One of the major sources of impacts on marine resources comes from climate variability and regime... more One of the major sources of impacts on marine resources comes from climate variability and regime shifts. In this context, the present study pinpoints the role of climatic and environmental parameters on the dynamic of kilka in the Caspian Sea. During the last decades, landings and stocks of the main pelagic species of kilka had been changed dramatically in the Caspian Sea. This study focuses on the last three decades of the climate regime and tries to explain the part of the changes in the recruitment (R) and spawning stock biomass (SSB) of three kilka species. Based on the statistical analysis of data series, it is found that regime changes in the global and regional environmental variables started in the mid-1995s, however, the shift of the late 1990s (1998) was more strong in the Caspian Sea. The study further reveals that the global climatic indices changes in the late 1990s are triggering the regional and local indices induced regime shifts in the late 1990s and 2000s. The stu...
This study aimed to investigate the impact of fishing in Iranian part of the Caspian Sea during 1... more This study aimed to investigate the impact of fishing in Iranian part of the Caspian Sea during 1991-2017 years using fishing-in-balance (FiB), mean trophic level (MTI), ratio of pelagic and demersal fish landings (P/D) and piscivory (PI) indices. The mean (±S.D) of MTI were 2.91±0.38 (95% C.I =3.14-2.67). Its value is first reduced and then increase happened and ultimately stays constant. The mean of FiB was 0.13 (95% C.I=0.28-(-0.02)) and its trend was similar to that of total landing. The mean of Pi index, P/D index, pelagic fish and demersal fish were 0.04±0.02 (95% C.I=0.09-(-0.012)), 3.16±2.31 (95% C.I = 0.6-(-0.52)), 38529±22883 (95% C.I=38585-38472) and 13380±3314 (95% C.I= 3401-13358), respectively. The results revealed that the fish stock in the Iranian waters of the Caspian Sea have been over-exploited. Considering that fishing impacts on the trophic level, we suggest that the fishery management should not continue this trend.
Measurements of bioavailability responses in frogs from contaminated sites could provide valuable... more Measurements of bioavailability responses in frogs from contaminated sites could provide valuable data for environmental risk assessment. Biomarkers are sensitive to both e nvironmental pollution and confounding factors that are not related to pollution. The specimens were collected on a monthl y basis from the Babol-River from July to September 2010 to determine if monthly changes exist in condition, he patosomatic index (HSI) and frogs. Fulton condition factor (FCF range: 1.513±0.431 ‐ 1.638±0.473), hepatosomatic index ( HSI range: 3.901±0.504-5.231±1.206), Bioaccumulation factor (BAF), the highest level of copper was observed. Liver wei ght was seen to increase from July to August/Septem ber, most probably as a result of accumulation of metabolites, especia lly fat and glycogen. Furthermore, the concentratio ns of the metals found in the liver of the frog were in the order: Cu>Cr>C d>Pb>Ni. On the other hand, the concentrations of t he metals found in the water were in the order: Cu>Pb>Cd> Ni >Cr.
Some reproduction characteristics of the Caspian Vimba, Vimba vimba persa, were studied from Oct.... more Some reproduction characteristics of the Caspian Vimba, Vimba vimba persa, were studied from Oct. 2008 to Sep. 2009 in coastal waters of the Caspian Sea (Mazandaran province). 994 specimens were monthly collected from 6 fish landing sites of Ramsar, Tonekabon, Chalus, Mahmood Abad, Sari and Behshahr. The fecundity was measured using 92 specimens. This species was found to have more abundance in spring (especially April and May). The samples composed of 397(42.6%) male, 537(57.4%) female; the sex ratio was M: F = 1:1.35. The advanced stages of maturity (4th & 5th) were found in April and May. The highest Gonadosomatic Index in females was in May and the lowest one was in July. The average of absolute and relative fecundities was 17198±7710 and 171.85±48.8, respectively.
IOP Conference Series: Earth and Environmental Science, 2021
The Caspian Sea, which is known as the largest lake in the world, is located in the northern part... more The Caspian Sea, which is known as the largest lake in the world, is located in the northern part of Iran. Caspian Sea Sprat or Clupeidae are pelagic fish and play an important role in the food chain. In Iran, clupeid fish are caught by a conical lift net with artificial light and at night. The color of artificial light used in the conical lift net is white or sunny. In a study conducted from May 2018 to January 2019 in the fishing port of Amirabad, the effect of two types of artificial light (blue and red light) was investigated. For this purpose, two lamps with a color of blue and red with the same Volt and Ampere of white light were used in the depth of 40 – 50 meters. The results show a significant difference in the average length of sprat fish caught in each of the lights used (p <0.05). In blue light, the fish caught had a longer length and a heavier weight, while the fish caught in red light had a shorter length and a lighter weight.
