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  • 1
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    Determination of catchability bony-fish and optimized exploitation in the Caspian Sea (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: To accomplish the stock assessment that pre-planned for bony-fish resources investigation started by considering two pivotal act. First gathering biometric data and second using catch statistics information for stock analyses. Implementing the research programmes five itinerant groups in Anzali, Keyashahr, Noshahar, Babolsar, Torkaman have been organized during fishing season. The biometric data were supplied in computer that distincted by each fish species and subdivided into age groups. In analyses the samples, Bertalanffy formula used for calculating average length and age, also for growth coefficient. Total mortality rate calculated by using Pauly formula, and the biomass status estimated through Cohort analysis. The catch by beach seiner cooperatives recorded 8630 metric tons, but estimation including. Poacher catch raised the harvest to 15.6 thousand tons. The total catch of Kutum reduced by 1400 tons compared with previous year, but the estimation revealed the biomass of Kutum 18.5 thousand tones, the stock stowed reduction in quantity relative to past years. Harvest exceeding the limit, fishing pressure. And employing higher fishing effort, combining releasing the Kutum seedling with shorter average length in recent years, leaded the shrinkage of biomass of Kutum resources. The Golden Grey mullet catch has been estimated 3437 metric tons, the figure showed 1500 tons increment, in comparison with previous year, nearly 24% of catch was shorter than Lm50% of this species. In Guilan province higher number of sub - size golden mullet captured, this development occured less in Mazandaran and Golestan province. Higher rate of exploitation, reduction of catch in recent years, dominating small size fish in catch composition indicated the population undergoing stress in ecosystem. Thin - lipped grey mullet only comprised 9.2% of the mullet catch - Length - structure of this fish species population formed mainly by young small size fish, the biomass of latter estimated 1100 metric tons. Catch further than maximum sustainable yield, by higher exploitation rate, and gradual diminishing of harvest, represented the resources of this fish species suffering both by high fishing pressure and un - sustainable effort, which ultimately declined the fishery of this fish species. Carp catch and its resources in Anzali region become very low, it is necessary to enhance the stock by Sea-ranching programmes. The carp resources in Gorgan region enjoy better status, but catch practices do not compatible with rule and regulation in Gorgan and Gomeyshan area. The standing stock of Gorgan carp estimated nearly 6000 tons. The information concerning carp resources indicate the stock experiencing pressure and likely the catch will diminish in future. The total catal catch of carp calculated 1900 tons. In recent years the Caspian roach resources are increasing but the bulk of harvest fished illegally and by gill - nets. The total catch of the roach during 1998-1999 estimated 1700 tons. Considering the semi - artificial propagation of roach in Golestan province, if has been concluded the multiplication of this fish species also should be planned by fisheries authorities for Anzali region. It is also advisable catching of this fish species to be regulated soon and selective catch are proposed. The catch of pike - perch during the year of 1997 - 98 jumped to 95 tons, but 90% of catch formed by young fish or sub – standard length size. Almost, all the increment of catch attributed to the releasing of millions of seedlings in the Sea which the plan has been implemented by Iranian Fisheries. Increasing the numbers of released seedlings, with higher average weight Identification of most suitable site for unloading the fries could ensure better survival rate and contribute the enhancement of resources and produce good catch for this desirable fish species. The total catch of Bream hit 18 tons, but most of the catch comprised by young fish with sub - standard size. The present formation of fisheries population of bream are the result of seedling releasing! In the Sea by Iranian Fisheries, since the catch of bream are negligible despite releasing programmes of seedling in a decade which 14million individuals until now, one could conclude the programmes do not contributed effectively to stock rehabilitation. The Caspian Barbus (Barbus brachycephalus) are at the threshold 01 vanishing, at present a few numbers are caught, therefore B.capito appeared in catch composition. The catch of latter species in recent two years are increasing. Total catch during the year of 1998 - 99 estimated 34.5 tons, biomass calculated 93 tons. Caspian vimba are small size fish which beach seiner (mesh size in bosom 