Waste loadings from two freshwater Atlantic Salmon Juvenile farms in Scotland

Abstract

Studies of waste generation from the freshwater phase of Atlantic salmon (Salmo salar L.) production have not been substantially updated since the mid 1980's, and advances in husbandry prectices designed to reduce wastage which have taken place in that period therefore remain unconsidered. In order to determine if reductions have been achieved, two Scottish fish farms were visited on a number of occasions during one year, and outputs of suspended solids (SS), biochemical oxygen demand (BOD), total ammonia nitrogen (TAN) (NH3+NH4 +), dissolved reactive and total phosphorus (DRP, TP) were monitored. The range of waste loadings obtained were 9.1–10.0 kg TP t fish−2 yr−1, 410 kg BOD5 t fish−1 yr−1, 191–606 kg SS t fish−1 y−1, and 20.3–39.3 kg TAN-N t fish−1 yr−1. Compared to existing data, a greater range of daily waste loadings were observed, suggesting that more frequent monitoring is required to reduce variations observed in the data set, and to obtain accurate information on waste outputs from such operations. Modifications of feeding methods remains a route through which further reductions in waste outputs may be made.