регистрация / вход

The Salmon Netcage Industry In British Columbia

Essay, Research Paper Salmon Aquaculture has caused or contributed to wild fish declines throughout the world. However, despite this fact, salmon aquaculture in British Columbia continues to follow a similar path which is having detrimental effects on its natural environment. The B.C. salmon netcage industry is of major concern as it is intimately linked to an array of environmental, social, and economic issues.

Essay, Research Paper

Salmon Aquaculture has caused or contributed to wild fish declines throughout the world. However, despite this fact, salmon aquaculture in British Columbia continues to follow a similar path which is having detrimental effects on its natural environment. The B.C. salmon netcage industry is of major concern as it is intimately linked to an array of environmental, social, and economic issues. Presently, the aquaculture industry is encouraged by governments as it provides a multitude of economic opportunities in coastal areas. However, studies show that the short term benefits are completely overwhelmed by a wide array of environmental and social costs. In fact, the B.C. salmon netcage industry, as it is operated presently, threatens the survival of fragile wild fish stocks, such as the Fraser River salmon, and puts human health at risk (Ellis, et al. 1997). Conducted in open net pens in the coastal regions of the ocean, this form of industrial fish production invariably results in many serious problems which need to be addressed immediately. However, before these problems can be addressed, an overview of the present B.C. salmon netcage industry is needed, along with the potential environmental impacts. At the end of the report a number of possible solutions will be discussed. The aim of this report is to illustrate the need for a major shift in the present salmon netcage industry to a more sustainable model.

Presently, most salmon, which are to be farmed, are incubated and reared for up to two years in a private hatchery before going into the freshwater phase. The one- or two-year-old smolts are then introduced to the freshwater cages. Cage size varies depending on the operation, but are usually 50 metres square by 20 metres deep. Cages are constructed of knotless nylon to reduce the degree of damage to the fish, however, all harvested fish show some damage. The number of fish started at each site also varies depending on the age in which they are started. The fish are then reared for one to two years in freshwater before being harvested (Stickney 1994). The number of Atlantic salmon smolts started in B.C. ranges from 180,000 to 250,000 at each net cage site. The harvesting of netcage salmon has changed quite drastically as the demand for farmed fish has been steadily increasing. Subsequently the harvesting of netcage salmon now takes place year round (Ellis, et al. 1996).

Interestingly, the production rate in B.C. for 1996 was approximately 32,000 tonnes of live weight (or harvested salmon). However, approximately 118,000 tonnes of fish feed was needed to rear B.C.’s netcage salmon. This results in a huge net loss of protein that is available for human consumption, (Appendix A), (Ellis, et al. 1996). Thus, an immediate problem with salmon farming can be linked directly to the source of food, which is mainly grain and other fish. The fact is, that the efficiency can never be absolute when raising salmon, as enormous amounts of valuable nutrients are lost in the process of transforming fish and grain into feed for aquaculture salmon as opposed to being used directly as human food. Based on this it becomes clear that intensive aquaculture does not represent a real solution – possibly the opposite.

In addition to the net lose of protein in salmon aquaculture, the techniques of fish farming used today in British Columbia, which were discussed above, pose a grave and immediate danger to coastal environments. The use of open netcages invariably results in large quantities of nutrients and organic matter being emitted directly into the coastal environment. As fish feces begin to accumulate it becomes increasingly dangerous to both passing wild fish and the fish farm industry itself, as many fish pathogens may be contained within the feces. However, by using a technique known as fallowing, whereby farm activity is rotated between tenures, the adverse environmental impacts can be reduced (Ellis, et al. 1996). Studies show that effective fallowing of marine netcage aquaculture takes up to five years (Cross and Kingzett, 1994). Presently, in B.C. salmon netcage operations use a two-year rotation of Atlantic salmon at each tenure, as netcage operations are not required by law to fallow (Ellis, et al. 1996). Thus, in B.C., huge volumes of fish sewage are continuously being dumped into receiving waters with little or no treatment. The reality is that this is not only devastating to the environment, but also leads to declining yields among older tenures. However, the industry can simply ignore the long term costs of not fallowing as they can relocate to new regions of the coast once their profits have been made and the site is no longer viable. Therefore, if netcages are to be used, the industry must be forced to fallow, in order to allow the natural environment to dispel the negative effects of high discharges of fish feces.

