Evaluation of the Effluents Characteristics in Land-based Trout Farms (Fethiye, Mugla) within the Frame of Legal Arrangements

Some water quality properties (water temperature, dissolved oxygen, pH, ammonia-nitrogen, total phosphorus, suspended solid matter, biochemical oxygen demand, chemical oxygen demand) in effluentsof medium (200 tons year-1) and big scaled (2500 tons year-1) with sedimentation ponds rainbow trout (Oncorhynchus mykiss, Walbaum 1792) farms which are established on Esen Creek (Fethiye, Muela) havebeen monitored monthly basis between October 2009 and September 2010. Furthermore, for each farm the nitrogen and phosphorus load is estimated for per ton of fish produced and per ton of feed used.During the research period, the determined water quality features have generally shown significant statistical differences according to effluents of medium and big scaled trout farms (p<0.05). Concentrations of ammonia nitrogen (0.19 - 0.38 mg/L), total phophorus (0.13 - 0.64 mg/L) and supended solid matter (14.75-127.0 mg/L) in farm's effluents are higher than the limit values of the relevant regulations in different countries and biochemical oxygen demand values (2.20 - 5,62 mg/L) are lower than the target values mentioned in the international legal regulations. It is estimated that in the big scaled farm (FCR: 0.80) the nitrogen load for one ton of fish produced is 59.08 kg and 4.01 kg phosphorus load; in the mediumscaled farm (FCR: 1.25) the nitrogen load for one ton of fish produced is 106.25 kg and phosphorus load is 10.75 kg. Some suggestions are proposed in the light of quantitative findings obtained during the present research.