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Este artigo pretende apresentar reflexões acerca da experiência vivenciada na disciplina “Matemática e Cultura: Etnomatemática” ministrada no ano de 2017, no curso de Matemática em uma universidade pública brasileira. O principal objetivo deste estudo foi o de verificar a relevância da discussão/reflexão acerca da pesquisa etnográfica na formação inicial em Matemática e sobre os modos de ver e conceber elementos culturais em contextos distintos. Nesse sentido, será apresentada uma pesquisa desenvolvida por um licenciando ao longo da disciplina, considerando saberes e fazeres (“ticas” de “matema”) vinculados às práticas de um pedreiro na cidade de Ituiutaba/MG. Por um lado, a pesquisa evidenciou que, na maioria dos processos na construção de uma obra, necessita-se de cálculos matemáticos, envolvendo raciocínio geométrico e cálculo mental. Por outro lado, que se torna necessário envolver a discussão da matemática e cultura, evidenciando a pesquisa etnográfica na formação inicial do professor de matemática, potencializando a dimensão educacional do Programa Etnomatemática.

Region South East of the Caspian Sea (area Goharbaran) having valuable resources biological flora and fauna, the diversity of commercial fishes, especially reserves the exclusive sturgeon as well as reserves abiotic such as oil and gas resources and transit of goods through Bandar Amirabad to Central Asia , the ecological conditions for the implementation of the project is very necessary. The aim of this study was to determine species composition, spatial and temporal distribution of plankton and fish of this region. Plankton sampled from different depths (5, 10 and 15 m) were carried out. Sampling of phytoplankton did by Ruttner and sampling of zooplankton did by net with mesh size 100 microns. The fish were sampled monthly from December 2013 to July 2014 and within months was carried out. From livestock gill Monofilament.. In this study, a total of 130 species of phytoplankton of 7 filums Bacillariophyta (60 species), Pyrrophyta (23 species), Cyanophyta (22 species), Chlorophyta (14 species), Euglnophyta (9 species), Haptophyta (1 species) and Chrysophyta (1 species )and 24 species of zooplankton branch of Copepoda (5 species), Rotatoria (7 species), porotozoa (3 species), Cladocera (9 species), and Meroplankton (2 species) of larvae of Cypris Balanus and bivalves Lamellibranchiate larvae and 256 fish Acipenser persicus at 5, Alosa braschnikowi 71 number, Alosa caspia 40 number, Benthophilius lipidus 1 number, Cluponella cultriventris 72 number, Cyprinus carpio 1 number, Liza saliens 15 number, Neogobius bathybius 1 number, Neogobius caspia 5 pcs, Neogobius flauviatilis 19 number, Neogobius gorlab 6 number, Rutilus kutum 14 number, Rutilus rutilus 2 pcs, vimba vimba 4 number was observed.Different ecological conditions appointment dietary needs and relationships of organisms and their adaptations to the environment, the density and distribution of different species of phytoplankton, zooplankton and fish specifies.Also the Caspian Sea due to the type of biological species and number of endemic species (42%) in addition to comb jelly invasion, were force of the effects some species like Gloeotrichia Echinulata and as a result, now or in the future, more species will be observed and recognized will be of most interest. Also Psedonitzschia seriata ability to produce Domick acid that can be hazardous to aquatic animals and even human, was in Goharbaran area. This was considered for fishes of the southern Caspian Sea and ecological distribution of most species depends on the region. The abundance of two species of whitefish and pelagic fish in Ghahrebaran region is more than the whole Caspian Sea. On the other hand, the dominant phytoplankton of this region is Bacillariophyta and dominant zooplankton is Copepoda, which shows the goodness of these plankton branches, and by changing the various factors as the different terms of receiving solar energy and resulting in temperature and water currents can cause seasonal differences in the density of the Bacillariophyta branch and also the Copepoda, therefore one of the most important factors is season, and in the winter, when the aquatic rotation of this ecosystem increases, it increases the nutrients and moves it from the floor to the water column, and as a result, increasing the amount of silica in various levels of water can affect the nutrition of fish.

This study is attempted to compare the number of rings and circular scales that are formed during various ages on Liza saliens. Sampling was carried out monthly during 2012-2013 using beach seine fishing nets. 102 specimens of different sizes were collected and transferred to the laboratory in boxes containing ice. The age of fish was determined by the number of annual rings as well as, the number of rings in each annual area. The distance between rings in each annual area was also measured. The results showed that the maximum growth was demonstrated in the first and second years. In the first year of life, the scale radius was nearly 2823.3±366.5(µm) which decreased to 1223.9±236.0(µm). The result indicated that 48 percentage of growth scales occurred in the first year and this value is only 21.8% in the second year. The number of growth rings in the annual regions decreased with increase in age. The result demonstrated that the average number of rings was 95.5±17.6 in the first life year of the fish. If you take into account the number of growth ring through years in comparison with the number of days in a year, it is clear that one ring was nearly made in four days in the first life year and it gradually reached 7.5, 15.9, 21.9 and 31.7 in the second, fourth and sixth years of life, respectively. One ring was approximately made in each month at higher ages.

The main objectives of the present study were to estimate of biomass during 1997-2014 and maximum sustainable yield of common kilka Clupeonella cultriventris Borodin, 1904 in 2013 in Iranian waters of the Caspian Sea. This paper examines the maximum sustainable yield (MSY) and fishing intensity at MSY (fMSY) and then using fMSY, yield-per-recruit and spawning biomass-per-recruit under various harvest strategies of Fmax, F0.1 and F40%; the acceptable biological catch (ABC) was estimated. During 1997-2014, the biomass of common kilka was increased from 22000 in 1997 to 112000 t in 2009 then declined to 83300 in 2013. In the period, the instantaneous coefficient of fishing mortality varied between 0.246/yr to 1.640/yr and the exploration rates were 0.327 and 0.764. The reference points of common kilka at F0.1 and F40% were estimated 0.92 and 0.80 year−1 , respectively. According to Schafer model the MSY and fMSY were estimated 22670 t and 8690 vessel×nights (a unit of effort). During 2013, the ABC of common kilka was estimated 17500, 20060, 23500 and 18900 t in tiers 2, 3, 4 and 5, respectively. However, for the implementation of a precautionary management approach the lower and more accurate ABC-value, based on more information, should be selected and thus the catch should be restricted to 17500 t.

A mass-balance Ecopath model of coastal areas in the Caspian Sea has been constructed for a quantitative description of the trophic structure of the ecosystem. The model is used to estimate the important biological parameters and relationships among the different ecologically important groups. Twenty five species were used in the present analysis. The model is based on the data collected of Kilka fisheries, beach seining (Bony fish fisheries), and set Gillnet (Sturgeon Fisheries) and also dietary information. Total landings along the Iranian portion of southern Caspian coast reached 39647 t, including sturgeon (41 t), kilka (22873 t) and bony fishes (16733 t) in 2014. Two species of kilka (Common kilka and Anchovy) are important commercially in the Caspian Sea, together accounting in the past decade for > 60 % of the total catch, as well as being a crucial part of the food chain. The mean average trophic level was estimated at 3.17 by Ecopath software. In this research, the mean level were studied between eight species varied from 2.56 to 4.04, Sander lucioperca occupy the highest and the as vimba vimba was the lowest level. The ranges of total mortality varied from 0.5 to 2.56 per years. The food consumption rate was estimated about 101.56 per year Mixd trophic level index (MTI) showed small pelagic fishes as prey, have crucial role in feeding of pelagic predators population such as invasion of the ctenophore Mnemiopsis leidyi, bream fish and benthic fish such as sturgeon. In general, niche overlap was greater in more species such as Alburnus chalcoides, Rutilus rutilus, Clupeonella cultriventris, Rutilus kutum and M. leidyi who consumed large amounts of plankton. In conclusion small pelagic fish exert a major control on the trophic dynamics of the Caspian Sea ecosystems and constitute midtrophic-level populations.

