Age, growth and some biological characteristics of Silver bream (Blicca bjoerkna L., 1758) (Cyprinidae) from Aras Dam Lake in Northwest of Iran

We collected Silver bream Blicca bjoerkna from March to July 2013 from Aras Dam Lake (North-west of Iran) and investigated its age, size, and some biological characteristics. The maximum age was 5+ years. The total length and weight of specimens ranged 137-278 mm and 26-247 g for male and 134-282 mm and 26-289 g for female, respectively. Length-weight relationship was estimated as W = 1E-06TL3.44 for females, W = 1E-06TL3.45 for males and W = 1E-06TL3.44 for the sexes combined. Sex ratio was 1:1.42 in favor of males. The growth model was positive allometric for males, females and sexes combined. The calculated maximum condition factor was 0.34 in male and 0.37 in female. The most frequent age classes in the samples were 2+ years for males and females

Benthic community structure in the Gorgan Bay (Southeast of the Caspian Sea, Iran): Correlation to water physiochemical factors and heavy metal concentration of sediment

Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae), Arthropods (Pontogammaridae, Balanidae and Chironomidae) and Mollusks (Cardiidae and Scrobicularidae). Lumbriculidae (413 individuals m-2, corresponding to 18.7%) and Cardiidae (55.2 g m-2, corresponding to 82.4%) had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show unsimilar relationship with heavy metal concentration

Growth and mortality parameters of Caspian kutum, Rutilus kutum, in southern Caspian Sea

The Caspian Kutum, Rutilus frisii, is one of the endemic and most important commercial cyprinid species in the southern Caspian Sea. A detailed study on growth and mortality parameters of this species was conducted based on 700 samples collected from commercial catches of beach seining in Guilan and Mazanderan provinces during fishing season 2017-2018. Females were dominated in both studied populations. Size frequency distributions showed significant variation among same sexes and between different sexes. The different WLRs were observed, positive allometric in Mazanderan, and negative allometric in Guilan. There were significant differences in growth parameters between sexes, females were of much greater asymptotic length than males, while the male fish had a higher growth rate and attained a smaller theoretical L∞ size than females. The theoretical maximum length (L∞) was larger than the maximum one recorded during sampling. Based on the Bhattacharya method, the Caspian kutum from Guilan fishing grounds was more diverse, and included nine cohorts, while the population from Mazanderan Province showed only six cohorts. The linearized catch curve based on age composition data showed that total mortality rates (Z) are 1.32 year-1 and 0.63 year-1 for males and females of Guilan, respectively, that of males in Mazanderan is 1.04 year-1 and of females 0.86 year-1. The natural mortality rates (M) were 0.48 year-1 for males and 0.26 year-1 females in Guilan, and was found to be as 0.26 year-1 and 0.45 year-1 for males and females of Caspian kutum caught in Mazanderan. The exploitation ratio (E) was found to be higher than 0.5 for both sexes from Guilan, and to be lower than the expected optimum level of exploitation in Caspian kutum males and females caught in Mazanderan

Some reproductive Features of Cobitis sp. from Dough River in the southern Caspian Sea basin

Cobitis sp. is an endemic spined loach species from the Dough River in the southern Caspian Sea basin, (Golestan Province, Iran). To provide some reproductive features of this fish, sampling was performed at monthly intervals throughout the year and 417 individuals were collected. The specimens ranged in total length from 27.1 to 92.9 mm and total weight from 0.11 to 6.79 g. The spawning of spined loach of Dough River occurs from March to June. The highest mean value of gonadosomatic index (GSI) observed in April as 1.96 for males and 6.61 for females. Egg diameter ranged from 0.3 to 1.3 mm, with a mean value of 0.9 mm. Absolute fecundity varied from 155.04 to 3212 eggs. Fecundity relative to total weight fluctuated from 55.41 to 634.76 eggs g–1. This species is among those spawning early in spring compared to other species of this genus from southern Caspian basin

Population dynamic of the oriental river prawn (Macrobrachium nipponense) from Golestan Dam Lake – Golestan Province

Oriental shrimp is an exotic species widely distributed in northern Iran. This study was conducted to determine the population dynamic characteristics of this species based on the specimen caught in Golestan Dam lake from February to September 2016. The sex ratio was unbalanced in favor of females (1:1.88). Total length and weight ranged from 16.06 to 85.01 mm and 0.04 to 6.75 gr, respectively. There were significant differences in relative abundance and mean weight among various months. Mean length and weight for males (mean TL = 42.26 mm and W = 1.12 gr, respectively) were larger than that of females (mean TL = 41.15 mm and W = 0.99 gr, respectively). Growth pattern was positive allometric for both sexes (bfemale = 3.16, bmale = 3.15). Condition factor varied significantly among months and between sexes as well. Von Bertalanffy growth equation was Lt = 87.5(1-e-0.85(t+0.14)) for females and Lt = 87.5(1-e-0.9(t+0.132)) for males. Natural mortality was calculated 2.09 for females and 2.17 for males indicating a high mortality rate for both sexes

Age, growth and some biological characteristics of Silver bream (Blicca bjoerkna L., 1758) (Cyprinidae) from Aras Dam Lake in Northwest of Iran