30 millimeters) could not capture them ideally, bulk of the catch caught in illegal manner by gill nets. The total catch estimated 154 tons which the present fishing procedures surpassed total allowable catch (136 tons). In recent years the catch of this fish species are increasing. "Shemaya' similar in size with Vimba are caught less by beach seiner, illegal catch are considerable, the total catch in 1998 - 99 estimated 86 tons. The level of harvesting of this fish species are increasing in recent years and its population size become significant relative to last years. The main part of catch concerning Aspius fish species occured in Guilan coastal area, high fishing pressure reduced the population size, including low discharge of water in rivers during spawning period, impact negatively to reproduction. Catch statistic in 1989 showed 128 tons of this fish species are caught but in 1998 - 99 it has been reduced to 6.8 tons. It has been suggested artificial spawning could prevent its fate as endangering species. Caspian salmon catch estimated 78 tons during 1998 - 99, salmon population in Caspian Sea are supported by releasing reared smolts, which in recent years nearly 500 thousands fingerlings released in suitable rivers. After banning the gil nets application in Southern Caspian Sea, the catch of salmon in beach seining are increasing. It is necessary the released smolts in rivers being protected for its safe approach to Caspian Sea. The total catch of herring fish species in 1998 - 99 were nearly 700 tons. The bulk of the catch occur In Guilan fishing area, elimination of gill - nets usage in Southern Caspian Sea contributed the increment of herrings catch in beach seining. The herring resources in Caspian Sea reduced relative to past decades. The catch during 1913 – 1916 ranged between 130 - 160 thousand tons, in Caspian Sea.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Stock assessment ; Bony-fish ; Fishing ; Species ; Samples ; Growth ; Mortality rates ; Biomass ; Kutum ; Carp ; Survival rate ; Barbus brachycephalus ; B.capito ; Population
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 136pp.
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  • 2
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    Biological studies of fishes (Clupeidae, Rutilus frisi kutum, Liza auratus, Cyprinus carpio, Chalchalburnus chalcoides, Vimba vimba, Abramis brama, Sander lucioperca & Liza saliens) of Southern Caspian Sea (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: 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〈0.05). Main prey mature of Kutum was Cerastoderma lamarki; Gastropoda and Balanus were subordinate, and Crab, Hypanis, Fish (Neogobous sp.) Algae, egg, and scale were random preys. Planktone groups comprise to Exuviaella, Nitzchia, Osillatoria, Synedra, Nematoda, Navicolla, Diatoma, Rholcosphenia were preys juvenile of Kutum. Based on ISI (Important species index), Cerastoderma lamarki and Balanus were dominant species in feeding of Kutum. The percent of empty stomach and prey dominant evaluated during different seasons by specific formula result showed that in Cyprinus carpio prey Molluscs was dominated and specific food items. Empty stomachs in winter and spring were higher and lower, respectively. The results showed that catch of kilka decreased from 22300 mt in 2006 to 16700 mt in 2008, but the CPUE increased from 1.7 mt (Vessel×Night) to 2.5 mt, due to decrease of effort, respectively. The length frequency of three species of kilka is close and the juvenile fish did not see in catch. The age frequency had the same situation as fish lower than 2 years was not in the samples of anchovy and bigeye kilka. The parameters of the von Bertalanffy growth curve were: For common kilka: L =136.5 cm, K=0.249 yr-1 and t0= -1.89 yr-1 For bigeye kilka: L =148. cm, K=0.346 yr-1 and t0= -1.123 yr-1 And for anchovy kilka: L =131.7 cm, K=0.375 yr-1 and t0= -1.243 yr-1 The exploitation rate of anhovy, bigeye and common kilka were 0.51, 0.58 and 0.6, respectively. The highest of GSI for common and bigeye was recorded in May and March, respectively. For anchovy kilka it was in July and November. Main prey of anchovy and common kilka was Acartia tonsa and for bigeye kilka it was Cypris balanus. We concluded that the ecological problems caused by Mnemiopsis leidyi as well as overfishing have been collapsed kilka stocks, particularly anchovy. Therefore, sustainable fisheries management and conservation biodiversity in the Caspian Sea are real challenges now.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Commercial ; Growth ; Species ; Kilka kutum ; Bonyfish ; Sex ratio ; Spawning ; Gonadosomatic ; Maturity ; GSI ; Hypanis ; Neogobous sp. ; Algae ; Nitzchia ; Cyprinus carpio ; Diatoma ; Clupeidae ; Rutilus frisi kutum ; Liza auratus ; Chalchalburnus chalcoides ; Vimba vimba ; Abramis brama ; Sander lucioperca ; Liza saliens ; Fish
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 98pp.