The main goal of the current study is to evaluate the impact of dietary herbal appetizer on the growth performance of growth out shrimp. This project was conducted at Caspian sea research institute of ecology from 2014 to 2016. Totally 180shrimps with an average weight of 2 g were randomly distributed to 9 fiberglass tanks with area and depth of 1m^2 and of 0.6 m. The experiment lasted for eight weeks and the shrimp were fed by three different diets as follows: 1. Commercial pellet contained no herbal additive (control diet) 2. Commercial pellet contained 1% herbal appetizer and 3. Commercial pellet contained 2% herbal appetizer. The results showed that prawn weight gains for diet 1 , 2 and 3 were 6.28, 5.68 and 6.07 respectively. The estimated growth rate was 2.34g for control diet, 2.22g for 1% inclusion of the additive and 2.28g for 2% inclusion of the additive. Results also showed that inclusion of the additive did not change statistically average final weight (p>0.05). A larger weight gain was observed at 0% additive inclusion although this was not statistically different with other treatments. In conclusion, with regard to the observed results, herbal appetizer administration cannot improve growth, feed conversion rate and weight gain in common carps.

The ichthyology studies at fish tagging was referred to more than 100 years ago. Tagging is utilized for the estimation of stock amount, population frequency and project or calculating of survival and growth value. There are many various methods for fish tagging are used for juvenile to adult fish. The current study was carried out at Ghare-su research station during 2011-2013. 250 of carp fingerlings (Cyprinus carpio) were tagged by bath with tetracycline manner (pH=6, 500mg/l). The fork length and weight of fish were 10-12 mm and 2-4 g, respectively. Also, fish were fed twice a day. The second and third tagging stages were performed at November 2012 and July 2014, respectively. After otolith was extracted, it was washed water and dry at lab room air. The tagged rings or loops (annuali) were observed by lab loupe with 10X and 40 X magnifications. The results showed that a narrow band was formed after the first tagging of carp fingerlings, as it was seen at the end of otolith edge. It was demonstrated that tetracycline was absorbed and the tagged ring or loop (annuli) was newly formed at external or out of othlith edge. There was not observed any fish death, when carp fingerlings were tagged by OTC bath manner. It said that the first OTC band will be seen, the first sign of the formed OTC band was observed at external margin of otoilith after 6th month , of course , from 4th month, this sign was formed at the most external of otoilth edge but with added the following region, it can be hardly distinguished. The formed band in relative to second tagging was similar to the first band but there was no discrepancy or difference with together.

The main goal of the current study is to evaluate the impact of dietary herbal appetizer on the growth performance of growth out common carp. This project was conducted at Caspian sea research institute of ecology from 2013 to 2014. Totally 186 common carps with an average weight of 126.3 g were randomly distributed to 9 fiberglass tanks with area and depth of 16m2 and of 0.6 m. The experiment lasted for eight weeks and the fish were fed by three different diets as follows: 1. Commercial pellet contained no herbal additive (control diet) 2. Commercial pellet contained 1% herbal appetizer and 3. Commercial pellet contained 2% herbal appetizer. The results showed that common carp weight gains for diet 1 , 2 and 3 were 51.6, 49.3 and 57.6g respectively. The estimated growth rate was 39.03g for control diet, 40.03g for 1% inclusion of the additive and 48.65g for 2% inclusion of the additive. Results also showed that inclusion of the additive did not change statistically average final weight (p>0.05). A larger weight gain was observed at 2% additive inclusion although this was not statistically different with other treatments. In conclusion, with regard to the observed results, herbal appetizer administration cannot improve growth, feed conversion rate and weight gain in common carps.

This study was conducted to determine growth parameters, catch and fishing effort trends, stock assessment and Acceptable Biological Catch (ABC) of Caspian Sea mullets in the Iranian coastal waters of Caspian Sea in the fishing season of 2012-2013. For gathering of data on biometry and catch statistics, 5 mobile working group in the regions of Anzali, Kiashahr, Nowshahr, Babolsar and Torkmen were involved from the start to the end of fishing season.Gathered data Were entered to the computer. For data analysis, common methods were undertaken for estimation of growth parameters, mortality rates, biomass and Maximum Sustainable yield (MSY) and Acceptable Biological Catch (ABC) as well. According to the result, the number of beach seines cooperatives was 124 and fishing efforts were 45260 beach seining haul. The catch per unit of effort CPUE) was calculated 37 kg/haul during this fishing season. The total catches of Caspian Sea mullets (including illegal fishing estimated as 2151 mt. Growth parameters of golden gray mullet (Liza aurata) were estimated as K=0.12 /yr, L_∞=59.24 cm, t_0 = - 1.31 /yr. Based on catch-at-age data, in the fishing season of 2012-2013 , the total biomass, from the biomass-based cohort analysis were estimated 11321.6 mt. The reference points of F0.1 and F30% were estimated 0.3 /yr . based on these results , the fishing mortality rate in fishing season of 20122013 were very closed to these reference points. In this survey , the Maximum sustainable yield and Acceptable biological catch were estimated as 2207.7 and 1981.4 mt respectively .Results of biometry of leaping gray mullet (Liza saliens) showed that the mean length and weight of this species were 28.8 ± 3.4 cm and 230.5±74.8 g respectively. Based on these results and due to decline of golden gray mullet stocks, it is recommanded to reduce fishing effort and harvest keep to the level of MSY and ABC .The study of spawing condition of golden gray mullet in new situation of this species is also recommanded.

Environmental pollution by heavy metals has been a matter of growing concern over the last decades. Heavy metals are toxic and tend to accumulate in living organisms. In many studies, fish has been used as a sampling item to monitor the quality of ecosystems because of two reasons: 1- Fish bio-concentrate and integrate contaminant load both in time and space leading to more representative results compared to water samples, and 2- Fish represent the bio-available fraction of environmental contaminants, unlike water and sediment samples. On the other hand, humans consume fish species which makes attention to these fauna even more important. Levels of some metals in the water running in Volga River, towards the Caspian Sea, and elevated concentrations of some trace elements have been reported in sediment. Also, various pollutants have accumulated in the Caspian Sea due to effluents from coastal catchments and leakage from offshore oil production and land-based sources. ... The objective of the present study was to investigate the concentrations of chromium (Cr), cadmium (Cd), cobalt (Co) and lead (Pb) in fish muscle in the most commercially important fish species of kilka (common kilka, C. cultriventris, anchovy C. engrauliformis and bigeye kilka C. grimmi) in the Caspian Sea.

The purpose of this study was to investigate the possibility of natural reproduction of indanger fish in the southern Caspian Sea in Tajan, Haraz,Sardabrood and Chalos rivers, and identify suitable habitats for this species in the study area as a genetic reserve.Sampling of physical and chemical parameters of water, macrobenthic invertebrates and fish fauna was conducted seasonaly in each rivers at selected stations from febrary 2010 during one year. Macrobenthic invertebrate sampling were used bySorber sampler and fish was collected by gill net and electroshocker set with a voltage of 1.7 A and 100-300 V. A total of 53 taxa of macrobenticinvertabrateshave been identified in the four mentioned rivers, in which Tajanriverconsisted of 47 taxa with highest richness.20 species of fish were determined in the studied rivers that 6 of them were non-native species.The results showed that the predominant identified fish species were native in the river. The fish species diversity increases as one moves from the headstream towards the estuaries of the two studied Sardabrud and Chalus rivers.The results of this study showed that the relative abundance of fish species resistant to pollution and hard environmental conditions were much more that sensitive species. physicochemical parameters of water such as; water temperature, DO, BOD5, pH, TSS, TDS, EC, turbidity, nutrients, biodiversity index such as Shanon index, EPT, HFBI, EPT/CHIR, nutrition functioning group and present or absent of fish species showed that there are significant decrease in water qualities from upstraem ratio to down stream (For example, in Tajan river water turbidity varied from 0 at station 1 to 333 NTU at station 6, Which is strongly influenced by sand workshops. As well as the activities of a significant impact of fish farming workshop on the Haraz river water quality). The minimum of HFBI index was 2.84 at station 1 and the maximum was recorded at station 5 with 6.01, and there is not any possibility to natural reproduction of migrated species that are dominant and indanger at downstream. Conditions for natural reproduction of this species in the rivers of srdabrood and Chalus there is to some. In Shahid- Rajaei dam the maximum relative abundance of fish species belonged to Capoeta capoeta, Luciobarbus capito and Squalius cephalus, respectively. These species have different age, length and weight stuctures at Shahid- Rajaei dam inhabitant, and the resourval of this dam and it,s upstream have been preparing auch a favorabile condition that seems there are potentioal of introductionand inhabitant of some of the Migratory and indanger fish species such as Barbels, Sturgeon, Alburnus chalcoides and etc. as genetic reserve for biodiversity preservation.