We collected Silver bream Blicca bjoerkna from March to July 2013 from Aras Dam Lake (North-west of Iran) and investigated its age, size, and some biological characteristics. The maximum age was 5+ years. The total length and weight of specimens ranged 137-278 mm and 26-247 g for male and 134-282 mm and 26-289 g for female, respectively. Length-weight relationship was estimated as W = 1E-06TL3.44 for females, W = 1E-06TL3.45 for males and W = 1E-06TL3.44 for the sexes combined. Sex ratio was 1:1.42 in favor of males. The growth model was positive allometric for males, females and sexes combined. The calculated maximum condition factor was 0.34 in male and 0.37 in female. The most frequent age classes in the samples were 2+ years for males and females

Some reproductive biology parameters of mosquitofish Gambusia holbrooki Girard, 1859 (Poeciliidae) in some waterbodies of southeastern Caspian basin, Iran

Eastern mosquitofish, Gambusia holbrooki, is an invasive exotic fish for Iranian inland water. This study conducted to evaluate some reproductive traits of this species in six waterbodies from southeastern Caspian basin. A total of 8500 individuals were sampled from the AlmaGol Wetland, Alakooli Dam Lake, Gomishan Lagoon, Voshmgir Dam Lake, Golestan Dam Lake, and estuary of Gorgan River during February to September 2014. The maximum age in all areas was 1+ for males and 2+ for females. The highest mean GSI value was 2.6 for males in April-May and 29.6 for females in May. Egg diameter ranged from 0.5 to 2.5 mm with a mean value of 1.43 mm. Absolute fecundity varied between 2 to 212 eggs. Both ova diameter and absolute fecundity were positively correlated with females' size, while relative fecundity had no significant correlation with females' size (length and weight). The results showed a significant variations in reproductive characteristics among the populations inhabiting different habitats. This finding is important with respect to life history of the species and ecological view as well

An assessment of electrofishing effects on Capoeta capoeta in a controlled environment (salinity and temperature)

The purpose of this study was to investigate the effect of voltage, salinity and temperature on the performance of electrofishing. Number 850 pcs Capoeta capoeta of Chehel Chay river of Golestan province fishing and transported to the laboratory. Distance from the anode, cathode and anode distance during testing, respectively, 10 cm and the 120 cm. Range of length and weight of the fish test species in order Capoeta capoeta 11.53± 0.61cm and 13.701± 5.303 gr. Electric shocks were applied to the individual fish on the three voltages of 15, 45 and 135 volts and three temperatures of 10° c, 20° c and 30° c and three salinities of 0.5, 2 and 4 gr/liter. Time to anesthesia and recovery were recorded for each fish. Statistical analysis using One-way Anova, Duncan and LSD test. Comparison showed that the average duration of anesthesia voltages and temperatures and the salinities are significantly different. Maximum anesthesia time for Capoeta capoeta abtain from the salinity 2 gr/liter, temperature 10° c, Voltage 15 volt with a mean (7.81±0.88 s) and minimum abtain from salinity4 gr/liter, temperature 20° c, voltage 135 volt, with mean (1.18± 0.09 s). Maximum of the recovery time to Capoeta capoeta abtain from Salinity 0.5 gr/liter, temperature 30° c, Voltage 135 volt with a mean (159.46± 16.17 s) show and minimum abtain from salinity 0.5 gr/liter, temperature 20° c, voltage 15 volt with a mean (44.29±9.11 s)

Benthic community structure in the Gorgan Bay (Southeast of the Caspian Sea, Iran): Correlation to water physiochemical factors and heavy metal concentration of sediment

Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae), Arthropods (Pontogammaridae, Balanidae and Chironomidae) and Mollusks (Cardiidae and Scrobicularidae). Lumbriculidae (413 individuals m-2, corresponding to 18.7%) and Cardiidae (55.2 g m-2, corresponding to 82.4%) had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show unsimilar relationship with heavy metal concentration

Report blue-green algae from the southern coast of the Caspian Sea (City of Noor)

The blue green algae as photosynthetic organisms have a main effect on life and productivity of the aquatic ecosystems. Intensive and longtime studies on identification, distribution, and diversity of Cyanophyta have to be a crucial task in the Caspian Sea. Four transects were determined parallel to the Sabzehrud River, the Lavij River, the Noor River, and the Faculty of Marine Sciences of Tarbiat Modares University from 2014 to 2015. Samples were seasonally collected from three stations in each transect by a plankton net with a mesh size of 55 and the Ruthner's bathometer. Standard hydrobiological and phycology approaches were used for identification and counting abundance of Cyanophyta. The most number of Cyanophyta was observed 1.06 × 106 cells per liter at the station of A1 during summer. Genera such as Chroococcus, Gloeocapsa, Merismopedia, Microcystis belonged to unicellular taxa and Anabaena, Anabaenopsis, Nostoc, Oscillatoria, Phormidium were identified as multicellular genera. At the most stations, Anabaenopsis nadsonii was found as the most encountered species. Overall, Cyanophyta abundance was significantly different among stations in all investigated seasons. The blue green species also did not have same frequency distribution inside of the each transect (Test Chi-Square, P <0.05)