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  • 3
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    Stock assessment of freshwater crayfish (Astacus leptodactylus) in Aras reservoir (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: 360 funnel traps were prepared as 30 in one row. They were bitted and located in different depths in sampling sites. Two rows each composed of 30 traps were located by stone, linking rope and boat with 50 m distance in sampling stations. The results showed that the average of total length of caught crayfish was 106.26±12.89 mm and their mean weight was 38.79 ± 15.54 gr. The largest crayfish had 171 mm length and 216 g weight. Also mean of total CPUE was 9.72±4.49 individuals in the study period. The evaluation by Schnabel approach indicated that fluctuation range of freshwater crayfish biomass with more than 120mm length was 131-313 with an average of 212.59 ±30.23 kilograms per ha. In this study freshwater crayfish biomass with more than 120mm length was 247 × 10^3 kilograms. The Maximum Sustainable Yield (MSY) was estimated 83 × 10^3 kilograms. In this study ّFecundity and biometry of crayfish (Astacus leptodactylus) was investigated during 2012-2013. The results showed that the average of total length of caught crayfish was 106.26±12.89 mm and their mean weight was 38.79 ± 15.54 gr. The largest crayfish had 171 mm length and 216 g weight. Mean number of ovarian and pleopodal eggs were estimated at 286 ± 82 and 246.31 ± 80.41 eggs (with 95% confidence limits), respectively. In this research, male to female ratio was obtained 1.21:1. The time of male moulting at 16° C was started from April and was ended in the late May, when the water temperature reached to 18° C. The second moulting of males and the first moulting of females was performed simultaneously in 18° C water temperature at September. Reproduction of freshwater crayfish was started from November and continued to May of the next year. Harvesting period was from May to late November.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Freshwater ; Crayfish ; Astacus leptodactylus ; Fecundity ; Biometry ; Population changes
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 104pp.
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  • 4
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    The biomass and distribution of Pseudocumidae in the southern-west coasts of the Caspian Sea (Guilan province) (2018)
    Details
    Publication Date: 2021-05-19
    Description: The most part of the fauna population in the Caspian Sea comprised invertebrates that is dominated by benthic organisms. Cumacea belongs to Arthropoda phylum, class of Crustacea and has an important role as food for sturgeon fishes in the Caspian Sea. This study was performed from autumn 1992 to summer 1993 in sixteen transects and each transect had four stations located at 10,20, 50 and 100 m depths. The survey revealed that the maximum mean biomass of this family was observed at 10 m depth in transect 15 with 9.62 gim2 and the minimum was observed at 20 m depth in transect 1 with 0.07 g/m2. The greatest biomass of this family was observed in spring with average biomass of 6.48 g/m2 and the lowest biomass was observed in autumn-winter with average biomass ofl.47 g/m2. The maximum and minimum mean biomass was observed at 100 m and 10 m depths respectively. The average biomass of this benthos had significant differences in different depths and seasons (P〈0.05). The amount of T.O.M had high and considerable changes in different depths with a range of 3.55-10.37% for depths of 10 to 100m, respectively. Also the maximum percentage of sand in sediment was observed in 10m depth with value of 58.64% and minimum value was 34.73% in 100m depth. The mean biomass of this aquatic organism was 4.75 ± o.45 g/m2 in eastren area and 3.59±0.31 g/m2 in western area of this province. Nonparametric statitical analysis of Kruskal- Wallis showed significant diffrence between mean biomass in this two areas (P 〈 0.05).
