Showing 5 results for Size
Mehrnaz Shirmohammadi, Babak Doostshenas, Simin Dehghanmadiseh, Ahmad Savari, Nasrin Sakhaei,
Volume 4, Issue 1 (6-2012)
Abstract
This study took place to survey the changes of seabed characteristic features due to trawl netting in the Bahrakan area in 2010. Sampling of sediment was carried out two times namely once before the season of the fishing activity of trawls and the other two weeks after the end of the trawls activity in Bahrakan fishing area,(northwest of Persian Gulf). For this purpose, eighteen stations were placed in 6 and 10m depths. Sediment sampleswere collected by Van Veen grab (0.025 square meters). Silt and clay percentages were 92.4 to 99.48% and 99.76 to 89.08% in 6 and 10m depths respectively,that had a significant increase in both depths after trawling (P<0.05). Also the percentage of organic substances was estimated 28.41 to 19.75% and 27.97 to 19.29% in 6 and 10m depths respectively, that had significantly increased in both depths after trawling (P<0.05).Organic carbon was recorded 12.18 to 4.9 and 12.68 to 4.7mg/l in 6 and 10m depths respectively, that wasproportionate with organic matter and increased after trawling significantly (P<0.05). In both depths, organic matter showed a significant positive correlation with the organic carbon and the percentage of silt-clay (P<0.05).Our results showed thatthe impact of trawling on sediment characteristics had not a specific differencebetween both depths.
Shahpoor Gholamy, Maryam Shapoori, Karim Mehdi Nejad, Zabihalla Pajand,
Volume 6, Issue 1 (6-2014)
Abstract
In this study, the effect of beach-seine catching activitieson changesof sediment structure of bed in Rudsar and Chaboksar areas were investigated. Samplesof sedimentwere takenmonthlywithaVan Veen grabcoveringasurfaceareaof 225 cm2 from seining and non-fishing areasofRudsarandChaboksar stations in depths of 3, 6 and 10 meters with 3 repetitions in each depth, in autumn and winter 2011.The results showa significant difference between the percentage of silt-clayinthe various sampling depths of seining area and the percentage of silt-clay in the various sampling depths of non-fishing area, in each of Rudsar and Chaboksar stations and each of autumn and winter seasons(P< 0.05). So that, the amount of silt-clay in seining area has been more than the amount of silt-clay in non-fishing area. In the Rudsar station, the amount of Total Organic Matter of the seining area were 2.6 and 2.2percent in autumn and winter, respectively, and these amounts for non-fishing area were 2.3 percent in autumn and 1.7percent in winter.Also in the Chaboksar station, the amount of Total Organic Matter of the seining area were 2.5 and 2.2 percent in autumn and winter, respectively, and these amounts for non-fishing area were1.5 percent in autumn and 1.3 percent in winter. Results indicateda significant difference between the amounts of Total Organic Matter in seining and non-fishing areas(P< 0.05). Also, the amount of Organic Matter has significant and positive correlation with the percentage of silt-clay. The results of this study show the sedimenttexture of seining areasin the various sampling depths are different form non-fishing areas.
Majid Mohammad Nejad Shamoushaki ,
Volume 6, Issue 3 (11-2014)
Abstract
In this study, the comparative evaluation of some blood biochemical parameters of rainbow trout carried out in different sizes. The study was conducted in four weight categories include 5-10, 50-100, 300-500 and 600-800 g with total of 10 fish from each group. Then, blood samples were obtained through tail vein puncture and the non-heparinized blood samples were centrifuged for 5 minutes at 5000 g, and separated serum were used to determine with an automatic analyser machine (Persige 24 I) the levels of the factors. The results of blood biochemical factors in Oncorhynchus mykiss showed there were significant differences between the different size at levels of glucose, cholesterol, triglycerides, calcium, phosphorus, chloride, iron, total protein and albumin (P < 0.05). Also, results showed there were no significant differences at values of sodium and potassium (P > 0.05). The results showed that with increasing age and size of fish the levels of cholesterol, triglycerides, phosphorus, iron, total protein and albumin were increased and the levels of glucose and chloride were decreased.But, no change observed in value of sodium and potassium blood serum. The results of this study indicated that there were significant difference in the blood biochemical parametersina species of fish in at different sizes.