This study was conducted to determine growth parameters, catch and fishing effort trends, stock assessment and Acceptable Biological Catch (ABC) of bony fishes in the Iranian coastal waters of Caspian Sea in the years 2013-2014 and 2014-2015. According to the result, the numbers of beach seines were 124 and 120 and their fishing efforts were observed 44688 and 46299 beach seining, respectively. The total catches (including illegal fishing) were also obtained 17144.3 mt and 16733.2 mt during 2013-2014 and 2014-2015, respectively. The highest proportion of catch was belonged to kutum and golden grey mullet (94.4% and 89.5%, respectively) in two fishing seasons mentioned above. Growth parameters of kutum were estimated as K=0.19/yr, L_∞ =61.3 cm, t0=-0.99/yr. The Growth parameters were K=0.18/yr, L_∞= 61.1 cm, t0= -0.14/yr for golden gray mullet and were K=0.14/yr, L_∞= 70.8 cm, t0= 0/yr for common carp. Based on catch-at-age data, in the years 2013-2014 and 2014-2015, the total biomass, from the biomass-based cohort analysis were estimated 46900 mt and 41000 mt for kutum and 11550 mt and 12670 mt for golden grey mullet, respectively. The reference points of F0.1 and F35% were 0.41/yr and 0.34/yr for kutum and 0.36/yr and 0.33/yr for golden grey mullet, respectively. According to catch of species/groups, three main groups can be divided easily. The one–way ANOSIM catch similarity test indicated that coverage rates of different years were homologous and similar, but the coverage rates of different months, regions and periods were not similar. Also, there were significant differences in community composition of fishes in catch of beach seines among three times; three durations; three regions and seasons (in all cases MRPP, p

The main objectives of the present study were to estimate of biomass and maximum sustainable yield of common kilka in Iranian waters of the Caspian Sea. This paper examines the maximum sustainable yield (MSY) and fishing intensity at MSY (fMSY) and then using by fMSY, yield-per-recruit and spawning biomass-per-recruit under various harvest strategies of Fmax, F0.1 and F40%; the acceptable biological catch (ABC) was estimated. The results showed that the catch of three species of kilka were 24080 and 22969 t in 2012-2013 and 2013-2014 in Iranian waters of the Caspian sea, respectively and common kilka predominated with 98.1% and 98.9%, respectively. Growth parameters were estimated as L_∞=141.8 mm, K=0.297 yea^r−1, t_0=−1.048 year^−1. The ages of common kilka comprised 6 age groups, ranged from 1 to 6 years and Age groups 3 and 4 years old had the highest frequency. In the years 2012-2013, the catch of age 1 and age 4 represented the lowest and highest proportion of total catch (133.6 and 9121.6 t). In 2013-2014, followed the catch of age 1 and age 3 had the lowest and highest proportion of total catch (151.9 and 8700.2 t). The instantaneous coefficient of natural mortality was estimated as 0.506 year^−1 and total mortality and the instantaneous coefficient of terminal fishing mortality were 0.894 and 1.40 year^−1 respectively. In the years 2012-2013 and 2013-2014, the biomass of common kilka was estimated 90700 and 83300 t, respectively. Also, the fishing mortality was 0.622 and 0.894 year^−1 and the exploration rates were 0.551 and 0.636. The reference points of common kilka at F0.1 and F40% were estimated 0.92 and 0.80 year^−1, respectively. According to Schafer model the MSY and fMSY were estimated 22670 t and 8690 vessel×nights (a unit of effort). In 2013-2014, the ABC of common kilka was estimated 17500, 20060, 23500 and 18900 t in tiers 2, 3, 4 and 5, respectively. However, for the implementation of a precautionary management approach the lower and more accurate ABC-value, based on more information, should be selected and thus the catch should be restricted to 17500 t.

Mullet and mullet products have considerable economic importance at a regional level, especially around the Caspian Sea. The leaping mullet constitutes an important part of their production. This study is the first detailed work on the age and growth of the leaping mullet (Liza saliens) from September 2012 to March 2013 in the Southern coast of the Caspian Sea. Age and growth determinations were based upon the scale samples taken from 102 fish. Marginal increment analysis was used to validate age determination. The back-calculated lengths stage estimated from the scale showed no differences between in this study. The maximum age of leaping mullet in the Southern coast of the Caspian Sea was 5 years for males and 6 years for females. The von Bertalanffy growth functions were Lt=30.415(1-e-0.275(t+0.645)) for males and Lt=34.832(1-e 0.211(t+1.009)) for females. A large spread and length overlap characterized the age groups. The estimated Length Weight relationships were common for the two sexes (W=0.079L3 ). The slope (b) values of the length-weight relationship showed that weight of leaping grey mullet in Mazandaran increased associated with length in isometric. The mean condition factor for males, females and all specimens were determined as 0.908, 0.900 and 0.897, respectively. According to sex groups, the mean condition factor of males was slightlyhigher than that of females. The total length for leaping grey mullet was determined as 23.3 cm.

Dam reservoirs have important rules in aquaculture and fish farming in many countries. In this regard, water samples of Azad Dam reservoir (Sanandaj) were collected at five stations from July 2015 to June 2016. Then, the results of 18 physico-chemical parameters were compared with the aquaculture standards and thresholds. Results showed that thermocline and oxycline was started from June and they vanished in December. Maximum level of thermal and oxygen stratified were registered during August and June, respectively. Mean of the most physico-chemical parameters were significantly different between surface and bottom layers (T-Test, p

In this study genetic characterization of Barbus brachycephalus caspius, Lucioperca lucioperca, Rutilus rutilus caspius, Rutilus frisi kutum and Salmo trutta caspius were examined by 611 samples from regions in East (Guilan province), Middle (Mazandaran province) and west (Golestan province) of southen part of the Caspian Sea. DNA was extracted from fin tissue by phenol -chlorophorm method and then PCR was performed using special primers. Statistical analysis of data was performed by Gene Alex, MEGA and Arlequin softwares. -Rutilus frisi kutum: The results showed that nine of ten primers were polymorphic loci. The mean of effective and observed alleles were 7.26±0.49 and 4.37±0.35 respectively. Also, the mean of expected and observed heterozygosity were 0.55±0.03 and 0.69±0.02 respectively Of the analysed loci, all of the samples (except Tajan and samples in LOC4 and Gilan samples in MFW2) possible tests were found to deviate significantly from the Hardy–Weinberg equilibrium (P

The aim of this project is to study the growth and age structure in the Caspian trout, comparison with other coldwater species and check the trend of these parameters in recent years. This study was conducted during 2013 till 2015. Totally, 43 specimens for back calculation and 101 specimens for biometrical study of the Caspian trout have been caught in two month period. Biometric parameters such as length, weight and age of the fish were recorded. Base on Back calculation method in 1393, the average length of fish at ages 1, 2 and 3 years old were 18.98 ± 3.5, 30.5 ± 7.24 and 41.7 ± 9.1 cm. So these age groups are under the adult age and don’t approaching to near the beach and rivers for spawning behavior. Therefore, these length groups cannot be observed in catch composition. The result showed, the mean of gonad weight in this fish was about 11 percent of total weight and number of eggs per gram of gonad calculated about 10.8 numbers. Minimum age and maximum age of this species determined 4 years and 7 years (mean = 5.6) and the most frequency allocated to 5 age group and the frequency of 6 and 7 years has been remarkable. The average length of salmon was 69.2 ± 6.2 cm (minimum 57 and maximum 81 cm) and the average weight was measured 3323 ± 677 g (2400 to 5600 g) in the catch composition. Growth parameters such as k, L_∞ and ø’ was measured 0.18, 104 cm and 3.289 respectively. The amount of b for relation length and weight was 2.9 which imply negative allometry. L_∞ and growth coefficient (K) on the Caspian trout were acceptable range, that it shows good growth the fish in the sea water. Most of the fishes were catched from Cheshmehkileh River. As at present Shilat uses just the broods of the Tonekaboon region for restocking of this species, we recommend using the broods of the western region separately for rehabilitation of the stocks of this region.

