based on the results، Navicula، Cymbella، Diatoma and Nitzschia as main، Microspora، Coconeis، Oscillatoria، Pediastrum، Rhoicosphenia، Mougeotia، Tribonema، Synedra، Cosmarium، and Spirogyra as subsidiary and Ulothrix، Gyrosigma، Closterium Scenedesmus، Pinnularia، Gomphonema، Cymatopleura، Diploneis Oedogonium، and Melosira as an accidental food items were detected. Diet analysis showed that Cyprinion macrostomum is a priphyton feeder with a RLG of five processing an appropriate condition factor and feeding condition in the Sezar River.

Population dynamics of Ferosagittaferox (Chaetognatha) was carried out in coastal waters Of Khur-e-Mussa's Channel in Khuzestan Province, northwest Persian Gulf. Monthly samples were collected with 300 mm mesh size plankton net in oblique tow from near bottom to surface waters. In total, 7 species of Chaetognaths were identified belonging to I class (Sagittoidea), 1 order (Aphragmophora), 2 families (Sagittidae and Krohnittidae) and 4 genera (Aidanosagitta, Ferosagitta, Flaccisagitta and Krohnitta). The identified species included Aidanosagitta bedfordi, A. neglecta, Ferosagitta ferox, Flaccisagitta enflata, F. hexaptera, Krohnitta pacifica and one unknown species. Due to presence and excessive frequency of Ferosagitta ferox in all samples, we focused on its population variation as an indicator of Chaetognatha. We determined length groups for adult individuals in 4-21mm range with 1mm increments. The year round presence of juvenile and small individuals showed the continuous reproduction of F. ferox with two considerable peaks in March and July. The evaluated recruitment indicated that the species has a low growth rate and a long life cycle.