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  • 1
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    Releasing of Sturgeon Fingerlings from Shahid Beheshti rearing and propagation center and Yousefpour Hatchery in 1999 (2018)
    Details
    Publication Date: 2021-05-19
    Description: During 1999, Shahid Beheshti & Yousefpour hatcheries were released 6499769 fingerlings produced by 225 female spawners from 1999.5.28 to 1999.7.26. Totally 2458667 fingerlings released from Shahid Beheshti hatchery which consisted of 2360490 specimen of Acipenser persicus (96% frequency) with mean weight of 1.8 g and 7.6 cm length, 86177 specimen of Acipenser stellatus (3.5% frequency) with mean weight of 3.9 g and 11.2 cm length, 1200 specimen of Acipenser nudiventris (0.5% frequency) with mean weight of 3.6 g and 8.7cm length. Out of the total numbers of fingerlings released 82.4% of A. persicus, 45% of A. stellatus & 25% of A. nudiventris fingerlings were below 3g. The survival rate of A. persicus & A. stellatus were 33.7% and 32.0%, respectively. The result of study on growth coefficient and condition factor showed these fingerlings had low growth coefficient (4.89) and mean condition factor (04). In Yousefpour hatchery 4020002 sturgeon fingerlings were released consist of 3968262 specimen of A. persicus (99.4% frequency) with mean weight of 3.1 g and 8.9cm length, 51740 specimen of A. stellatus (0.6% frequency) with mean weight of 0.9g & 6.3cm length. Out of total number of released 61.7% of A. persicus and 100% Of A. stellatus were below 3g. The total Survival rate of A. persicus & A. Stellatus fingerlings were 46.3 and 28.4%, respectively. The experiments Showed that the growth coefficient and condition factor were low, 3.64 and 0.37, respectively. The results of comparing the mean quality of A. persicus between Shahid beheshti & Yousefpour (P0.05) showed that there is a significant difference among length, weight, condition factor & growth coefficient of these 2 hatcheries in a way that the fingerlings released from Yousefpour rearing and propagation center had better condition in terms of length and weight but, their growth coefficient and Condition factor were lower than A. persicus fingerlings in Shahid Beheshti hatchery.
    Description: Published
    Keywords: Sturgeon ; Fingerlings ; Rearing ; Hatchery ; Spawner ; Acipenser persicus ; A. stellatus ; A. nudiventris ; Specimen ; Acipenser stellatus ; Acipenser nudiventris ; A. persicus ; Weight ; Length ; Survival rate
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.149-158
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  • 2
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    Determination of appropriate time for sturgeon catch (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: Practical phase of the project aimed at studying and determination of the most appropriate time for sturgeon catch was conducted at 10 catch stations (2 in each region) in Guilan, Mazandaran and Golestan provinces in 2002 and 2003. Number of catch stations was 4 in Guilan and Mazandaran provinces each and 2 in Golestan province. The project was carried out following the ratifications of the high committee for sustainable utilization of sturgeons which passed through in 2001. Considering the results on factors like average caviar yield, quantity and quality of produced caviar, sex composition of caught spawners and catch per unit effort we found that the average caviar yield of Persian sturgeon in all three Guilan, Mazandaran and Golestan provinces was higher in spring catch than autumn and winter and in winter catch was higher than autumn while the amount of caviar obtained was higher in autumn. Considering sex composition percentage of mature female caught was higher in spring than other seasons. Catch stations located in Guilan and western and central Mazandaran showed almost similar condition. Spring catch from late march (last 10 days) up to the 10th of May, autumn catch from late September and early October (23 September- 2 October) to the 1 st December, and winter catch from 1 st to 21st march are suitable period for catch. At the Khazarabad catch station the suitable time of catch differs from other stations therefore the proper time for catch appears to be 10- 20 may in spring and 21- 30 January in winter catch seasons. The quality and quantity of catch is suitable in spring from 21- 31 march to 21- 31 may, in autumn catch from 12- 22 October to 11- 21 December and in winter catch from 9- 19 February to 11- 20 march at catch stations located in Golestan province. As for stellate sturgeon at catch stations of Guilan and Mazandaran provinces the spring catch from 21 march specially from 21 April to 20 June was suitable and all other quantitative and qualitative factors confirmed better quality and quantity of catch in this period (21 April- 20 June) in comparison to other seasons. Gill nets (lower in number as compared to other sturgeons) could be set up beginning from 20 February to 20 March in winter catch. Our study showed quantitative and qualitative increase in catch from 9- 19 April to the end of decade from 22-31 May suggesting a suitable time of catch for stellate sturgeon in Golestan province. Based on our quantitative and qualitative results the summer catch is not suitable for Persian sturgeon and stellate sturgeon and winter catch for stellate sturgeon.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Sturgeon fishes ; Persian sturgeon ; Stellate sturgeon ; Time of catch ; Sex composition ; Determination
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 112pp.