After the arrival of the invasive species (Mnemiopsis leidyi) in the Caspian Sea (in 1999) significant changes have been occurred in the ecosystem. In the present study, the data concerning the period 1996 to 2010 (extracted from the relevant research projects) were analyzed. The period was classified into two phases, before and after the species invasion (1996 and 2001-2010). In our study, the impact of the invasive species on the structure of southern Caspian zooplankton communities was assessed during the period 2001-2010, quantitatively. The combination of abundance and distribution range of the species (ADR) during the period 2001-2009 and the year 2010 were evaluated as E (occurrence in high numbers in all localities) and D (occurrence in moderate numbers in all localities), respectively. Considering the obtained results, the year 2001, in which the relative biomass was more than 90 percent, could be considered as the expansion phase and the following years (2002-2010) as the adjustment phase. With regards to the loss of the keystone and some other native species after the invasion of M. leidyi (2001 to 2010), the impact of the invasive species on the structure of southern Caspian zooplankton communities was assessed as massive (C4).

Present study analyzed the stomach contents of individuals belonging to five fish’s species in order toInvestigate seasonal changes in feeding strategy and diet composition in the South coast of the Caspian Sea (Gilan and Mazandaran provinces) from late March until late May 2010 using the research ship Gillan and fishing with batoom trawl nets and fishing blades insoles bony fishes in the depths of less than 60 meters. The average length and the total weight of Rutilus frisii kutum, Rutilus rutilus caspicus, Cyprinus carpio, Liza auratus and Liza saliens respectively were 36/9 ± 8/5 cm , 562/9 ± 353/2 g, 23/2 ± 3/2 cm , 202 ± 101/6 g, 24/6 ± 8/1 cm , 249/8 ± 242 g, 32/2 ± 8/9 cm , 320/9 ± 242/8 g, 22/7 ± 2/6 cm and 82/9 ± 52/2 g repectively. Using the method of Shorygin and Costello highly nourishing food strategy and different species of fishes were studied. The results of this study showed that Rutilus frisii kutum fed generally of Balanus and Cerastorderma In order of importance after Bivalvia, Gastropoda, Crabs, Fish eggs, Filamentous alge in GI Rutilus frisii kutum presence, but feeding it of Bivalvia (in particular Cerastorderma) was much more than the other food. The results of present study showed that under the influence of compatibility and behavioral mechanisms, ecological, physiological and nutritional importance of Rutilus frisii kutum Bivalvia. The results of studies were showed that Bivalvia was feeding the dominant Rutilus frisii kutum , while the results of this study showed that despite Bivalvia present importance in feeding the of this species, it seems that its presence in such digestion decreased. As well as the dominant food of Rutilus rutilus caspicus was fish, but generally from Detrite fed. This study showed that feeding the dominant species of Cyprinus carpio, Liza auratus and Liza saliens of Detrite was. The most important food items after ditrit for the Cyprinus carpio in order of importance include the Bivalvia, Gastropoda, Oligochaeta, Abra ovata, Nereis, Fish eggs, Filamentous alge, was. The Liza auratus dietary habits also showed that after ditrit the most importance in nutrition related to Foraminifera, Porifera and Balanus, and for Liza saliens to Gastropoda, Bivalvia and Porifera. The results showed that the mullet the greater the intensity of feeding fishes than other species were, Rutilus frisii kutum in between of Cyprinidae the greater the intensity of feeding fishes than other species were (0/05 > P). The values of this indicator in the lower longitudinal in all fish species investigated were more than high longitudinal groups. The feeding intensity at different times of sampling for all species investigated showed that in all species at times extremely reduced the reproductive index (0/05 > P). As well as the diversity foods in the lower longitudinal in all fish species investigated were more than high longitudinal groups. In conclusion, our results demonstrated Food strategy have changed based on physiological changes, metabolism activity, behaviour, and the amount of food available.

This study was to assess the silver carp diet compositionduring grow out period. The experiment was conducted in a well-managed fish farm located at Mazndarn province from 2012 to 2013. Totally five samples from the pond water and also silver cap intestines were collected in May, April, Jun, July, August and September of 2012. The results showed that there are five phyla of phytoplankton in the ponds including: Phyrophyta, Bacilluryophyta, Cyanophyta, Clorophyta, Oglenophyta. A comparison of phytoplankton populationindicated a significant differences throughout the five sampling sessions (P

Big-scale sand smelt is one of the fishes with high ecological value, which consume by fishes such as sturgeon in the Caspian Sea. In this study, 191 samples of Big-scale sand smelt from southeast coast of the Caspian Sea were collected seasonally from December 2013 to September 2014. In the present study, food items and the relative index of gastrointestinal (RLG), stomach emptiness index (VI) and feeding intensity (IF) were determined. The fork length, weight and age (mean ±SD) were 7.70 ± 1.09 cm, 3.64 ± 1.49 g and 2.00 ± 0.81 year, respectively. This fish with a relative gastrointestinal tract length of 0.46 ± 0.06 (mean ± Standard Deviation) can be considered as a carnivorous fish. The average of empty stomach was 45% showing big-scale sand smelt is a relatively voracious feeder. The average intensity of feeding (mean± Standard Deviation) 535±221.21, as a moderate level for this fish in the region. Gammarus (benthos) and Daphnia (zooplankton) were the favored food for this fish. This study also showed opportunistic hunting activities of this fish.

This survey was conducted from Babolsar to Bandar-e-Torkaman in the southern part of the Caspian Sea. Specimens were collected from commercial catches (Beach seine net, mesh size 5 mm). Sampling was carried out monthly (from Sep. 1993 to Sep. 1994) to evaluate the biological characteristics, including total and fork length, weight, age, gonad weight and sex. The results indicated that the scales and operculum were suitable for determining the age though the operculum gave better results than the scale. Since the first annulus has not appeared on the scale and it is very difficult to distinguish annuli on the scales of old specimens. This study also shows that the maximum growth rate is belong to the age of 3 years. The b value regression between fork length and weight was 2.940. The relation between scale radius and circuli number, and growth were: C = 4.609 R 0.8282, L_(t) = 322.4 [1-exp^(-0.361(t+0.013))]. Sex ratio was 1:3.14 and female dominated. The Gonadosomatic Index (GSI) indicates that the spawning activity occurs on July-August. Males ripen earlier than females. Furthermore the numbers of circuli in different ages and condition factor (k) relation between total length and fork length and between age and weight were obtained.

This study was to investigate the possibility of pellet production for grow out common carp considering attractiveness and stability of the pellets. The experiment consisted of two periods and was conducted at the Caspian Sea ecology research center in 2011 and 2012. In period one, two types of pellet with similar protein level (31%) and different energy contents (3000 and 3500 cal/g) were formulated by the ingredients used in fish feed industry. In period two, 316 juvenile carp with initial weight of 27.9g were assigned randomly to 9 fiberglass tanks (4×4×1 m), with three replicates for each treatment. The fish were fed by three diets throughout the eight weeks study, two diets were formulated in the current study and third one was a commercial carp diet with 25% protein. The results showed that feeding with diet containing 31% protein and 3500 cal/g energy led to a feed conversion ratio of 3, but this value was recorded 1.9 for commercial diet. The type of diets was also influenced (P

Caspian Kutum (Rutilus frisii kutum, Kamensky 1901) is among the main commercial species in the Caspian Sea. The present study aimed to determine the spatial and temporal distribution patterns of Kutum in depth ranges of 10 to 100 m by bottom trawl net in Iranian waters of the Caspian Sea during 2008 to 2010. The results showed that the maximum catch and CPUE were 2903 kg and 57.08 kg/0.5 h in winter 2009. The minimum catch and CPUE were 79 kg and 1.41 kg/0.5 h in spring 2010. During the warm seasons (spring and summer) most Kutums occurred in depths less than 20 m. While, during cold seasons they occurred at all depths. The average (±SE) CPUE was 94.0 ± 78.53 kg/0.5 h in depths 20-50 m in autumn and 128.3 ± 77.64 kg/0.5 h in depths >50 m in winter.

