علوم زیستی دریا
Ali Sadough Niri; Ehsan Kamrani; Iman Sourinejad
Abstract
The present study was conducted to investigate length selectivity and determine optimal meshsize for fishery of Longtail Tuna (Thunnus tonggol) surface drift gillnets in northeast of Oman Sea and fishing grounds of Chabahar, Konarak and Ramin (Sistan and Baluchistan Province) from October 2016 to June ...
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The present study was conducted to investigate length selectivity and determine optimal meshsize for fishery of Longtail Tuna (Thunnus tonggol) surface drift gillnets in northeast of Oman Sea and fishing grounds of Chabahar, Konarak and Ramin (Sistan and Baluchistan Province) from October 2016 to June 2017. Fishing gear was included Longtail Tuna surface drift gillnets with 100, 110, 130 and 165 mm stretched mesh size. During 45 stages of navigation with fiberglass boats and wooden vessel, 477 fish specimen were caught, which recorded length frequency data, total weight, and operculum and body girth. A total of 228 samples were Dissected and their ovarian maturation stages were determined to estimate the length of sexual maturity (Lm50). The minimum, maximum and mean (± standard deviation) fork length of the samples were 32, 90 and 55.1±13.35 cm, respectively. Operculum girth-fork length and maximum girth-length relationship were obtained as: Gop = 0.5379 FL+0.4955 and Gmax = 0.5879 FL+ 0.5095, respectively. Size at first maturity (Lm50) of Longtail Tuna was obtained 53.7 cm FL. Using Sechin selectivity method, optimal catch size of 100, 110, 130 and 165 mm gillnet mesh sizes were determined as: 35, 38, 46 and 57 cm, respectively. Using selection coefficient and Lm50, standard mesh size for fishing Longtail Tuna were determined 170 mm. Due to the fact that immature fish are not caught by a 165 mm mesh, this mesh may be suitable, and this confirms the calculation of the standard mesh size of this net by the Sachin method.
علوم زیستی دریا
Abdolah Gurani; Iman Sourinejad; Mohsen Safaei; Zahra Ghasemi
Abstract
Feeding habits and feeding indices of catfish Plicofollis tenuispinis (Pay, 1877) in coastal waters of Qeshm island around Gouran region were studied during May 2016 to April 2017 by sampling 15 fish per month throughout one year. Mean value of fish fork length was 24.43 ± 2.52 cm. Relationship ...
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Feeding habits and feeding indices of catfish Plicofollis tenuispinis (Pay, 1877) in coastal waters of Qeshm island around Gouran region were studied during May 2016 to April 2017 by sampling 15 fish per month throughout one year. Mean value of fish fork length was 24.43 ± 2.52 cm. Relationship between fork length and total weight was determined as W=0.012 FL3.066, which considering the amount of b, indicates the isometric growth of P. tenuispinis. The highest amount of gastrosomatic index was in spring and the lowest was in winter revealing that the highest feeding intensity was in spring for this species in coastal waters of western Qeshm island. Mean value of vacuity index was calculated 35.01 ± 15.91 for this species that ranks this species as a relatively edacious species. Season based analysis of VI data indicated that the lowest amount of VI or the highest number of full stomachs was in spring. Evaluation of food preference index showed that fish, shrimp, bivalves, crabs, mollusks and algae constituted 52.45, 21.31, 5.73, 4.91, 3.27 and 0.81 percent of stomach contents, respectively. Therefore, fish were the main and shrimps were the second prey priority. Crabs, bivalves, mollusks and algae were the accidental preys consumed by this species. Index of relative length of gut was 2.08± 0.26 indicating that P. tenuispinis is omnivorous in coastal waters of western Qeshm island.
Volume 12, Issue 4 , September 2014, , Pages 50-60
Abstract
Artificial breeding and subsequent release of the Caspian brown trout juveniles (Salmo trutta caspius Kessler, from Salmonidae) has been adopted by Iranian Fisheries Organization as a result of fishing pressure on its stocks. Unbalanced contribution of male breeders to F1 progeny is expected with present ...
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Artificial breeding and subsequent release of the Caspian brown trout juveniles (Salmo trutta caspius Kessler, from Salmonidae) has been adopted by Iranian Fisheries Organization as a result of fishing pressure on its stocks. Unbalanced contribution of male breeders to F1 progeny is expected with present mixed milt fertilization of gametes. Non-parametric Spearman's correlation coefficient was used to investigate the relationship between some sperm quality parameters and the contribution of Caspian brown trout male breeders at three trials. In the first trial, fertilization was performed using ova and sperm of four male and four female breeders according to routine hatchery protocol. In the second and third trials, ova and sperm of respectively four and two female and four and six male breeders with equal number of ova and the same volume of milt were fertilized. Parentage assignment of yolk sac absorbed F1 alevins was performed in FAP program using three polymorphic microsatellite loci (Str58, Str73 and Str591). More than 94% of mixed milt produced progeny were assigned to their parents in trials. Sperm motility duration was positively correlated with the number of sired progeny by each male in trials. The correlation was negative between sperm concentration and spermatocrit with amount of contribution by male breeders to F1 progeny. The results reveal the effect of sperm motility duration on the ability of alevin production by Caspian brown trout male breeders at sperm competition condition in mixed milt fertilization of gametes.
m m; m a; m s; s m; i s; h d
Volume 12, Issue 1 , April 2013, , Pages 38-49
Iman Sourinejad; Mohammad Reza Kalbassi
Volume 11, Issue 2 , November 2012, , Pages 45-57
Abstract
Conservation of genetic diversity of juveniles used for restocking of natural populations requires serious attention in artificial breeding protocol of the Caspian brown trout Salmo trutta caspius. Unbalanced contribution of male and female breeders to progeny in present artificial breeding has resulted ...
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Conservation of genetic diversity of juveniles used for restocking of natural populations requires serious attention in artificial breeding protocol of the Caspian brown trout Salmo trutta caspius. Unbalanced contribution of male and female breeders to progeny in present artificial breeding has resulted in the reduction of effective population size in breeders. Equalization of milt volume did not also result in balanced contribution of breeders. With regard to the possible effect of sperm concentration on contribution of breeders to production of progeny, effective population size in breeders and genetic diversity of progeny were determined in mixed milt fertilization of 6 male and 2 female breeders with equal sperm concentration and ova number. Parentage assignment was performed using exclusion method in FAP program by analyzing 9 microsatellite loci and choosing the 3 most polymorphic ones, Str 58, Str 73 and Str 591, in breeders. More than 91% of progeny were assigned to their parents. Effective population size was calculated as 5.24 (0.65) and the number of alleles and expected heterozygosity decreased in progeny (6.67 and 0.726 ± 0.011) compared to parents (7.33 and 0.808) significantly (P>0.05). In conclusion, equalization of sperm concentration of male breeders did not result in the balanced contribution of male breeders to ova fertilization and production of progeny in mixed milt fertilization of Caspian brown trout and genetic diversity of progeny remained significantly decreased.