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  • 3
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    Determining the suitable mesh size for capturing Persian sturgeon (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: The present study was carried out at the Turkman catch station of Golestan province in March and May 2002 to examine suitable mesh size of gill nets used for Persian sturgeon catch in order to decrease possibility of immature Persian sturgeon and increase likelihood of catch of large sized specimens. The Holt model (1963) was used to determine suitable length for catch and also selection of mature Persian sturgeon females. Following preliminary studies some 920 experimental gill net (mesh size 170mm from knot to the next) similar to those generally used by Iranian fisheries except for mesh size (150 mm) were set up in the Caspian Sea. During two months experimental period some 128 and 110 sturgeon fish were caught in witness and experimental nets respectively. Out of those fishes caught by witness nets 63 specimens were Persian sturgeon (49.2%), 57 were stellate sturgeon (44.5%) while in the experimental nets 95 specimens (86.4%) were Persian sturgeon and 7 specimens (6.4%) were stellate sturgeon. Considering maturity status of fishes 42 Persian sturgeon caught by witness net were mature females while this figure was 83 (87.4%) in experimental nets. Mean fork length of Persian sturgeon was 152.9± 13.8cm and 162.4± 13.6cm in witness and experimental nets respectively. The optimum calculated fork length to begin catch of female Persian sturgeon in witness net was 132.5cm and in experimental net 150.2 cm. The calculated selection factor was 0.9. Considering the reported mean fork length of Persian sturgeon females in statistical and biological study of sturgeons the mesh size of 162mm is recommended as suitable mesh size for this species. The amount of caviar and mean caviar yield of Persian sturgeon in witness net was 26.7 and 6.4 ±1.7 kg and in experimental nets 610.6 and 7.4± 1.9kg. One way ANOVA and Tukey s test showed that there are significant differences between factors like age, mean caviar yield and fork length of Persian sturgeon caught by witness and experimental nets at 95% confidence level. The results obtained in this study shows that increasing mesh size of gill nets used for Persian sturgeon catch to 170mm may guarantee objectives of stock managements including decrease in catch of immature and increase in mature and larger sturgeon catches to secure optimum and sustainable stock deployment.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Mesh size ; Persian sturgeon ; Suitable length for catch ; Selection factor ; Holt- stocks
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 36pp.
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  • 4
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    Stock assessment of Sturgeon fishes in the southern part of Caspian Sea (Iranian water) (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: The marine survey for sturgeon stock assessment was conducted in summer, winter and spring in the years 2006 and 2009 to estimate the relative and absolute abundance and percentage composition of each species in the Guilan, Mazandaran and Golestan Provinces. This survey was carried out in the Iranian waters of the Caspian Sea on board the Sisara2 and Guilan vessels using trawl nets at 2-100 m depths. Trawling was carried out in 85 stations that were selected using a stratified random design. The number of stations in each scope was based on the area of the scope in terms of the total area. Trawling and sampling in shallow water up to 10 m were carried out using 9 m trawl nets whereas 24.7 m trawl nets were used for depths more than 10 m. Trawl surveys were carried out in the daytime. Trawling velocity was kept at 2.5-3 kts and trawls lasted half an hour in order to calculate abundance, and biomass of sturgeons using the swept area method. Catch per unit area (CPUA) in the winter 2006 survey was 3853 specimens nm2 , in the summer and winter 2007 survey was 1854 , 2912 specimens nm2 at depths less than 10 m respectively . CPUA for sturgeons in spring 2008 survey was 2103 specimens nm2 at depths less than 10 m and 393 specimens nm2 at depths greater than 10 m (10-100 m depth). These values in the winter 2008 survey dropped to 44 specimens nm2 at depths at depths above 10 m. CPUA for sturgeons in the spring 2009 survey was 300 specimens nm2 at depths less than 10 m and 307 specimens nm2 at depths greater than 10 m. In all the surveys conducted CPUA for