The project of the Study on fishing and resource management of fisheries within Southern Caspian Sea was conducted on the base of an agreement made between fisheries organization (Shilat) and the Iranian fishery research organization (IFRO) signed in 2010. In this library-based study the current situation of bony fish fisheries and biology of these species has been surveyed in Iranian waters of the Caspian Sea . In this survey internal and external environmental factors of bony fishes activities were considered. Using SWOT analysis method, current situation of fisheries was investigated..One of the most important strategies for conserving anadromous species such as Caspian kutum , common carp, roach, bream and …. is rehabilitation of the natural spawning ground in rivers, coastal lagoon specially Anzali lagoon .By conducting this strategy not only restocks of bony fishes is done ,but also reduced the cost of artificial restocking programs and releasing fingerlings .In short term , it is nessesary to enhance the stocks of the species that have low catch is done by huge releasing of the fingerlings and study the qualification of the program.

The beach seines catch and effort data from 1996 to 2011 categorized in four periods and used in this research. Geographical coordinates of beach seines determined by portable GPS and distribution maps of important and commercial species prepared by catch per unit effort (CPUE). The concentration of beach seines in the western coast of Golestan province, Kiashahr area and eastern part of Anzali was more than another part. The daily effort in Kiashahr and Anzali area was very high, thus the fishing stress in these areas was more than another part of Iranian coastal waters of the Caspian Sea. The number of species in catch composition increased from east to west and the beach seines of Guilan province had total of commercial species, but the number of commercial species rarely was five species in Golestan province and especially in eastern coast. Relative frequency and distribution of Kuttum in the east Babolsar area and then between Sepidroud and Anzali lagoon were more than another part. The ISI index of Kuttum was high in all of the area except east coast of Golestan province. The main distribution of Mullets determined in the western coast of Golestan province and the Amirabad fishing area and in these areas, the ISI index of Mullets was high. The main distribution area of common carp determined in east coast of Golestan and the ISI index of common carp was very low in other parts. Density and distribution of Kolmeh were high in eastern and western coasts of Iranian waters of the Caspian Sea and the density of this species was very low in Mazandaran province. The density of Zander was very high in surrounding of Sepidroud River and Anzali lagoon. The ISI index of commercial species in Guilan province was more than other provinces except Kuttum, mullets and common carp.

The main objective of the present study was qualitative and quantitative assessment of anchovy stock, Clupeonella engrauliformis in Iranian waters of the Caspian Sea during (1995- 2011). Over this period, total catch of anchovy kilka increased from 32000 tonnes in 2005 to 67000 tonnes in 1999 and decreased sharply to 80 tonnes in 2011. In the years 1995-1999, catch per unit effort (CPUE) was fairly constant (2.92-3.52 tonnes/(Vessels×Nights) which fell to 0.01 tonnes/(Vessels×Nights) in 2011. Total biomass and spawning stock biomass (SSB) had the same trend as CPUE. During 1995-1999, total biomass of anchovy kilka ranged between 158500-185900 tonnes which dropped to 2000 tonnes in 2007. The SSB showed a downwardtrend from 105500 tonnes in 1997 to 1950 tonnes in 2007. In age compositions of the catch, age 3+ was the largest age group. From 2001 to 2003, age 2+ predominated. Finally, number of young specimens declined and age 6+ and 7+ groups were predominated in the last years. Present study indicated that the situation of the anchovy kilka is critical. A coordinated international effort is needed to provide implementation of sustainable management and responsible fishing activities in the whole Caspian Sea.

The project of the Study on fishing and resource management of fisheries within Southern Caspian Sea was conducted on the base of an agreement made between fisheries organization (Shilat) and the Iranian fishery research organization (IFRO) signed in 2010. The study has several phases. The final report of the fishery on fishing and resource management of fisheries within Southern Caspian Sea (Gilan, Mazandaran & Golestan provinces) is consisted of several sections such as: 1- The Survey status of biology and catch of Kilka fishes , Bony fishes and Estrogen fishes and also the status of aquatic resource conservation in the Southern part of Caspian Sea 2- Fishing analysis in the Southern part of Caspian Sea 3- Fisheries development Strategies, policies and plans in the Southern part of Caspian Sea In this survey and library-based study, internal and external environmental factors of shilat activities are considered. Using SWOT analysis method, current situation of fisheries is investigated. In this regard, all fisheries activities were divided into four groups, then, the strengths, weaknesses, opportunities and treats of internal and external environment will be analyzed. A considerable number of tables and matrixes were prepared and policies and strategies as seen of final report were carried out.

The main objective of the present study was qualitative assessment of Caspian kutum (Rutilus frisii kutum Kamensky 1901) stocks by using indicators of overfishing, condition factor and relative weight in Iranian waters of the Caspian Sea during a long period (1991- 2011). Three fisheries indicators in catch were: 1) percentage of mature fish, with 100% as target; 2) percent of specimens with optimum length, with 100% as target; and 3) percentage of mega-spawners, with 0% as target, and if no upper size limit exists, 30-40% as representative of reasonable stock structure. Over this period, the condition factor and relative weight had a decreasing trend. The range of length with optimum yield was between 40 and 48 cm. The mega-spawner measured as fish a size larger than 48 cm. According to these three indicators, the percentage of mature (fork length>40cm), optimum size and mega-spawners were 62.0, 40.9 and 12.5% in 1991-92 which decreased less than 50, 38.2 and 8%, in the years 1992-2011, respectively. The length structure is a matter of concern. Therefore, for reservation and rebuilt of kutum in the Caspian Sea, the target was to let all (100%) fish spawn at least once, using bigger mesh size in cod end (e.g. 35mm, during whole fishing season). The aim was also to implement a fishing strategy that result no (0%) mega-spawners being caught, and the main catch focus on optimum length.

Reproduction period, spawning peak and sexual maturity in anchovy kilka were investigated during the year 2006 for sustainable yield assessment in Iranian waters of the Caspian Sea. The mean fork length, total weight and age were 118±5.9mm, 11±1.7g and 4.6±1.2 year, respectively. Mean (±SD) absolute fecundity was 12625±5533 ovules. More than 50 percent of the fish specimens matured when their length exceeded 92.5mm. The results showed that reproduction of anchovy kilka occurred in autumn, and spawning occurred throughout the year and especially in winter. The length and age ranges were found to be shortened compared to the past years with many older fish and less younger ones (< 2 years) in the catch which sharply decreased recruitment. This phenomenon is thought to be due to overfishing synchronized with invasion of M. leidyi pushing kilka to spawn in winter, which all cause collapse of anchovy kilka stocks in the Caspian Sea. We postulate that anchovy kilka has adopted the strategy of spawning year round to mitigate the negative effects of overfishing and invasion of M. leidyi.

This paper aimed to investigate the fishery and biological characteristics of anchovy Kilka in Iranian waters of the Caspian Sea from 2005-2007, including length and age structure ,Von Bertalanffy growth parameters, length and age at first capture, condition factor, sex ratio, natural and fishing mortality. The examination of catch data approved that Kilka population in the Caspian Sea have been declined a few years ago following entrance jellyfish Ctenophora Mnemiopsis leidyi. The greatest destruction of anchovy kilka catch was occurred while the catch of anchovy from 4250 tonnes in 2005 reached to 924 tonnes in 2007. The results showed that K value and L∞ calculated 0.375/year, 131.7mm, respectively. The instantaneous coefficient of natural mortality was estimated 0.49/year. The instantaneous coefficient of fishing mortality and total mortality was 0.51/year and 1/year, respectively. The Exploitation rate was calculated as 0.51. The length and age ranges restricted comparison to last decade and sharply decreased recruitment. In the past few years, the main reasons of disintegrates among anchovy Kilka stocks in the Caspian Sea were synchronized overfishing competitive anchovy Kilka with M. leidyi.