Azam Makipour, Ashraf Jazayeri,
Volume 14, Issue 1 (4-2022)
Abstract
Animal systematic purpose; Identifying, naming, classifying animals and reconstructing the kinship relationships between them is at different levels of organization.Compared to other vertebrates, fishes are more affected by changes in environmental conditions, which even lead to inter- and intra-species changes in them. Actinopterygii fishes include most of the known and bony fishes of today, including mudskippers. mudskippers belong to the sub-order Gobioidei, family Gobiidae and sub-family oxudercinae.In this study, 140 mudskippers fish samples were caught from Ghannam estuary in winter 2017 to spring 2018 and were studied in terms of morphometry, morphology, and reproduction. the results of morphological and morphometric studies showed the existence of two species Periophthalmus waltoni and Boleophthalmus dussumieri in Ghannam estuary.during this study, the frequency of Periophthalmus waltoni species was higher than the other species in both autumn and spring, and Boleophthalmus dussumieri was ranked second in terms of frequency. according to the results in both identified species, the sexes were independent of each other.in terms of the presence of Sexual size dimorphism in morphometric traits, T-test and ANOVA were conducted separately for each of the male and female sexes.the results of the MANOVA test proved the population separation between males and females and showed that in both species the female is larger than the male. in both species, Periophthalmus waltoni and Boleophthalmus dussumieri, the populations of both sexes had the highest reproductive capacity in spring. the results showed that in both species, reproductive ability increases with increasing body weight and a fish with a higher weight has a higher reproductive capacity.
Hamed Raisipour Kaji, Seyed Yousef Paighambari, Mahboubeh Mirzaei,
Volume 17, Issue 1 (4-2025)
Abstract
The aim of this study was to compare two types of J-shaped hooks, sizes 6 and 12, to determine catch composition, catch rate, length frequency of captured species, and to determine the percentage of individuals caught above the length at maturity (Lm50). During each fishing operation, J-shaped hooks of sizes 6 and 12 were used alternately with Sardinella sindensis and Rastrelliger kanagurta as bait. The results of the catches were recorded separately in pre-designed forms. Sampling operations were conducted in the Ramin Port area of Chabahar County. After each fishing operation, the collected fish were weighed, counted, and their total length measured. The dominant catch composition included the species Sphyraena jello, Scomberomorus commerson, Nemipterus japonicus, Pomadasys kaakan, and Lethrinus nebulosus. During the entire sampling period, 804 fish were caught with a total weight of 751.176 kg, of which 585 fish weighing 703 kg were caught with hook number 6 (larger hook) and 219 fish weighing 48 kg were caught with hook number 12 (smaller hook). In general, hook number 6 caught more than 2.5 times more fish in terms of number and more than 14 times more fish in terms of weight than hook number 12. This indicates that the size of the fish in the fishing area and the size of their mouths were more consistent with hook number 6 and the size of the bait attached to it. So that the spanish mackerel and the common barracuda with an average length of 86 and 55 cm, respectively, had the highest weight percentage (28 and 35) and number percentage (9 and 45) among other fish caught with this hook. The results of the chi-square test showed that there was no significant difference between the catch composition of J-hooks No. 6 and 12 with sardine and indian mackerel baits (P<0.05).. The results of the Kolmogorov-Smirnov test indicated that there was no significant difference in the length frequency distribution for the species Nemipterus japonicus, Scomberoides commersonnianus , Lethrinus nebulosus, Lutjanus Johnii, Pomadasys kaakan, Scomberomorus commerson, and Sphyraena jello between the two hook sizes and two bait types (P > 0.05). By choosing the right hook and bait, we can achieve better selective fishing in fishing areas.