A. persicus was higher than that for the other sturgeon species. Based on the calculations carried out in the marine survey in winter 2006 the estimated absolute abundance for sturgeons was about 2977.363 thousand. The total biomass of sturgeon was estimated as 131.713 tons. In the summer 2007 survey total abundance was estimated 1432.398 thousand, and total biomass of sturgeons was estimated at about 312.161 tons. In the winter 2007 survey total abundance for sturgeons was estimated at about 2250.105 thousand, and total biomass was estimated 578.08 tons. In the spring 2008 survey total abundance was estimated at about 3002.832 thousand. The total biomass was estimated at about 2533.318 tons .In the winter 2008 survey total abundance was estimated at about 152.722 thousand, and total biomass in winter 2008 was estimated 170.540 tons. Total abundance in spring 2009 survey was 1310.232 thousand and total biomass was estimated at 2019.tons. Investigation of stomach content of sturgeon Acipenser persicus caught under 10m depth in 2006 to 2007 surveys showed that there is significant difference in the consumed food. Polychaeta is the major food consumed and crustacean an the minor one(P〉0.05).Also no new types of food( such as bony fishes or benthic) have been observed in food chain of Acipenser persicus only the food consumption rate has been related to the season of year and increases or decreases in warm or cold seasons, respectively For physiological study and determination of sexual maturation stages in sturgeon,119 gonad sampling prepared. The results showed that 63 % of fishes were females and 37 % of them were males. Gill microscopic study shows complications such as hyperplasia, curvature, adhesion, embowed, shorting and lengthen of secondary filaments and fraught bloody. Microscopic study on liver indicates signs of cloudy inflammation, fatty degeneration, dispersion of billed secretions and cell atrophy. The population genetic structure of Persian sturgeon (Acipenser persicus) in Sefidrood and Gorganrood rivers watershed analyzed based on microsatellite markers during sturgeons assessment in 2006-2008. Results showed that Acipenser persicus in two region of south part of Caspian Sea are two independent populations.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Stock assessment ; Sturgeon ; Acipenser persicus ; Diet ; Gills ; Sex ; Microsatellite ; Population ; Genetic ; Survey ; Species ; Sampling ; Trawling ; CPUA ; A. persicus ; Biomass ; Polychaeta ; Maturation
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 154pp.
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  • 5
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    Variations in sturgeon populations in the coastal waters of the Caspian Sea (Guilan province) (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: The present study was conducted from autumn 2003 to summer 2005 with the objective to estimate distribution and relative abundance in different species of sturgeons as a function of seasons, and regions in the west coast of the Caspian Sea (Guilan province).Gillnets with a different mesh sizes (26, 33, 40, 60, 100, and 150 mm) were set up at different depths(2, 5, and 10 m) for 24 h. Data on variations in catch, catch per unit effort(CPUE) and length and age composition of sturgeon species were analyzed statistically. Data on CPUE in each region and depth and mean estimates of length and age in fish were reported for each season and each year of the study period. CPUE during 2004-2005 was 1.32 fish which was 30.1% lower than CPUE (1.89 fish) recorded in 2003-2004.CPUE for all species except A. nudiventris decreased during 2004-2005 as compared to that in 2003-2004. Acipenser persicus caught during 2003-2004 and 2004-2005 ranged from 15 to 45 cm in length and comprised 91.1 and 97.1% respectively of the total sturgeon catch. These fish belonged to the one year age class. Mean length recorded in sturgeon fish caught in 2004-2005 decreased as compared to that recorded in 2003-2004. Significant differences were recorded in total length of fish caught in 2003-2004 and 2004-2005. Results obtained from the present study reveal that the abundance of fish increased from west to east indicating a direct relationship between the general currents found in the Caspian Sea and the higher density of nutrients in the eastern region.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Stock ; Sturgeons ; Gillnets ; CPUE ; Fish ; Species ; A. nudiventris ; Acipenser persicus ; Length ; Nutrients ; Costal waters
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 59pp.
