Cage aquaculture in the ocean ouputs large amounts of waste into the surrounding environment. The effluent from the cages has elevated levels of nutrients, waste feed, feces and by-products such as medications for the fish. The effluent has a negative impact on the local environment. The degree of impact depends on the water movement around the cages, the assimilation capacity of the environment around the cages and the rate at which the effluent is produced. The effects of effluent on the environment is considered inconsequential to the inputs from industry and agriculture however.
That being said, the ocean floor around the cages tend to be hypereutrophic and completely anoxic up to the surface. They release sulfides and other toxins into the water as a result of reduction in the anoxic conditions of the excess organics in the sediment. The long term effects of these conditions are not known. There are no standards by which to compare internationally the effects of the cages and it is hard to determine the effects, if any, on areas away from the immediate area surrounding the cages.
There needs to be work done on how to reduce feed waste, and how to quantify the effects of the cages on the surrounding environment. To complete this project, more information is needed on operations other than cage salmon in Norway. Bibliography: Record 1 ASFA: Aquatic Sciences and Fisheries Abstracts Organic enrichment of sediments from salmon farming in Norway: environmental factors, management practices, and monitoring techniques Carroll, ML*; Cochrane, S; Fieler, R; Velvin, R; White, P Aquaculture [Aquaculture]. Vol. 226, no. 1-4, pp. 165-180. 31 Oct 2003. Record 2
ASFA: Aquatic Sciences and Fisheries Abstracts The environmental impacts of marine fish cage farms in the eastern Adriatic. Katavic, I Ribarstvo [Ribarstvo]. Vol. 61, no. 4, pp. 175-194. 2003. Record 3 ASFA: Aquatic Sciences and Fisheries Abstracts The degradation of fish-cage waste in sediments during fallowing McGhie, TK*; Crawford, CM; Mitchell, IM; O’Brien, D Aquaculture [Aquaculture]. Vol. 187, no. 3-4, pp. 351-366. 20 Jul 2000. Record 4 ASFA: Aquatic Sciences and Fisheries Abstracts The environmental impact of an offshore aquaculture system in the Gulf of Gaeta: a first approach.
Ceccarelli, R; Saluzzi, A; Fiore, V; Salerno, A; Barbera, G Biologia marina mediterranea. Genova [Biol. Mar. Mediterr. ]. Vol. 6, no. 1, pp. 294-297. 1999. Record 5 ASFA: Aquatic Sciences and Fisheries Abstracts On the impact of a sea bass (Dicentrarchus labrax L. ) cage farm on water quality and macrobenthic communities Katavic, I; Antolic, B Acta Adriatica [Acta Adriat. ]. Vol. 40, no. 2, pp. 19-32. 1999. Record 6 ASFA: Aquatic Sciences and Fisheries Abstracts Environmental impact of aquaculture. Olesen, JO FAO EASTFISH Mag. /Zh. ISTFISH. no. 5-6, pp.
45-47. 1998. Record 7 ASFA: Aquatic Sciences and Fisheries Abstracts Interactions between aquaculture and sea loch fish assemblages Carss, DN Aquaculture and sea lochs. pp. 27-32. 1996. Record 8 ASFA: Aquatic Sciences and Fisheries Abstracts Aquaculture in Atlantic Canada and the research requirements related to environmental interactions with finfish culture Stewart, JE PROCEEDINGS OF THE CANADA-NORWAY WORKSHOP ON ENVIRONMENTAL IMPACTS OF AQUACULTURE. , HAVFORSKNINGSINSTITUTTET, BERGEN (NORWAY), 1994, pp. 1-18, Fisken og Havet [FISKEN HAVET], no. 13