One of the major sources of impacts on marine resources comes from climate variability and regime... more One of the major sources of impacts on marine resources comes from climate variability and regime shifts. In this context, the present study pinpoints the role of climatic and environmental parameters on the dynamic of kilka in the Caspian Sea. During the last decades, landings and stocks of the main pelagic species of kilka had been changed dramatically in the Caspian Sea. This study focuses on the last three decades of the climate regime and tries to explain the part of the changes in the recruitment (R) and spawning stock biomass (SSB) of three kilka species. Based on the statistical analysis of data series, it is found that regime changes in the global and regional environmental variables started in the mid-1995s, however, the shift of the late 1990s (1998) was more strong in the Caspian Sea. The study further reveals that the global climatic indices changes in the late 1990s are triggering the regional and local indices induced regime shifts in the late 1990s and 2000s. The stu...
This study aimed to investigate the impact of fishing in Iranian part of the Caspian Sea during 1... more This study aimed to investigate the impact of fishing in Iranian part of the Caspian Sea during 1991-2017 years using fishing-in-balance (FiB), mean trophic level (MTI), ratio of pelagic and demersal fish landings (P/D) and piscivory (PI) indices. The mean (±S.D) of MTI were 2.91±0.38 (95% C.I =3.14-2.67). Its value is first reduced and then increase happened and ultimately stays constant. The mean of FiB was 0.13 (95% C.I=0.28-(-0.02)) and its trend was similar to that of total landing. The mean of Pi index, P/D index, pelagic fish and demersal fish were 0.04±0.02 (95% C.I=0.09-(-0.012)), 3.16±2.31 (95% C.I = 0.6-(-0.52)), 38529±22883 (95% C.I=38585-38472) and 13380±3314 (95% C.I= 3401-13358), respectively. The results revealed that the fish stock in the Iranian waters of the Caspian Sea have been over-exploited. Considering that fishing impacts on the trophic level, we suggest that the fishery management should not continue this trend.
Measurements of bioavailability responses in frogs from contaminated sites could provide valuable... more Measurements of bioavailability responses in frogs from contaminated sites could provide valuable data for environmental risk assessment. Biomarkers are sensitive to both e nvironmental pollution and confounding factors that are not related to pollution. The specimens were collected on a monthl y basis from the Babol-River from July to September 2010 to determine if monthly changes exist in condition, he patosomatic index (HSI) and frogs. Fulton condition factor (FCF range: 1.513±0.431 ‐ 1.638±0.473), hepatosomatic index ( HSI range: 3.901±0.504-5.231±1.206), Bioaccumulation factor (BAF), the highest level of copper was observed. Liver wei ght was seen to increase from July to August/Septem ber, most probably as a result of accumulation of metabolites, especia lly fat and glycogen. Furthermore, the concentratio ns of the metals found in the liver of the frog were in the order: Cu>Cr>C d>Pb>Ni. On the other hand, the concentrations of t he metals found in the water were in the order: Cu>Pb>Cd> Ni >Cr.
Some reproduction characteristics of the Caspian Vimba, Vimba vimba persa, were studied from Oct.... more Some reproduction characteristics of the Caspian Vimba, Vimba vimba persa, were studied from Oct. 2008 to Sep. 2009 in coastal waters of the Caspian Sea (Mazandaran province). 994 specimens were monthly collected from 6 fish landing sites of Ramsar, Tonekabon, Chalus, Mahmood Abad, Sari and Behshahr. The fecundity was measured using 92 specimens. This species was found to have more abundance in spring (especially April and May). The samples composed of 397(42.6%) male, 537(57.4%) female; the sex ratio was M: F = 1:1.35. The advanced stages of maturity (4th & 5th) were found in April and May. The highest Gonadosomatic Index in females was in May and the lowest one was in July. The average of absolute and relative fecundities was 17198±7710 and 171.85±48.8, respectively.
IOP Conference Series: Earth and Environmental Science, 2021
The Caspian Sea, which is known as the largest lake in the world, is located in the northern part... more The Caspian Sea, which is known as the largest lake in the world, is located in the northern part of Iran. Caspian Sea Sprat or Clupeidae are pelagic fish and play an important role in the food chain. In Iran, clupeid fish are caught by a conical lift net with artificial light and at night. The color of artificial light used in the conical lift net is white or sunny. In a study conducted from May 2018 to January 2019 in the fishing port of Amirabad, the effect of two types of artificial light (blue and red light) was investigated. For this purpose, two lamps with a color of blue and red with the same Volt and Ampere of white light were used in the depth of 40 – 50 meters. The results show a significant difference in the average length of sprat fish caught in each of the lights used (p <0.05). In blue light, the fish caught had a longer length and a heavier weight, while the fish caught in red light had a shorter length and a lighter weight.
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