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  • 6
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    Marking Persian sturgeon (Acipenser persicus) using new method and tracking them under 10 m depth in the sea (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: The second phase of the project entitled Marking Persian sturgeon (Acipenser persicus) using new method and tracking them under 10 m depth in the sea was approved in 2004. This project which terminated in April 2009 was carried out during 2004 to 2008 to track coded wire tagged (CWT) sturgeons under 10 m depth. Among the specimens caught, three were juvenile Persian sturgeon tagged in the first phase (2003) were caught in the second phase (2004). The data related to tagging & capture of sturgeon from 2003 to 2008 is included. Totally, 426325 specimens of Persian sturgeon were tagged in 3 weight classes (〉3g, 3 to 5g and 6 to 10g). Among the population studied, 101500 of them belonged to specimens of 2003 which were tagged by three hatcheries; Shahid Beheshti, Shahid Rajaee & Shahid Marjani and then released into the rivers (Sefidrud, Tajan & Gorganrud) entering the Caspian Sea. During 2004 to 2008, 324825 specimens were tagged in Shahid Beheshti hatchery and released into the Sefidrud River. Gill net were used to catch the tagged Persian sturgeon specimens under 10m depth. During 2003 to 2008, 3616 Persian sturgeon were captured of which 43 juveniles bore CWT. Among the captured CWT sturgeons, 23 specimens belonged to the 6-10 g weight class, 19 specimens belonged to the 3 to 5g weight class and one sturgeon was 〉3g. Based on the results, it can be concluded that higher weight at releasing time can lead to higher survival rate and fisheries returns. Some other factors that influence catch rate of CWT sturgeons are as follows: Catch station (highest catch rates in Persian sturgeon juveniles belonged to Chaboksar station), catch season (highest catch rates were recorded in summer which can be attributed to the release of juveniles), catch depth (in winter highest catch occurred at 5 to 10m depth, in other seasons highest catch number was recorded at 3 to 5m depth. Decrease in water temperature is the reason for higher catch numbers at 5 to 10m depth in winter. Also, mesh size can effect on catch rate (highest catch rate belongs to nets with 22mm mesh size). Statistical analysis of results showed significant difference (p〈0.05) among the various groups studied. Existence of illegal catch nets in the river can also cause mortality of the released juveniles.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Tagging ; CWT ; Persian sturgeon ; Juvenile ; Releasing ; Acipenser persicus ; Specimens ; Population ; Mortality
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 76pp.
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  • 7
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    Releasing of sturgeon fingerlings from Shahid Beheshti rearing and propagation center and Yousefpour hatchery in 1999 (2021)
    In:  http://aquaticcommons.org/id/eprint/24131 | 18721 | 2018-08-03 08:04:27 | 24131 | Iranian Fisheries Science Research Institute
    Details
    Publication Date: 2021-07-15
    Description: During 1999, Shahid Beheshti & Yousefpour hatcheries were released 6499769 fingerlings produced by 225 female spawners from 1999.5.28 to 1999.7.26. Totally 2458667 fingerlings released from Shahid Beheshti hatchery which consisted of 2360490 specimen of Acipenser persicus (96% frequency) with mean weight of 1.8 g and 7.6 cm length, 86177 specimen of Acipenser stellatus (3.5% frequency) with mean weight of 3.9 g and 11.2 cm length, 1200 specimen of Acipenser nudiventris (0.5% frequency) with mean weight of 3.6 g and 8.7cm length. Out of the total numbers of fingerlings released 82.4% of A. persicus, 45% of A. stellatus & 25% of A. nudiventris fingerlings were below 3g. The survival rate of A. persicus & A. stellatus were 33.7% and 32.0%, respectively. The result of study on growth coefficient and condition factor showed these fingerlings had low growth coefficient (4.89) and mean condition factor (04). In Yousefpour hatchery 4020002 sturgeon fingerlings were released consist of 3968262 specimen of A. persicus (99.4% frequency) with mean weight of 3.1 g and 8.9cm length, 51740 specimen of A. stellatus (0.6% frequency) with mean weight of 0.9g & 6.3cm length. Out of total number of released 61.7% of A. persicus and 100% Of A. stellatus were below 3g. The total Survival rate of A. persicus & A. Stellatus fingerlings were 46.3 and 28.4%, respectively. The experiments Showed that the growth coefficient and condition factor were low, 3.64 and 0.37, respectively. The results of comparing the mean quality of A. persicus between Shahid beheshti & Yousefpour (P0.05) showed that there is a significant difference among length, weight, condition factor & growth coefficient of these 2 hatcheries in a way that the fingerlings released from Yousefpour rearing and propagation center had better condition in terms of length and weight but, their growth coefficient and Condition factor were lower than A. persicus fingerlings in Shahid Beheshti hatchery.
