Application of Nutritional Mass Balance Models for the estimation of discharges in Rainbow Trout culture in high altitude rivers of the Ecuadorian Austro

Abstract

In the area known as Corredor de El Cajas (UTM 17M 708260 E, 9685972 S) settles the biggest quantity in farms dedicated to the aquaculture of trout (Oncorhynchus mykiss) in province of Azuay, approximately 15 Km of Cuenca city, capital of the province of Azuay. Several samplings were taken to determine the concentration of nitrates and orthophosphates among the recollection of data: feeding, biomass production, flow rate, FCR supplied by 8 trout farms with the objective of estimating the quantity of wastes outputs in aquaculture through the equations of nutrient mass-balance. The obtained values of nitrates go from 0, 12 to 0, 61 mg/l, orthophosphates from non-detectable for the method to 1,17mg/l. According to the constants used in the equations and the data obtained from trout farms the total production estimated were 5890 Kg of solids wastes, 1955 Kg of Total N and 217 kg of Total P a year, what is equal to 115 Kg of solids, 38 kg of NT and 4, 2 Kg of PT for each ton of produced fish. With a flow rate of 5 m3/s estimate for the receiving effluent it is obtained concentrations of 0,056 for SS, 0,02 of NT and 0,002 of PT. These obtained values are theoretical, but the estimate of wastes output through the nutrient mass-balance constitutes a simple, practical and low cost tool that contributes to the sustainable development of aquaculture and the environments.