Recently, the ecology of the Caspian Sea coastal has undergone with increasing development of human activities and industrial wastewater discharge. Therefore, considering the current situation, evaluate of pollutants issue in the Caspian Sea is very important. Results of this study showed that levels of heavy metals (Cd, Cr, Cu, Fe, Pb, and Zn) of water had lower than standard and also acceptable for aquatic life. Significant accumulation of metals such as Co, Cu and Cr in the sediment was observed at transect Sefidrood and Anzali in comparison with six other transects (Turkmen, Amirabad, Babolsar, Noshar, Tonekabon and Astara) and for Ni at transects Sefidrood and Astara compared with six other transects (Turkmen, Amirabad, Babolsar, Noshahr, Tonekabon and Anzali) (P

During the past decades the environmental status of the Caspian Sea has changed. Therefore, study on the biological structure such as: age, growth, Lm50%, feeding of fishes is necessary. In the present study the biological characteristics of some commercial important species including kilka, kutum, golden grey mullet and carp were studied during 2006-2010. Kutum, golden grey mullet and carp predominated in the catch composition of bonyfishes, representing 61.3, 29.6 and 7.6% of the total catch. The average fork lengths of kutum, golden grey mullet and carp were 38.4, 32.7 and 36.7 cm, and weights were 784.5, 411.0 and 977.0 g, respectively. The values of b in length-weight relationships were 3.02 and 2.97 for kutum and golden grey mullet indicating an isometric growth. The value b for carp was 2.89, indicating an allomertic growth. The maximum age of three species was 12 years. Von Bertalanffy growth equations were estimated as: for kutum: for golden grey mullet: and for carp: The sex ratio of three species showed that females were dominant. Spawning migratory of kutum was started in March. The gonadosomatic index value of kutum peaked in March and April. The spawning season of carp expended from March to August. The gonadosomatic index value of golden grey mullet peaked in September and then declined in November and December. Absolute fecundity of kutum, golden grey mullet and carp were 64400, 700800 and 131000 eggs, respectively. Length maturity (Lm50%) of three species were 39.07, 28.4 and 31.6 cm, respectively. The highest feeding intensity (Gastrosomatic index=GSI) for females and males were 313.9 ± 65.9 and 350.7±103.7 in October; and the lowest value of GSI were 19.4 ±59.2 and 144.1±85.04 in March, respectively. There are significant different between GSI with male and female in difference months (P

In the years 2007-2007, 2008-2009 and 2009-2010 the exploitation of bony fishes resources (by 131 beach seines) started on 12 October but finished on 9 April, 9 April and 13 April, respectively. During these periods the total catch of bony fishes were 23537.8, 20045.5 and 18664.8 tonnes, respevtively. During these periods, kutum predominated and represented the highest proportion of total catch at 73.1, 74.0 and 66.9% , followed by golden grey mullet at 18.3, 13.9 and 18.7%, respectively. K values calculated 0.22, 0.15 and 0.14 year-1 and L∞ were 66.0, 62.7 and 70.0 cm for kuttum, golden grey mullet and common carp, respectively. The instantaneous coefficient natural mortality were estimated as 0.386 and 0.35 year-1 for kutum and golden grey mullet, respectively. During three periods, the exploitation rates were 0.789, 0.584 and 0.614 for kutum and 0.71, 0.75 and 0.61 for golden grey mullet, respectively. In the years 2007-2007, 2008-2009 and 2009-2010, the total biomass, from the biomass-based cohort analysis were 56600, 62090 and 61590 tonnes for kutum and and MSY estimated about 24733.7 and 8550.4 tones for kuttum and 11040, 11900 and 14460 tonnes for golden grey mullet, respectively. The ABC (acceptable biological catch) were estimated as 8000 and 2200 tonnes.

The intensive culture of common carp (Cyprinus carpio) evaluated in fibreglass tanks (2*2m) with feeding on pellet during 8 weeks. The fish (n=201)of common carp selected from three treatments along with three replicates as the average of fish weight was less than 100(g )which divided into 0.05).The common pellet food was chosen for feeding from market as fish were fed by the mean of 4% of their body weight a day. The result indicated that the mean of particular growth ratio at first treatment (0.54) has higher than second treatment (0.34) but in comparison with third treatment (0.46), there was no statistically significant difference (P

Annually, many data of hydrology and hydrobiology of the southern Caspian Sea at Iran's coasts were collected by Caspian Sea Research Institute of Ecology. The data which had been collected by researchers submitted annually in several reports but has not been processed all at once. Fluctuations of various parameters were surveyed and the relationships between them were analyzed. The main goal of this research is to analysis the data were obtained from 1994 to 2006 and show changes the concentration of various parameters in the Caspian Sea. Physicochemical data indicated that the average trend of transparency and salinity was decreased from 1994 to 2006 annually, where the salinity value was decreased from 12.37 ppt (part per thousand) to 11.5 ppt. The average of dissolved oxygen was increased from 6.4 to 8.6mg/l. pH has slightly fluctuated from 8.15 to 8.31. However, with increasing depth from surface to bottom, the average of dissolved oxygen was sharply decreased (DO concentration in surface and 800 m was 7.18 and 1.45 mg/l, respectively). The trend of salinity and pH fluctuation was very slow with depth but the salinity has an increasing with incrementing of depth but pH has a decreased trend. The average of organic and inorganic phosphorus and TP was nearly increased. The average of Nitrate and Silica sharply increased comparing to depth but the average of Nitrite and organic Nitrogen decreased. The results showed that the temperature fluctuation in different water layers was low in winter but the dramatic decreasing of temperature was occurred at 10-20 m (in spring), 20-50 m (in winter) and 50-100 m (in autumn). With increasing of depth (Slope of the Sea), transparency and salinity values have an increasing while DO and pH showed decreased. As a whole, 335 species of phytoplankton were identified, there are 70 species in advance as these species were not seen in this period but 96 of novel's species have been recorded. The lowest and the most of phytoplankton biomass was recorded in 2006 and 2001 while the biomass was 59 and 1034 mg/m^3, respectively. Albet, the lowest biomass was recorded at the depth of 100 m (24.1 mg/m^3) but the maximum was observed in surface layer (1344.1 mg/m^3). The average of phytoplankton biomass was increased after arrival of the ctenophore. There was a significant difference between the average of biomass in different seasons before and after of the ctenophore invasion (P0.137, P>0.782). Before the presence of ctenophore, the worms had been constituted a dominate group with an approximately %45 of total abundance and also %20 of their biomass. After this period, their frequency was sharply increased (more than %85) but the maximum value pertains to Cardidae (more than %90). The species diversity, evenness and richness were varied between .69-2.51, 0.23-0.63 and .011-3.79, respectively. AMBI software, Shanon-Viner parameter was moderate in all seasons from 1994 to 1996 but this parameter was reduced in a bad limit (boundary) in the most seasons from 2002 to 2005. The main parameter of M-AMBI consists of several parameters and also approximately showed similar changes such as Shanon -viner parameter. On basis of this parameter, the ecological quality condition of Caspian Sea was superior limit in all seasons from 1994 to 1996 but after the following years were decreased from good to moderate limits (After the presence of ctenophore). Relationship between abiotic variants and phytoplankton indicated that there was a direct relationship between transparency and salinity while there was a powerful and reversal significant relationship between transparency water temperature, transparency in organic Nitrate, phytoplankton number and transparency phytoplankton biomass. The comparison between different variants average in two periods (before and after the ctenophore invasion) indicated that the average of Kilka catch was decreased, the relative frequency of clupeonella engrauliformis and clupenoella grimmi was sharply reduced but the relative frequency of Clupeonella cultriventris was sharply increased, the species diversity, evenness and richness and the number of zooplankton species were sharply decreased, the average of biomass and transparency was sharply reduced, the average of dissolved oxygen and liza saliens or liza auratus catch were increased. These difference were often significant (P

The aim of the present study was to investigate the age structure, length-weight relationship, sex ratio, sexual maturity stages, growth parameters, natural and fishing mortality coefficients of three species of kilka including common, anchovy and bigeye kilka. The fork length–weight relationship of common, anchovy and bigeye kilka were calculated as W=0.000153 FL2.37, W=0.000349 FL2.18 and W=0.00160 FL2.97, respectively. The parameters of the von Bertalanffy growth curve for length were L∞ = 143.5 mm, K = 0.30 yr-1 and t0 = -1.02 yr for common kilka L∞ = 151.9 mm, K = 0.28 yr-1 and t0 = -1.12 yr for anchovy kilka L∞ = 148.6 mm, K = 0.46 yr-1 and t0 = -0.18 yr for bigeye kilka. The instantaneous coefficient of natural mortality of common, anchovy and bigeye kilka were estimated as 0.671, 0.633 and 0.881 yr-1, respectively. The current exploitation rates of three species were estimated as 0.55, 0.41 and 0.26, respectively. The results suggest that common kilka stock is under over-fishing now.