    Keywords: Aquaculture ; Acipenser persicus ; A. stellatus ; A. nudiventris ; Rearing ; Fingerlings ; Spawner ; Iran
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 149-158
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  • 8
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    Stock assessment of sturgeon fishes in the southern part of Caspian Sea (Iranian water) (2021)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25298 | 18721 | 2018-09-07 08:30:09 | 25298 | Iranian Fisheries Science Research Institute
    Details
    Publication Date: 2021-07-16
    Description: The marine survey for sturgeon stock assessment was conducted in summer, winter and spring in the years 2006 and 2009 to estimate the relative and absolute abundance and percentage composition of each species in the Guilan, Mazandaran and Golestan Provinces. This survey was carried out in the Iranian waters of the Caspian Sea on board the Sisara2 and Guilan vessels using trawl nets at 2-100 m depths. Trawling was carried out in 85 stations that were selected using a stratified random design. The number of stations in each scope was based on the area of the scope in terms of the total area. Trawling and sampling in shallow water up to 10 m were carried out using 9 m trawl nets whereas 24.7 m trawl nets were used for depths more than 10 m. Trawl surveys were carried out in the daytime. Trawling velocity was kept at 2.5-3 kts and trawls lasted half an hour in order to calculate abundance, and biomass of sturgeons using the swept area method. Catch per unit area (CPUA) in the winter 2006 survey was 3853 specimens nm^2 , in the summer and winter 2007 survey was 1854 , 2912 specimens nm^2 at depths less than 10 m respectively . CPUA for sturgeons in spring 2008 survey was 2103 specimens nm2 at depths less than 10 m and 393 specimens nm2 at depths greater than 10 m (10-100 m depth). These values in the winter 2008 survey dropped to 44 specimens nm^2 at depths at depths above 10 m. CPUA for sturgeons in the spring 2009 survey was 300 specimens nm^2 at depths less than 10 m and 307 specimens nm^2 at depths greater than 10 m. In all the surveys conducted CPUA for A. persicus was higher than that for the other sturgeon species. Based on the calculations carried out in the marine survey in winter 2006 the estimated absolute abundance for sturgeons was about 2977.363 thousand. The total biomass of sturgeon was estimated as 131.713 tons. In the summer 2007 survey total abundance was estimated 1432.398 thousand, and total biomass of sturgeons was estimated at about 312.161 tons. In the winter 2007 survey total abundance for sturgeons was estimated at about 2250.105 thousand, and total biomass was estimated 578.08 tons. In the spring 2008 survey total abundance was estimated at about 3002.832 thousand. The total biomass was estimated at about 2533.318 tons .In the winter 2008 survey total abundance was estimated at about 152.722 thousand, and total biomass in winter 2008 was estimated 170.540 tons. Total abundance in spring 2009 survey was 1310.232 thousand and total biomass was estimated at 2019.tons. Investigation of stomach content of sturgeon Acipenser persicus caught under 10m depth in 2006 to 2007 surveys showed that there is significant difference in the consumed food. Polychaeta is the major food consumed and crustacean an the minor one(P〉0.05).Also no new types of food( such as bony fishes or benthic) have been observed in food chain of Acipenser persicus only the food consumption rate has been related to the season of year and increases or decreases in warm or cold seasons, respectively For physiological study and determination of sexual maturation stages in sturgeon,119 gonad sampling prepared. The results showed that 63 % of fishes were females and 37 % of them were males. Gill microscopic study shows complications such as hyperplasia, curvature, adhesion, embowed, shorting and lengthen of secondary filaments and fraught bloody. Microscopic study on liver indicates signs of cloudy inflammation, fatty degeneration, dispersion of billed secretions and cell atrophy. The population genetic structure of Persian sturgeon (Acipenser persicus) in Sefidrood and Gorganrood rivers watershed analyzed based on microsatellite markers during sturgeons assessment in 2006-2008. Results showed that Acipenser persicus in two region of south part of Caspian Sea are two independent populations.
