Comparison of growth and survival rate between import and native rainbow trout (Oncorhynchus mykiss)

Rainbow trout is only species of cold water fishes which is rearing and propagation in Iranian fishery farms. Along of develop aquaculture industries increase request of best produces such as trout eyed eggs and larva. For this reason fishery farmers must be to provide that the way of import of other countries, such as: Denmark, Norway and France. As for this importance subject and unknown basic information about preference ratio for doing it, we needed to study about that to answer the suppliant questions. In this study carried out 3 test groups (3 treatments with 3 repetitions) and compared specific growth rate (SGR), condition factor (CF) and survival rate (SVR) between in this groups. Statistical analysis were significantly difference of increase rate of length and weight in French group with other groups (p<0.05). Compared of main factors (SGR, CF, SVR) in French test group were significantly difference with other groups (p<0.05). Survival rate percentage in Iranian treatments (SVR=%67) were significantly with the others (p<0.05). This ratio respectively in Danish and French treatment was %54 and %48

The production of all-female in rainbow trout (Oncorhynchus mykiss) using indirect feminization

The sex reversal technique in fish is widespread in many countries. The development of these techniques is desirable because rainbow trout males reach their gonad maturity earlier compared to the females. Rainbow trout alevins were treated with 17α-methyltestosterone incorporated in the diet (0.5. 1.5, 3, 6 and 10 mg/kg) for 60 days from the beginning of first feeding. Sex was determined at 180 and 680 dpf by sampling fish (n = 20) from each group and examining gross gonadal morphology under a dissecting microscope. Also sex reversal ratio and growth performance were determined in hormone-treated groups. These sex reversed functional males were reared for brood stock until they attained sexual maturity. At the end of experiment, normal rainbow trout eggs were fertilized with the sperms taken from sex reversed males for producing all-female populations. Examination of the results showed that 17α- methyltestosterone was effective in all treatment. The highest sex reversal ratio with 100% was observed in group treated with 0.5, 1.5 and 3 mg/kg 17α- methyltestosterone. The highest live weight ratios were observed in groups fed with 6, 0.5 17α-methyltestosterone and control group. Female progeny produced from the sex reversed males were 100 % in all males that sired offspring. All female trout stocks produced by this method have advantage in rainbow trout culture since the fish is not meant for direct human consumption and is used to generate brood stock, therefore, difference of growth parameters do not influence the success

The creation of genetic basic population of rainbow trout (Onchorhynchus mykiss) based on study of genetic variation in brood stocks using microsatellite

In order to perform the project, 446 samples of rainbow trout (Onchorhynchus mykiss) from 24 different regions in Iran were collected. About 2-3 g of caudal fin samples was collected from each specimen and preserved in absolute ethyl alcohol and then transferred to the genetic laboratory. Genomic DNA was extracted using the phenol-chloroform method and then DNA content and quality was determined using spectrophotometry and agarose gel electrophoresis, respectively. Polymerase Chain Reaction (PCR) of genomic DNA fin samples was carried out using 10 pairs of microsatellite primers. All PCR products were electrophoresed on 6% polyacrylamide gel and stained with silver nitrate. Following the scoring of alleles, all parameters including allelic frequency, effective number of allele, observed and expected heterozygosity, shanon index, measurement of similarity and genetic distance and Hardy-Weinberg equilibrium, Fst , Rst and gene flow were calculated using AMOVA analysis in the GenAlex and Popgene programs. The results showed that 8 pairs of microsatellite primers were polymorphic. In total, 50 alleles were determined with the range size of 64-280 bp. The locus omyf had maximum number of allele (26) and loci OTSG 474 and Strurruta58 had minimum number of allele (5). The observed heterozygosity was between 0.86 and 0.964. Hardy-Weinberg departure was observed for all loci from farms 18, 15, 4, E20 and 21 and were disequilibrium (P<0.05). The farms 14, 8, 7 and 6 were equilibrium at 3 loci, but showed disequilibrium in other loci. The other farms were equilibrium at 1 or 2 loci and disequilibrium at 8 or 9 loci. The FST results showed that maximum FST (0.24) were between farms 1 and 11in which had minimum of gene flow (3.7). Minimum FST (0.04) were between farms 8 and 9 in which had maximum of gene flow (346). Based on the results of AMOVA analysis, significant differences were detected between all farms (P<0.01). Furthermore, based on Nei 's standard (1972) maximum genetic distance (0.89) were observed between farms 2 and 11 and maximum genetic similarity (0.15) were detected between farms 3 and 4. This result suggests that the unique genetic variation of rainbow trout in hatchery farms of Iran represents a highly valuable genetic resource and provide useful information for creating a based population in the future breeding programs