    Description: Published
    Keywords: Cumacea ; Biomass ; Population ; Arthropoda phylum ; Crustacea ; Survey ; Benthos ; Sediment ; Aquatic organisms
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.29-40
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  • 5
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    Population dynamics and some biological aspects of Palaemon elegans in the Guilan province waters (2018)
    Details
    Publication Date: 2021-05-19
    Description: Samplings were carried out weekly in coastal waters of the Guilan province (Caspian Sea) by a hand net with 0.5mm mesh size during 1996-1997. The results of one year sampling showed that the mean total length(T.L.) of this shrimp (pooled data of females and males) was 28.58±5.58mm (x±SD), and were 26.46±4.30 and 30.01±6.30mm in males and females, respectively. For ovigorus females, mean T.L was 36.16±3.13mm, also the minimum and maximum T.L of the males were 12.6 and 41.1mm, respectively. In females these figures were found 10.7 and 43.4mm, respectively. The length-weight relationship for the males and females were determined as W=0.0002 TL2.97 (R2=92.13) and W=0.00002 TL2.98 (R2=92.84), respectively. Spawning season was determined from May to September. The average absolute fecundity was 796±320, with a range of 360 and 1660. There is a direct retationship between fecundity and T.L. Females provided 59.42% and males 40.56% of the population, the sex ratio deviated from 1:1 (P〈0.05). The growth coefficient of Loa for females, males and pooled data based on powell-wetheral methods were 42.6, 34.4 and 42.5, respectively. The growth coefficient of K based on Shepherd method were 2.1, 2.3 and 2.5 for females, males and pooled data, respectively. Natural mortality rate (M) calculated as 2.29, 2.29 and 2.28 per year for females, males and pooled da1a, respectively. Total mortality rate was calculated as 2.38, 2.50 and 2.61 per year for females, males and pooled data, respectively.
    Description: Published
    Keywords: Population dynamics ; Growth ; Mortality ; Spawning ; Palaemon elegans ; Sampling ; Length ; Shrimp ; Females ; Males ; Fecundity ; Growth
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.109-126
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  • 6
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    Reproduction, sexual maturity and fecundity of anchovy kilka (Clupeonella engrauliformis Svetovidov 1941) in Iranian waters of the Caspian Sea (2017)
    Details
    Publication Date: 2021-05-19
    Description: 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.
    Description: Published
    Keywords: Fishing management ; Stock assessment ; Anchovy kilka ; Clupeonella engrauliformis ; Reproduction ; Sexual ; Fecundity ; Maturity
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.21-32
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  • 7
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    Research on determining of mesh size standard for beach seine fishery cooperatives to boost sustainable Bony-fish fishery in southern Caspian Sea (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: Bony fish stocks are being legally utilized by 134 fishing cooperatives in the Iranian side of the Caspian Sea mainly through beach seine. This fishing method has been invariantly used over the past. Fifty years with actually no alteration or technical modifications in the fishing nets despite the substantial changes in the quality & quantity of bony fish resources. Based on the data obtained from the stock assessment project for bony fish, the amount of premature or young fish (substandard size) caught during the past decade has been far greater than those of authorized fish size and even the figures far certain species suggest heavy over fishing to such an extent that in the case of frisii kutum, there has been a reduction by 50% in the overall kutum landings.Thus in order to modify the technical design of the fishing with a view to alleviate the catch of non-standard fish and whereby prevent over fishing by beach seine, it