“As the aquaculture industry has developed and has incorporated technological advances, it has moved from extensive to intensive systems. This intensification of production methods has been accompanied by an increase in the potential threat to the already precarious ecological equilibrium in our streams, reservoirs and oceans….Recently, this intensification of aquaculture production has led to the industry being regarded as one of the leading polluters of the aquatic environment” (MacAllister and Partners: 1999, p55)
The development of intensive sea cage finfish farming has therefore overshadowed and encroached upon shellfish farming areas and traditional inshore fisheries. Such is sea cage fish farming’s global reach that its demands on fish meal and fish oil is placing pressure on capture fisheries in the South Pacific, Africa, Asia and the Arctic.
Sea cage finfish farming in particular presents insurmountable problems in terms of mass escapes, GM fish, the spread of infectious diseases, parasite infestation, the reliance upon toxic chemicals, contamination of the seabed and the bioaccumulation of organochlorine pesticides such as dioxins and PCBs (Milewski: 2001, Staniford: 2002b). Nor is the problem restricted to Scottish salmon farming (SWCL: 1992, 1993, Ross: 1997, WWF: 2000, FoE: 2001a, Berry and Davison: 2001, Scottish Executive: 2002b, Scottish Parliament: 2002a); reports have also focussed on salmon farming in Ireland (O’Brien: 1989, O’Sullivan: 1989, Oliver and Colleran: 1990, Meldon: 1993), Norway (Ervik et al: 1997, DNM: 1999), Canada (Ellis: 1996, Milewski et al 1997, Sierra Legal Defense Fund: 1997), Chile (Claude et al: 2000) and the United States (Goldburg and Tripplett: 1997). More recently the expansion of tuna, sea bass and sea bream farming in the Mediterranean has received long overdue attention (MERAMED: 2002, Studela: 2002, WWF: 2002a). Sea cages have spread like a cancer around the European coastline. As Dr Sergei Tudela of WWF states:
“Intensive industrial scale aquaculture has become synonymous with pollution and destruction of the marine environment, conflicts with other resource users, and high levels of toxins in the fish produced. The spread of aquaculture, a cause of increasing concern and growing alarm, has been described as a cancer at the heart of the coastal environment” (Tudela: 2002)
That does not mean that all aquaculture operations are fatally flawed – shellfish farming is relatively environmentally benign compared with an intensive finfish farming industry that is reliant upon inputs of feed and chemicals and discharges contaminated wastes. In the UK, Scottish Natural Heritage noted the ‘marked incompatibility’ between the shellfish and finfish farming sectors (Fagan: 2001, SNH: 2001). Supporting the expansion of shellfish farming may therefore necessarily involve supporting a reduction in sea cage fish farming: it is a case of “either….or” not “both….and”. The clash of cultures between finfish and shellfish farmers was seen last year when the Association of Scottish Salmon Growers voted for a moratorium on salmon farming (Ross and Holme: 2001). Far from criticising aquaculture per se, this paper highlights both the environmental and public health threats arising from sea cage fish farming focusing on five fundamental flaws of sea cage fish farming; namely wastes, escapes, diseases and parasites, chemicals and feed/food.
The Five fundamental flaws of sea cage fish farming:
Open sea cage fish farming, be it tuna, sea bass or sea bream farming in the Mediterranean or salmon farming in Scotland, Ireland and Norway, discharges untreated wastes directly into the sea. Nor are aquaculture wastes an insignificant source of nutrients and wastes (Staniford: 2002b). The EC admits in its ‘Strategy for the Sustainable Development of European Aquaculture’ that: “In areas with numerous farms, nutrient enrichment and the risk of eutrophication are significant issues” (EC: 2002c, p9). According to the Norwegian Directorate of Nature Management “in many countries, the aquaculture industry is the greatest source of human-created emissions of phosphorus and nitrogen” (DNM: 1999). WWF have estimated, for example (WWF Scotland: 2000), that Scottish salmon farms discharge the sewage waste equivalent of over 9 million people (Scotland’s population is 5.1 million). Both OSPAR and HELCOM have recently highlighted the problem of nitrogen and phosphorus discharges from both freshwater and marine farming operations into the North Sea and Baltic (OSPAR: 2001, HELCOM: 2001). In April 2000 the Norwegian State Pollution Control Agency admitted that salmon farms were “now major polluters” (ENDS: 2000). In the Mediterranean the EC is sponsoring research into cutting wastes due to problems with poor feed conversion in sea bass and sea bream farms (EC: 2002i).
The link between toxic algal blooms (and shellfish poisoning events such as DSP, ASP and PSP) and fish farm wastes is the subject of attention both in the Mediterranean and Scotland (Gowen and Ezzi: 1992, Berry: 1996, 1999, Davies: 2000, Navarro: 2000, Ruiz et al: 2001, MERAMED: 2002, Scottish Executive: 2002b). The Scottish Executive, for example, have hired Professor Smayda from the University of Rhode Island and Professor Rydberg from Stockholm University to investigate such a link (Staniford: 2002b). Research has also focussed on Scandinavia (Ackefors and Rosen: 1979, Ruokolahti: 1988, Aure and Stigebrant: 1990, Persson: 1991, Ronnberg et al: 1992, Braaten: 1992, Enell: 1995), Ireland (Gowen: 1990), Europe as a whole (Alabaster: 1982, Rosenthal et al: 1993, GESAMP: 1996, OSPAR: 2001) as well as other countries around the world (Nishimura: 1982, Black: 1993, ICES: 1999b, Martin: 2000, Arzul et al: 2001). An EU-funded project (AQUATOXSAL) in Latin America, conducted by French and German researchers, is also due to report later this year (Arzul et al: 1999, 2002, EC: 2002g).