Environmental effects of the cold water fish farms effluents on the water quality of Gamasyab River as their main source of water supply in the west of Iran

Rainbow trout (Oncorhynchus mykiss) is one of the most-widely cultivated cold fresh water fish in the world. Gamasyab River, with a length of about 200 Km, is one of the longest rivers of Iran. The aim of this research is to determine the effects of trout farm effluents on this river water. From a total of 24 trout farms in the area, four farms were randomly selected and three sampling stations were chosen at each selected farm. Measured water quality parameters were temperature (T), total suspended solids (TSS), total dissolved solid (TDS), dissolved oxygen (DO), pH, five-day biochemical oxygen demand (BOD_5), chemical oxygen demand (COD), ammonia-nitrogen (NH_4-N), nitrate-nitrogen (NO_3-N) and phosphates (PO_4-P). Based on the laboratory analysis, DO in the river water was more than 6 mg/l in all cases. There were significant differences in six variables of T, BOD, COD, NO_3-N, NH_4-N, and TSS of all water samples taken from the second sampling stations between dry and wet season. The DO concentration in Gamasyab River decreased between the water inlet (first stations) and outlet (second stations), but increased in third station. Trout farm effluents had significant impact on the TSS content of the river. This significant increase in TSS concentrations is expected to have occurred due to cleaning or harvesting activities on any of the farms. The results of the study showed that, in all of season, the amount of TSS in the second stations was not equal to the standards of the Department of Environment Protection (40 mg/L) for discharging into river systems

Ecological capability evaluation for aquaculture activities by GIS

Geographic Information System (GIS) is the best suitable system for land evaluation. In this research, at the first step, the Makhdoum's model is introduced‚ and then Hamadan Province, from aquaculture point of view and capabilities of the lands to fulfill aquaculture activities is evaluated. GIS was used for the mentioned purposes. The software used was Arc View (version 3.2 a), with the UTM projection. For evaluation, Mc Hark method of Maps overlaying was utilized. According to the results, the suitable surface area for aquaculture activities was introduced, which was equal to 13.1 percent of Hamadan Province. According to the evaluations, this province has limited potentials for aquaculture activities. Therefore, it is necessary to pay attention to these limitations in development plans