seems imperative therefore to launch a biometric study on bony fish stocks particularly the two intended fish species namely Rutilus frisii kutum and mullet which would involve identification of their standard weight and length using pertinent mathematical equations as well as determining proper mesh size of the code-end and other parts of the nets & consequently the H. R, d/a coefficients. The operations related to project were carried out in the "Inland Aquaculture Research Institute" net mating plant and beach seine site in Anzali during 2005-7 which aimed at designing and constructing standardized beach seines and comparing the fishing performance & yields with those of ordinary beach seine nets under equal conditions with a ratio of 3:1. The results concerning the quality and quantity of fish caught during a whole fishing cycle were recorded in the related data forms. The statistical analysis consisting the comparison of the quality of fishing performance in both the experimental and control beach seine nets was made using T. student and excel, spss 12 software packages. The results indicated that the reduction in the amount of non-standard fish caught in standardized beach seine net (the experimental net) was meaningfully different from that of the ordinary (control) net showing the superior fishing performance of the former. The catch level of non-standard R.frisii kutum decreased from 67.1% in the control beach seine net down to 7.1% in the standardized beach seine net and these figures for mullet were 29.98% and 1.1% respectively. Based on the results obtained and considering the apparent superiority of the experimental net in catching greater number of mature fish and less number of premature or non-standard sized fish, the use of this modified beach seine net can be proposed to Iranian fisheries organization as a viable alternative to the traditional beach seine nets.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Beach seine net ; Rutilus frisii kutum ; Mullet ; Standard sized fish ; Non-standard sized fish ; Bony fish ; Fishing ; Stock assessment ; R.frisii kutum
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 84pp.
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  • 8
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    Study of Golabar dam reservoir in Zanjan province (Zanjan Province) (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: The limnological study of the Golabar dam showed that in the Glabar dam inspite of bing its early establishmeant due to high nutrient and organic matter is located in eutrophic stage. the pH as well as bicarbonate levels shows that buffering capacity of the lake is high and the value of inorganic and organic matter measured are not considered as limiting factor for warme and cold water aquaculture.In the plankton survey 44 species of phytoplankton and 25 species of zooplankton were identified.Cyclotella , Nitzschia, Synedra and Trachelomona from phytoplankton and Polyarthera , Keratella , Filinia , Pompholyx from zooplankton were the dominant spicies.the Bacillariophyta from phytoplankton with 76.5 percent and Rotatoria zooplankton to with 76.2 percent considered the highest abundant . the average frequency of phytoplankton and zooplankton were 5*106 and 723 individual per litter. The Shironomide and Tobificide were the only two bentic group were identified in reservoir wehre their mean frequced were 293.75 and 224.30 respectively.The average biomass of bentic organism were 1.44±0.97 gr/m2.In the survey 12 species of fishes were identified.The potential natural production have been estimated to be 2.8 to 15.5 kg for bentivorous fish and varied from 53 to 175 kg /hec for plankton consumer fishes .The low temperature in several months as well as ice covered of the lake surface in particular in the months of duty and Bahman are the limiting factor of either warm or cold water fish production.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Golabar dam ; Nutrients ; Phytoplankton ; Zooplankton ; Fish ; Benthic
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 74pp.
