Distribution pattern and biomass estimation of benthic invertebrates in Aras reservoir

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 (p0.05). 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

The biomass and distribution of Pseudocumidae in the southern-west coasts of the Caspian Sea (Guilan province)

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)

Investigation on meiofauna and substrate characteristic in the southern Caspian Sea (Guilan Province)

Meiofauna with a size of 100-1000µ having important rule in food webs. This study was carried out in autumn and winter 1992 along 30 transects at depths of 10, 20, 50 and 100m. The sediment samples were collected by grab (0.1 m2 area). In addition to identification of meiofauna, the sediments were examined to determine T.O.M. and grain size parameters. The results showed that bivalvia, foraminifera, nematoda, ostracoda and copepoda were dominant taxa among 12 identified fauna groups, in which foraminifera and bivalvia were the most abundant. The nonparametric Kroscall-walis test showed significant difference among abundance of meiofauna in different depths. The depth of 20m had the most abundance and with increasing depth (5O and 100m), the abundance had a descending trend. The maximum and minimum mean abundance of meiofauna varied from 29315±37248 and 825±498 ind/10 em2 for depth of 10 and 100m, respectively. The substrate characteristics indicated that the depth of 50 and 10m included the most and the least organic matter. Also all depths indicated the same grain size and sediment composition was mostly silt. Most of meiofauna were found in substrates with 4 to 8 % organic matter

Population dynamics and some biological aspects of Palaemon elegans in the Guilan Province waters

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

Changes in stocks of anchovy kilka, Clupeonella engrauliformis in Iranian coastal zone of the Caspian Sea (1995-2011)

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

Reproduction, sexual maturity and fecundity of anchovy kilka (Clupeonella engrauliformis Svetovidov 1941) in Iranian waters of the Caspian Sea

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

Determination of catchability bony-fish and optimized exploitation in the Caspian Sea

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 gill 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

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

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 anchovy, 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

Conservation and restoration of Caspian salmon (Salmo trutta caspius) stocks in the southern Caspian

The project is funded by the CASPECO Project which is the Third Phase of the GEF supported project in the Caspian Sea region titled “The Caspian Sea: Restoring Depleted Fisheries and Consolidation of a Permanent Regional Environmental Governance Framework”, and implemented by the Iranian Fisheries Research Organization (IFRO) in partnership with four Coastal Research Centers affiliated to IFRO, Coldwater Fishes Research Centre (CFRC).The project's objective is to improve the conservation and restoration of Caspian Salmon (Salmo trutta caspius) stocks. In accordance with IUCN criteria Caspian Salmon is placed in the red list of endangered fish. In the recent decades the destruction of habitats for juveniles, reduction of genetic diversity and fish immune system were main causes of the Caspian salmon decline. Numbers of public meetings were held with participation of fishing communities’ representatives, experts, relevant local authorities and experts of the IFRO and Iranian Fisheries Organization (IFO), Iran Environment Protection Organization (IEPO), Water Resource Management (Ministry of Energy) and University senior professors, in order to create interaction and understanding of the project objectives. Educational awareness and extension program were conducted with the involvement of fisheries communities, private sector and NGO associations. The results of the project suggests that cross-sectoral coordination for sustainable fisheries can be achieved through building partnerships and enhancing communication between the environment, private, fisheries sectors and academia. Cross-sectoral cooperation through this project improved public awareness on growing risks facing Caspian Salmon from different sources including local sources (illegal fishing and over-fishing, urban wastewater, environment destruction, industrial pollutants, pollution of air and water resources), new emerging and invasive organisms, climate change, implications of the Caspian salmon population decline on economic and social affairs of the people who depend on them for their livelihood and food security and their role in fish stock protection. The project, through its capacity building, extension and educational programs and efforts to link science to management, could translate scientific findings into an action agenda for managers and policy makers that can bring an improvement in the future of the Caspian Sea salmon stock

Age, growth, feeding regime reproduction and sexual maturity of Rutilus frisii Kutum in Iranian coastal waters of Caspian Sea

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<0.05). The sex ratio of males to female was 0.65: 1 (males: females). The least and high condition factor was 1.5 in January and 2.17 in October, respectively. Length maturity (Lm50%) was 39.07cm. Minimum and maximum absolute fecundity was varied from 15713 to 130737 eggs with mean (±SD) 69961.7 (± 3836.4). Significant different was between absolute fecundity with fork length and weight (p<0.05). Gonadosomatic index (GSI) mean for females were 2.5±0.2 (autumn) and 17± 0.2 (spring); 1.2± 0.1 (autumn) and 4.1± 0.2 (spring) for males, respectively wich coincided to spawning period. The highest feeding intensity (Gastrosomatic index) for females was 313.9 ± 65.9 in October and 119.4 ±59.2 in March; 350.7 ±103.7 in October and 144.1±85.04 in March for males, respectively. There are significant different between GSI with male anfemale in difference months (ANOVA, p<0.05). The Bertalanffy growth equation for all populations of Kutum was L (t) = 63.92[1-e ^0.19 (t (-1.00)]. 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. As a result, growth, fecundity and length maturity of Kutum declined which may due to loss natural breeding area, overfishing (overlapping between fishing and spawning period) and artificial breeding that commenced since 1982. Hopefully, this information can be used in fisheries management