What are fish farm wastes?
The primary concern with discharge from salmon farms, from an ecological perspective, is the addition of nutrients (i.e. nitrogen and phosphorus) to the marine environment. All wild and farmed fish excrete “wastes”, or feces, as a by-product of digestion. Because the feeding of farm fish is strictly monitored by farmers, farm fish are generally more efficient at converting the material they eat into flesh than are wild fish. This feed conversion efficiency is continually improving as farmers and feed manufacturers improve feed formulations, fish husbandry practices and feeding regimes to reduce feed wastage. Feed is the single most expensive input on a farm and reducing uneaten feed is a top priority for farm managers. Other wastes produced by a farm include uneaten feed pellets, dead fish and trace amounts of other materials used on the site. All material considered “waste” is subject to handling requirements that prevent impacts to the marine environment. Fish that die due to predato