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  • 9
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    Studying distribution and biology of Neogobius caspius in Guilan province coasts (South Caspian Sea) (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: The Caspian goby, Neogobius caspius, is an endemic species of Gobiidae family in the Caspian Sea and it has ecological importance (as food for Caspian commercial fish such as sturgeons). The main aims of this study are, studying distribution, length, weight and age structure, sex ratio, diet, reproduction biology and morphological characters of this species in Guilan coast at waters of the Caspian sea and the sampling has been done monthly from Oct. 2005 to Sep. 2006 in 4 station from Astara to Chaboksar, with bottom trawl which had 12.5 meter length, 4.7 meter gape width and 2 mm mesh size in code end. The results showed N. caspius abundance is 9.82±11.93% of Gobiids and 7.92±10.10% of total fish numbers sampled in the study area (13824 specimens belong to 16 fish species) and there were significant differences among stations and seasons. CPUA of N.Caspius was estimated 52.5±105.9 ind/hec and 412.7±770.7 g/hec and there were significant differences among stations and seasons. Maximum body weight, total length and age were measured 65.10 g, 176 mm and 6 years old with an average 8.74±9.9 g, 84.83±28.4 mm and 1.83 years old, respectively and maximum age of males and females was 6 and 5 years old respectively and there were significant differences among stations and seasons and between sexes. It was estimated algometric growth model from length-weight regression, coefficient of K Von Bertalanffy growth model was estimated 0.42 and 0.68 in male and female, respectively. Sex ratio was 1.27 female to 1 male. Coefficient vacuity, relative gut length and intensity of 169 fullness were 8.72%, 0.76±0.17 and 267.7±263.3 for, respectively and Caspian goby fed on 30 different prey consist Zooplanktons (8 types), Benthic animals (15 types) and fishes (7 types) and young and yearlings have fed mainly mixed food (zooplankton and benthic animals) and adults on zoobenthose. Gammarids, Bivalvia, Cumaceae and Vormes constituted 44.7, 38.9, 24.8 and 19.7 % of prescence in full-gutted samples respectively, they were mainly preys (number and weight), hence this species is considered as euryphagus, carnivorous, benthphagus species. It was determined, Caspian goby spawns from March until last June, males and females take part in spawning in 2.8g and 65 mm and 1.3 g and 52 mm, respectively. Length at 50% maturity (LM50) was 80.2 and 77.5 mm in males and females, respectively. Maturity took place at 2 years old for both sexes, too. The absolute fecundity was estimated 109-1350 (451.6±216.3) eggs and relative fecundity 18-80 (36.8±9.2) eggs per one grams of body weight and diameter of ripe eggs was measured 1.31-2.60 (2.18±0.19) mm. Morphologically, there were 15 morphologically significant statistical differences between males and females and 15 differences among stations, sexual dimorphism was observed, too.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Ecological ; Commercial ; Biology ; Morphological ; Neogobius caspius ; Caspian goby ; Distribution ; Population structure ; Diet ; Reproduction ; Morphology ; Gobiidae ; CPUA ; Algometric ; Zooplankton ; Benthic
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 169pp.
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  • 10
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    Distribution pattern and biomass estimation of benthic invertebrates in Aras reservoir (2018)
    Details
    Publication Date: 2021-05-19
    Description: This study was carried out at monthly basis covering six sampling stations in Aras reservoir in 1995, The samples were collected by Ekman grab with 3 replicates, The results Showed that Oligochaetes were the dominant taxa in this reservoir which were observed all year round and had the highest abundance and biomass, The Chironomidae were the second dominant family. Gammaridae and Mysidae had the least abundance and biomass, Maximum biomass of Oligochaetes was observed in spring with the average figure of 19.03 g/m2 and minimum biomass was observed in winter with average biomass of 5.87 g/m2 Maximum and minimum biomass or Chironomidae were recorded in summer and spring, of which their correspond average biomass were 1.52 and 0.06 g/m2, respectively. The highest and lowest biomass of Mysidae family were observed in summer and spring with the average biomass of 0.46 and 0.00 g/m2, respectively. Gammaridae family observed only in summer. The differences of biomass of these 3 families were significant based on kruskal-wallis nonparametric test (p0.05). Maximum (26.06 g/m2) and minimum biomass (3.14 g/m2) of benthic organisms were observed in stations 4 and 5, respectively and no remarkable variation was observed in the percentage of total organic matter (TOM) content during different seasons. Maximum and minimum average percentage of TOM were 6.66% to 4.79% in spring and winter, respectively. Based on collected data and obtained results, it can be assumed that feeding of fishes, sediment composition, amount of TOM and water temperature were the most important factors effect on temporal and spatial variation in population and biomass of benthic organisms of Aras reservoir.
    Description: Published
    Keywords: Biomass ; Benthic ; Samples ; Oligochaetes ; Chironomidae ; Gammaridae ; Mysidae ; Organisms ; Temperature ; Distribution ; Benthos ; Invertebrate
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.1-10
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