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Rainbow trout, Oncorhynchus mykiss is the most important cold water farmed fish in Iran. Several cultivated stocks have been imported to Iran and some fish farms have focuesd on the culture and breeding of these stocks all around the country. In this study, the genetic structure of Spanish and American stocks of rainbow trout was investigated using 4 pairs of microsatellite markers and 30 specimens of fish from each stock. Allele sizes at OMY77, OMY325, OMM1329 and OMM1332 loci were in the range of 102-178, 100-150, 122-198, 172-204 bps respectively. Average number of observed alleles in American and Spanish stocks was 11 and 11.5, respectively. Average number of effective alleles in Spanish and American stock was 8.65 and 8.03, respectively. The mean of observed heterozygosity for American and Spanish stocks were calculated as 0.59 and 0.63, respectively. The mean of expected heterozygosity for both stocks was very similar (around 0.86). The results showed a significant deviation from Hardy-Weinberg equilibrium at seven out of eight loci × stock. AMOVA test showed low (7%) genetic diversity between stocks, while the most (93%) genetic diversity was observed within stocks. Genetic identity and genetic distance between stocks were 0.831 and 0.186, respectively. Fixation index FST was calculated based on allelic frequency between two stocks was 0.012 with no significant difference between 2 stocks. The results of this study showed that while there was considerable genetic diversity within Spanish and American stocks, two stocks were very similar and showed very insignificant genetic differentiation based on 4 microsatellite studied loci.

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The goal of this research was considering the reasons of policy holder satisfaction of breeding freshwater fish farms with agriculture insurance in Mazandaran province. The population of this research was the number of 63 freshwater fish breeders in Mazandaran province had assured their farms through Agricultural Insurance Fund during years 88 to 92 and they have utilized questionnaires for field data collection, its validity was approved by experts’ panel and its reliability was approved through utilization of Cronbach’s alpha coefficient (0.85). the variable " Agricultural Insurance Fund has considered on our complain on time" had more sound on satisfaction at the level of %30 followed by the variable " I am satisfied with specification and estimating damage of agricultural insurance" with the level of %28 and" the distance between damage and the time of compensation assessment by Insurance Fund is suitable " in level of %23  and" mangers and personnel attitude of Agricultural Insurance Fund is suitable" in level %20 are effective in measure of satisfaction. Obtained results from the research indicate that the main dissatisfaction of breeders had been about "becoming time-consuming between damage and compensation payment, being unsuitable and defective of specification and estimating compensation process, the way of considering on complain and demand of breeders and the way of managers and personnel of Agricultural Insurance Fund attitude and behavior.

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Water quality of the Samsami and Dinaran rivers of Chaharmahal and Bakhtiari province were assessed in year 1393. For each river, 7 stations were determined. Water sampling has been done monthly (May to October) and samples, under standard situation, were sent to laboratory for assessing: Nitrite, Ammonium, Soluble Phosphate, BOD₅, COD, TSS, TDS, Cu, Zn, Hg, Cl^-, Organophosphate toxins, pH, Malachite green and EC. Soluble phosphate was higher than standard in studied rivers (p<0.05). There were increasing trend for all recorded parameters from first to last station. Except for the low number of stations, BOD₅ and COD were equal or lower (p<0.0001) than its standards. There were some malachite green in studied rivers especially at their last station (p<0.002). Other parameters were lower than standard for two rivers (p<0.05). Generally, water quality of these two rivers was absolute, but, for development new trout culture farms, Nitrite, Phosphate and Malachite green must be controlled.
 
 

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The current research has been conducted to identify the impact of the spread of the Covid-19 pandemic on the breeding and propagation centers of coldwater fish, including the impact of inputs, production, and the supply process. The statistical population of this research was the propagation, rearing, and intermediate farms of coldwater fish in Tehran, Mazandaran, Fars, Kohgiluyeh and Boyer Ahmad, Kerman, Guilan, Zanjan, Chaharmahal and Bakhtiari, Isfahan, Lorestan, Markazi, and West Azerbaijan provinces. The number of farms investigated in this research was 75 farms. The results of this research showed that the outbreak of the Covid-19 disease had a strong impact on production activities in coldwater farms. For example, the fresh sales were decreased in 78% of the investigated farms. Restaurant demand for fish decreased in 82% of farms, and overall 90% of respondents reported a decrease in fish purchase demand in their sales markets. Also, the supply of inputs such as fish feed, eggs, and fry was faced with problems in more than 80% of the farms. The same problem was observed for selling products, where 93% of the respondents believed that the main reason was the restrictions on travelling during the lockdown. Finally, 93% of the respondents stated that the restrictions created during the outbreak of the disease had a negative impact on the production process, of which 67% declared that this impact was great. The results of the current research indicated the initial shock to the country's coldwater aquaculture industry in the early days of the outbreak of the Covid-19 disease. Results of present study are consistent with similar studies conducted in other countries. For this reason, using the strategy of endurance during the occurrence of similar crises through the compilation of government guidelines to support the aquaculture industry is known as the most appropriate strategy for the continuation and survival of the industry.