Seasonal distribution of species composition, cell abundance and biomass of phytoplankton of the Caspian Sea were investigated in 2005. This survey were fulfilled in 6 transects and 26 stations A total of 260 samples were collected during winter to autumn in the southern part of Caspian Sea. Totally, 163 species of phytoplankton were identified (71 species Bacillariophyta, 31 species Chlorophyta, 27 species Cyanophyta, 21 species Pyrrophyta, and 13 species Euglenophyta). Cell abundance and biomass of Bacillariophyta were high in centre, while biomass and cell abundance of Pyrrophyta were dominant in the middle as well as parts of the Sea, respectively. The overall total average of cell abundance and biomass of phytoplankton were 56.30± 30.97 ×106cells/m3 and 221.70±75.87 mg/m3, respectively. Bacillariophyta accounted for 47% in cell abundance, and Pyrrophyta consisted of 53% of the phytoplankton biomass. Maximum phytoplankton population was recorded in winter due to Bacillariophyta and the maximum biomass in spring due to Pyrrophyta. The maximum density of Bacillariophyta was in winter and autumn while maximum biomass was observed in spring due to bigger size of Bacillariophyta such as Rhizosolenia calcar avis and Nitzschia sigmoidea followed by Pyrrophyta with high cell abundance throughout the year.

The project of Age, growth, feeding regime and fecundity of Kutum (Rutilus frisii Kutum) survey started in south of the Caspian Sea from 2006 to 2007. The aim of project was related to determination of length maturity (Lm50%), identification of feeding animals, and investigation some of biological aspects uncluded in sex ratio, growth and age structure in southern of the Caspian Sea. Total 2706 specimens of Kutum were surveyed. The age structure of Kutum has nine age groups that included in 1, 2, 3, 4, 5, 6, 7, 8, and 9 years. The result showed that maximum frequency was about 39.3 % and were belong to 4 years and minimum frequency which was about o.1 % were belong to 9 years. The maximum and minimum fork length and weight were 58 and 21cm with mean (±SD) 38.4 (± 6.4) cm; 2450 and 104g with mean (±SD) 784.2 (± 383.30) g , respectively. There are significant different between fork length and weight in male and female of Kutum at difference months (ANOVA, P

We evaluated the stocks of Huso huso in the south Caspian Sea along Iranian coasts using data on different population parameters such as length, age, weight, catch and catch per unit effort changes. The study covered data from 1971 to 2003. The stocks and catch rate of H. huso shows a decrease during the last three decades. The recorded catch for the years 1971-1972 was 74 tons with 5.55kg catch per unit effort which was decreased to 38 tons with 0.26 kg per unit effort in 2003 in gillnet fishery and the same trend was observed in beach seine fishing. The data shows that during 1990 to 2003, the average length of the fish has increased from 192.8 to 216.2 centimeters and the average weight has improved from 73 kg to 116.3 kg. Age frequency comparison between the catch of the years 1990 and 2003 showed that with time, older age classes replaced the younger ones, hence the increase in the length and weight of the fish. Due to the decrease in the younger fish and the increase in illegal fishing, it is anticipated that the fish stocks will suffer a decrease in future.

The spawning season, fecundity rate, male to female ratio and Lm _ (50) of the Caspian Sea common kilka (Clupeonella cultriventris) were investigated during March 2005 to February 2006 in the coastal waters of Mazandaran province. The mean fork length and the weight of ovary females were 99.47 ±9.8mm and 8.3 ±2.0g respectively. The sex ratio was 2:1 in which females were dominant. The common kilka spawning started from January and its peak occurred in May. The mean gonadosomatic index was 2.1 ±6.0mm and its maximum was estimated at 0.28 and 8.9 respectively with its highest recorded in May. The condition factor was calculated at 1.5 ±0.12. More than 50 percent of the fish specimens matured when their length exceeded 94.17mm.

Menmiopsis leidyi was entered into Caspian Sea from Black Sea and mass population constitutes in the southern Caspian Sea. In this surveys, the relationship between length and wet weight measured and length and weight followed by this equation: n=384, R^2=0.87 w=0.003L^9005 . The relationship of dry and wet weight calculated, in this surveys, the ratio of dry weight to wet weight was equal to 1.615% in 12 salinity. In vitro, the clearance rate at 12 and 27 C were 52.48 and 107.33 ml/h, respectively, daily ration at above temperatures were 1.98 and 16.65 respectively. Mnemiopsis leidyi can feed Acartia in accordance to 16.5 mg/1gbw (body weight) at 27 C in one day. The average digestive time in 12 C and 27 C were 77.50 min and 36 min respectively. The digestive value in 27 C was 2.5 fold than 12 C. The result indicated that clearance rate, daily ration and digest were increased in high temperature. Stomach content of Mnemiopsis leidyi was shown that this organism utilized from Acartia and Balanus, in addition, stomach content of kilka including two species of zooplankton from the southern Caspian Sea. Stomach contents of clupeonella cultiventris contain more than 54 percent of Acartia and its nauplii. This frequency observed in cluponella engrauliformis and clupeonella grimmi. On basis of zooplankton sampling in the sea, over 90 percentage of zooplankton populations contain Acartia.

This project has been started as monitoring study since 2001 that in first phase has lasted for two years and because of its importance, it was decided that this study should be continued for two other years. In the early 1980s, an alien ctenophore Mnemiopsis leidyi already known as a gelatinous zooplankton was transported (likely via ballast waters) to the Black Sea from its native waters of the western Atlantic. The possibility of Mnemiopsis leidyi introduction into other sensitive, neighboring ecosystems, notably the Caspian Sea, had been mentioned during the GESAMP meeting in 1994. And, as expected, this ctenophore was reported to be present in the Caspian Sea by November 1999. In this report, spatial and temporal distribution of M. leidyi had been investigated in southern Caspian Sea (Iranian waters) in 6 transects consisted of Lisar, Anzali, Sefidroud, Nowshar, Babolsar and Amirabad at 24 stations during 2003 and 2004. As a whole, 818 samples had been analyzed included 236, 302, 136 and 144 belong to ctenophore, phytoplankton, zooplankton and benthos. Meantime 811 physicochemical parameters had been measured. Water temperature varied between 7.8 to 29.3 co. Transparencies also fluctuated from 0.20 to 10.5 m. Salinity in different regions was from 7.80 to 13.90 ppt and the average was 12.09 ppt. pH was between 7.2- 8.6. Demand oxygen (O2) has been measured very high in water surface (12.89 µg.l) and it decreased at minimum level in deep down to 4 µg.l. Nutrients measurements such as NO_2, NO_3 and NH_4 were 0.10-15.17 , 3.80- 133.40 and 0.36- 86.40 µg.l, respectively. Total nitrate and phosphate were measured between 337.00- 1635.00 and 14.90-103.40 µg.l, respectively. Comparison of M. leidyi distribution in the southern Caspian Sea shown that maximum abundance recorded in warm summer months (e.g. August) with 11627 ind.m^2 and its biomass maximum was in autumn months (September and October) about 446.11 gr.m^2 . Mean abundance and biomass of M. leidyi were 2504 ind.m^2 and 142.42 gr.m^2, respectively. Maximum size of the ctenophore recorded as 70 mm while the less than 10 mm length frequency consisted 92.2 per cent of total population. Spatial distribution of M. leidyi in different regions shown that Sefidroud not only had the maximum Mnemiopsis abundance but also consisted higher biomass in the southern Caspian Sea in 2003-4. At present study, 142 phytoplankton species were identified which belongs to Chrysophyta (67, 48), Chlorophyta (23, 16%), Cyanophyta (22, 15%), Pyrhophyta (21, 15%) and Euglenophyta (9, 6%). Mean phytoplankton abundance and biomass were 11137032 ind. m^3 and 40.26 mg. m^3, respectively. Chrysophyta (diatoms) consisted 42 and 47% of whole phytoplankton abundance and biomass. In the other hand, this group included 50 % of phytoplankton population. In zooplankton study, there were identified 21 species in which 10 species were only meroplankton (zoobenthic) and 11 species was holoplankton. These species belongs to Copepoda (4, 37%), Rotatoria (4, 36%), Cilliophora (2, 18%) and Cladocera (1, 9%). Monthly zooplankton abundance and biomass data shown that its population completely effected by Copepoda. Among copepoda, Acartia clausi was the main species duri ng 2003-4. As a whole, maximum abundance recorded in spring (March) and autumn (September) about 11497 and 11321 ind. m^3 while its maximum biomass occurred in summer (August) with 48.95 mg. m^3. Zooplankton minimum abundance and biomass were in wintertime about 3894 ind. m^3 and 10.16 mg. m^3. Benthic fauna in recent study consisted 27 species included Gammaride (8, 29%), Cumacea (7, 26%), Polychaeta (4, 15%), Bivalvia (3, 11%) and Oligochaeta, Balanidae and Xantidae each one (4%) species. Mean benthic abundance and biomass were 1215 ind. m^ 2 and 20.09 g. m^2, respectively. Polychaeta and Oligochaeta were established maximum frequency about 49 and 34% of total fauna while Bivalvia consisted 82.8% biomass overall.