    Keywords: Fisheries ; Iran ; Caspian Sea ; Mazandaran Province ; Golestan Province ; Guilan Province ; Sefidrood River ; Gorganrood River ; Stock assessment ; Sturgeon ; Acipenser persicus ; Diet ; Gills ; Sex ; Microsatellite ; Population ; Genetic ; Survey ; Species ; Sampling ; Trawling ; CPUA ; A. persicus ; Biomass ; Polychaeta ; Maturation
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 154
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  • 9
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    Marking Persian sturgeon (Acipenser persicus) using new method and tracking them under 10 m depth in the sea (2021)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25240 | 18721 | 2018-09-06 06:10:05 | 25240 | Iranian Fisheries Science Research Institute
    Details
    Publication Date: 2021-07-16
    Description: The second phase of the project entitled Marking Persian sturgeon (Acipenser persicus) using new method and tracking them under 10 m depth in the sea was approved in 2004. This project which terminated in April 2009 was carried out during 2004 to 2008 to track coded wire tagged (CWT) sturgeons under 10 m depth. Among the specimens caught, three were juvenile Persian sturgeon tagged in the first phase (2003) were caught in the second phase (2004). The data related to tagging & capture of sturgeon from 2003 to 2008 is included. Totally, 426325 specimens of Persian sturgeon were tagged in 3 weight classes (〉3g, 3 to 5g and 6 to 10g). Among the population studied, 101500 of them belonged to specimens of 2003 which were tagged by three hatcheries; Shahid Beheshti, Shahid Rajaee & Shahid Marjani and then released into the rivers (Sefidrud, Tajan & Gorganrud) entering the Caspian Sea. During 2004 to 2008, 324825 specimens were tagged in Shahid Beheshti hatchery and released into the Sefidrud River. Gill net were used to catch the tagged Persian sturgeon specimens under 10m depth. During 2003 to 2008, 3616 Persian sturgeon were captured of which 43 juveniles bore CWT. Among the captured CWT sturgeons, 23 specimens belonged to the 6-10 g weight class, 19 specimens belonged to the 3 to 5g weight class and one sturgeon was 〉3g. Based on the results, it can be concluded that higher weight at releasing time can lead to higher survival rate and fisheries returns. Some other factors that influence catch rate of CWT sturgeons are as follows: Catch station (highest catch rates in Persian sturgeon juveniles belonged to Chaboksar station), catch season (highest catch rates were recorded in summer which can be attributed to the release of juveniles), catch depth (in winter highest catch occurred at 5 to 10m depth, in other seasons highest catch number was recorded at 3 to 5m depth. Decrease in water temperature is the reason for higher catch numbers at 5 to 10m depth in winter. Also, mesh size can effect on catch rate (highest catch rate belongs to nets with 22mm mesh size). Statistical analysis of results showed significant difference (p〈0.05) among the various groups studied. Existence of illegal catch nets in the river can also cause mortality of the released juveniles.
    Keywords: Biology ; Ecology ; Iran ; Caspian Sea ; SefidRud River ; Tajan River ; Gorganrud River ; Tagging ; CWT ; Persian sturgeon ; Juvenile ; Releasing ; Acipenser persicus ; Specimens ; Population ; Mortality
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 76
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  • 10
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    Variations in sturgeon populations in the coastal waters of the Caspian Sea (Guilan province) (2021)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    In:  http://aquaticcommons.org/id/eprint/25106 | 18721 | 2018-08-23 05:36:01 | 25106 | Iranian Fisheries Science Research Institute
    Details
    Publication Date: 2021-07-16
    Description: The present study was conducted from autumn 2003 to summer 2005 with the objective to estimate distribution and relative abundance in different species of sturgeons as a function of seasons, and regions in the west coast of the Caspian Sea (Guilan province).Gillnets with a different mesh sizes (26, 33, 40, 60, 100, and 150 mm) were set up at different depths(2, 5, and 10 m) for 24 h. Data on variations in catch, catch per unit effort(CPUE) and length and age composition of sturgeon species were analyzed statistically. Data on CPUE in each region and depth and mean estimates of length and age in fish were reported for each season and each year of the study period. CPUE during 2004-2005 was 1.32 fish which was 30.1% lower than CPUE (1.89 fish) recorded in 2003-2004.CPUE for all species except A. nudiventris decreased during 2004-2005 as compared to that in 2003-2004. Acipenser persicus caught during 2003-2004 and 2004-2005 ranged from 15 to 45 cm in length and comprised 91.1 and 97.1% respectively of the total sturgeon catch. These fish belonged to the one year age class. Mean length recorded in sturgeon fish caught in 2004-2005 decreased as compared to that recorded in 2003-2004. Significant differences were recorded in total length of fish caught in 2003-2004 and 2004-2005. Results obtained from the present study reveal that the abundance of fish increased from west to east indicating a direct relationship between the general currents found in the Caspian Sea and the higher density of nutrients in the eastern region.
    Keywords: Fisheries ; Iran ; Caspian Sea ; Guilan Province ; Stock ; Sturgeons ; Gillnets ; CPUE ; Fish ; Species ; A. nudiventris ; Acipenser persicus ; Length ; Nutrients ; Costal waters
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 59
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