علوم زیستی دریا
Emad Koochaknejad; Ahamd Savari; Alireza Safahieh; Gholamreza Eskandari
Abstract
In this study age, growth and maturity of Hilsa shad in Khuzestan province were analyzed. 394 number of fishes from marine habitat (Life-Boseif), estuaries (Bahmanshir and Arvand) and rivers (Bahmanshir and Karoon) from February 2014 to September 2014 were collected using commercial fishing with gill ...
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In this study age, growth and maturity of Hilsa shad in Khuzestan province were analyzed. 394 number of fishes from marine habitat (Life-Boseif), estuaries (Bahmanshir and Arvand) and rivers (Bahmanshir and Karoon) from February 2014 to September 2014 were collected using commercial fishing with gill net. Total length and wet weight of each fish were measured with precision of 1 cm and 1 gram. Sagittal otoliths were extracted for age determination of the fish. Then abdominal cavity of each sample were opened for determining sex and maturity stage. Growth parameters were calculated using von Bertalanffy growth function (L∞=58.365, K=0.26, t0=-0.16). Phi-prime constant was obtained 2.95. Length and age at first maturity were obtained 27.32cm and 2.4 g respectively using logistic model to fit a and b parameters with observed data in spawning season.
علوم زیستی دریا
shafa hoveizavi; Babak Doustshenas; Gholamreza Eskandari; Ahmad Savari; Hossein Mohammadasgari
Abstract
The main purpose of this study was to describe and estimate the seasonal pattern of discard fish in the waters of the Persian Gulf coasts in Khuzestan. sampling was carried out Monthly by using fishing boats in the waters of Khuzestan province for one year in fishing areas of Lifeh, Boseif, Khure-mussa ...
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The main purpose of this study was to describe and estimate the seasonal pattern of discard fish in the waters of the Persian Gulf coasts in Khuzestan. sampling was carried out Monthly by using fishing boats in the waters of Khuzestan province for one year in fishing areas of Lifeh, Boseif, Khure-mussa and Bahrakan.Discard fish samples were included 61 species from 37 families, nearly 39 percent commercial and 61 percent of non- commercial species. Rayfish and catfish have been observed in most fishing nets. Average size of most species particularly bony fish were under 15 cm. The amount of discard fish per unit of fishing effort is not significantly different between seasons. The highest portion of the catch belongs to Rayfishes. Total discard fishes of gillnets were estimated 3162 tones. Total weight of commercial fishes with small size in trash fish was estimated 225 tones. The rate and proportion of discard fish in total catch of gillnet was estimated 0.23 and 0.31 respectively. Chondrichthyes with 12 species and 60% of gillnet catch has the highest percentage of discard fish of gillnet. A large number of commercial species with small size such as Otolithes ruber (Schneider, 1801), ( Scomberomorus commerson (Lacepede, 1801) and Scomberoides commersonnianus(Lacepede, 1801) could be due to the role of nursery grounds in Khuzestan coastal waters.
علوم زیستی دریا
gh s; Emad Koochaknejad; Yosef Mayahi; Houshang Ansari
Abstract
The main goal of this study was estimating discards of trawl nets in north western part of the Persian Gulf. Data were collected from fishing boats in fishing areas of Lifeh, Boseif, Khure-mussa and Bahrakan from October 2011 to September 2012 with collaboration of fishery office. Discard samples include ...
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The main goal of this study was estimating discards of trawl nets in north western part of the Persian Gulf. Data were collected from fishing boats in fishing areas of Lifeh, Boseif, Khure-mussa and Bahrakan from October 2011 to September 2012 with collaboration of fishery office. Discard samples include 101 species from 61 families which are 39.5% of commercial catch and 60.4% of non-commercial catches. Rayfish and catfish have been observed in most fishing nets. The average size of bony fishes in discard samples was lower than 15 cm. Total weights of discards was estimated about 1109 tons per year. Total weight of commercial fishes with small size in discards was estimated 2736 tones. The rate and proportion of discards in total catch of trawl was estimated 0.5 and 1.03 respectively. Osteichthyes with 70 species and 50.7% of trawl catch has the highest percentage of discards in trawl nets. High rate of small fishes in commercially important species of discards is probably due to nursery role of Khuzestan coastal waters.
علوم زیستی دریا
Gholamreza Eskandari; Ahmad Savari; Perita Kochanian; Aseiied aminollah Taghavi Motlagh
Volume 11, Issue 1 , November 2012, , Pages 49-57
Abstract
In the present study, length structure, mortality and exploitation rate of Otolithes ruber during a ten-year period were studied. Sampling was carried out by using bottom trawl net in the fishing area in Northwest of Persian Gulf over 1 year study period. Length data was also collected from fisheries ...
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In the present study, length structure, mortality and exploitation rate of Otolithes ruber during a ten-year period were studied. Sampling was carried out by using bottom trawl net in the fishing area in Northwest of Persian Gulf over 1 year study period. Length data was also collected from fisheries research institute and fishery organization. Age determination was done by reading annual rings on sectioned otolith. Growth parameters were calculated based on age and length data. These data were used to estimate natural mortality rate. Total mortality was obtained from the age curve. Logarithmic catch and natural mortality were calculated from Pauly's equation. The averages of length in the last ten years were 35 to 39 cm. The samples ranged in length from 12 to 58 cm with the maximum frequencies between 28-44 cm. Length distribution was normal in this study. The maximum catch was composed of fish in the 40 to 48 cm length range with an average age of 2 to 3 years. The average total mortality, natural mortality and fishing mortality were 0.98, 0.56, and 0.42 respectively. Mortality was higher in age group 0 and age group 1, but mortality of the other age groups dramatically decreased. Exploitation rate in the last ten years were 0.42 indicating a near complete exploitation. Based on the results a more effective exploitation strategy is suggested in this region.