This paper examines the changes in the population biology and biomass of common kilka (Clupeonella cultriventris caspia) in the Iranian waters of the Caspian Sea from 1995-2004. For most years during this 10-year period, we estimated the age structure of the catch, length-weight relationship, von Bertalanffy growth parameters, condition factor, sex ratios, maturity stages determined from ovarian analysis, natural and fishing mortality, age at first capture and biomass. Growth parameters were estimated as L∞=132mm, K=0.259/yr, t0=-1.285/yr. The instantaneous coefficient of natural mortality was estimated at 0.506/yr and the instantaneous coefficient of fishing mortality varied during the 10-year period between 0.125/yr to 1.487/yr. Biomass of the common kilka increased from about 16,000mt in 1995 to more than 41,000mt in year of 2002. This increase in common kilka was simultaneous with a sharp decline in anchovy kilka, changes in zooplankton abundance and composition, and especially increase in zooplankton species used by common kilka. We concluded that at the present time, the stock of common kilka is being over-fished.

Biological and reproduction characteristics of female big-eye kilka (Clupeonella grimmi) including body weight, fork length, age, gonad development stages, gonad weight, ganado somatic ratio (GSR) were studied. We sampled 808 fish specimens from the Southern Caspian Sea, Babolsar Area during December 2002 to May 2003. Gonad development stages were assessed through tissue sectioning. Results revealed spawning peak to occur in early January. We also measured body weight as 8.88±0.08 grams, fork length as 1.03±0.26 mm, age as 3.610.03 years, gonad development stage as 3.67±0.03, gonad weight as 0.5±0.01 grams and ganado somatic ratio (GSR) as 5.39 ±0.1 in the specimens. Totally, five age classes, dominated by the 4+ years were distinguished while no 1+ year's age class was observed. The abundance of gonad developmental stages 2-5 was 18.19%, 14.60%, 48.89% and 18.32% respectively. Macroscopic (visual) and microscopic (tissue section) observations of oocyte revealed the same results for gonad development.

Kilka, a pelagic fish feeding on zooplanktons, are the most abundant fish genus in the Caspian Sea. There are three species of the fish living in the Sea including anchovy (Clupeonella engrauliformes), bigeye (C. grimmi) and common kilka (C. cultriventris). All three species live in the coastal waters of the Sea and comprise part of the commercial catch in the area. The relative frequency of the bigeye ranked second after anchovy over the years 1990-1991 with 6.84% increasing to 12.6% and 21.7% over the years 1997-1998 and decreasing in the subsequent years. We studied biological characteristics of the bigeye kilka over the years 1997-2001 in three fishing regions Amirabad, Babolsar and Anzali. In winter and earlier spring of each year, mature bigeye kilka ready to spawn were always present in the catch. The mean fork length of the fish increased from 95.87mm in 1997 to 105mm in 2000 and decreased to 102.3mm afterwards. Over the same time period, the fork length range became wider with specimens in the upper length classes representing most of the catch. We found that males were always dominant during our study comprising 60 to 90% of the catch. The caught fish consisted of six age classes 1+ to 6+. During the years 1998 to 1999, the age Classes 1+ to 3+ comprised more than 90% of the catch. In the year 2000, we observed a decrease in the age classes 1+ and 2+ and an increase in the age classes 4+, to 5+ compared to that of the previous years. In the year 2001, the age classes 3+ and 4+ decreased and the age classes 5+ and 6+ increased. In recent years, the relative frequency of the bigeye kilka has decreased as a result of the attack by the Mnemiopsis leidyi, but fork length range of the fish has increased and bigger and older fish are dominant in the catch.

In an attempt to recognize the harmful fishing times and locations for sturgeons, we used catch statistic to evaluate by-catch of sturgeon juveniles during beach seine fishing over the years 2001-2002 in Mazandaran Province. We found that over the fishing period, 23760 hauls were conducted during which 103000 sturgeons were caught. The highest by-catch occurred in October (37% of the catch) and the lowest occurred in January (5% of the catch). The maximum sturgeon catch per haul was 14.2 in autumn decreasing through the year with 1.26 sturgeon fish caught in each haul in spring. The species composition of the by-catch sturgeon juveniles was determined to be Persian sturgeon (54%), Stellatus sturgeon (37%), Beluga (6%), Russian sturgeon (2%) and Spiny sturgeon (1%).

Mullet and other bony fishes are caught by beach seine in Iranian coastal zone in Golestan, Mazandaran and Guilan provinces. The catch and CPUE trend of mullets were compared during 1993 to 2001 and some biological characteristics such as: species composition, length, weight, K and age of Liza aurata and L. saliens were analyzed. In 1990s, the results showed that amount of catch has been increased and the maximum catch occurred in 2001. CPUE decreased from 114 kg (in each seine) in 1993 to 43 kg in 1996 whereas 2001 increased to 66.4 and 78.4 kg in 2000 and 2001, respectively. The mean fork length, weight and K for L. aurata species were measured 32.7 and 32.3 cm, 418.3 and 419.8 g and 0.61 and 0.93 and for L. saliens species were 27.5 and 25.1 cm, 224.7 and 179.1 g and 0.91 and 0.71 for years 2000 and 2001, respectively. According to this data in spite of increasing in catch, CPUE of L. aurata has increased and there are no changes in respect of biological aspect. Therefore, it was concluded that this species is harvested of a sustainable level.

The alien ctenophore Mnemiopsis leidyi which was transported from the Black Sea into the Caspian Sea at the end of 1990s has been negatively affecting ecosystem in this new environment. In this study, spatial and temporal distribution of M.leidyi were studied from a total of stations located along three transects (Amirabad, Babolsar and Nowshar) in the Eeastern Iranian coasts of the Caspian Sea (Mazandaran province) during July 2001 to November 2002. M. leidyi acheived maximum biomass 1024.5 g/m^2 in August-October 2002. Minimum biomass (1.5 g/m^2 of ctenophore were measured in December-Jaunuary 2001. The highest biomass was at the stations with 10m bottom depth (570.7 g/m^2 in autumn and lowest biomass (75.9 g/m^2) was obtained at a station with a 50 m bottom depth in winter. The highest average biomass (641.2 g/m^2) were measured in ~irabad region and the lowest biomass (207.5 g/m^2) observed in Nowshar region. The young specimens (