Another major risk is that wild fish could be decimated by the spread of virulent diseases. As was mentioned above, the cages float in the ocean, and are filled with high densities of farm fish. The jammed and stressful conditions of the netcages mean they can become breeding grounds for disease epidemics. Further, many of the netcage operations in B.C. use fish grown from imported Atlantic salmon eggs. Atlantic salmon are preferred by the industry because they grow more rapidly, and they are more docile. The trouble is, the imported fish can bring new diseases with them which can spread among B.C.’s native fish populations (Pillay, 1992). To combat this situation the aquaculture industry uses a variety of antibiotics, pesticides and detergents. However, many of the chemicals used to control disease are toxic to a range of species, persistent in the environment and able to accumulate in biological tissues. They may create problems with residues in the cultured fish, affect the surrounding environment, and allow antibiotic-resistant bacteria to enter the environment. Some of these bacteria may be pathogenic to marine species or even humans (Ellis, et al. 1996).

In addition to the spread of disease, the farming of Atlantic salmon may in fact alter the genetic composition of wild stocks as each year in B.C. there are a huge number of escapes. In fact, from 1988 to 1992 there were approximately 850,000 Atlantic salmon which escaped from B.C. fish farms (Ellis, et al. 1996). If the farmed fish end up interbreeding with wild stocks there is an extremely high potential of reducing the fitness of wild species and thus, threatening their long-term survival (Flemming, 1996).

In British Columbia, the government is failing to protect coastal and marine ecosystems from the destructive impacts of aquaculture. In particular, the rapid expansion in development of intensive aquaculture for high value salmon, has resulted in widespread degradation of the environment and displacement of coastal fishing and farming communities. The fundamental problem is that the netcages are open to the ocean environment. Escapes of farm fish are inevitable, leading to genetic and other harmful interactions with wild fish. Further, sewage from fish feces and other wastes build up in the areas around the netcages, which contain disease pathogens and drugs. Therefore, the salmon netcage industry in B.C. as it exists today is not sustainable. To make a move to a more sustainable model a number of things must occur. Firstly, open cages must be replaced by closed containment systems immediately. These systems are ‘closed’ in that an impermeable membrane separates the fish from the surrounding marine environment which allows the full treatment of sewage and prevents contact with wild fish. Just recently, in response to the David Suzuki Foundation recommendations, the B.C. Salmon Farmers Association (BCSFA) in cooperation with the B.C. government stated that they were “committed to undertaking the world’s first commercial trials of closed containment salmon farm systems right here in B.C.” (CNW, 1997). In fact, already a system has been installed near the Pacific Biological Station, Departure Bay B.C., for testing and demonstration purposes. Secondly, the B.C. government, in collaboration with organizations such as the BCSFA, must ensure that dependent coastal communities and artisanal fisheries are not adversely affected by aquaculture development, and prohibit the development and use of genetically manipulated and exotic species such as the Atlantic salmon. Further, proponents of intensive aquaculture must begin accepting responsibility for demonstrating that proposed projects will have no significant impacts on the environment or on local biodiversity. As salmon farming operations exist today in B.C. the environmental and health problems remain significant and seem set to increase. Therefore, instead of waiting until it is too late, we as British Columbians must change our aquaculture practises before the environment forces us to change them.

Works Cited :

“B.C. Salmon Farmers Call On Provincial Government To Implement Environmental Assessment Review Recommendations.” CNW. Sept 24. 1997.

Cross, S.F., and Kingzett, B.C. 1994. Mandatory Environmental Monitoring Program for the Marine Net- cage Culture Industry: Program Review and Evaluation. Prepared by Aquametrix Research Ltd., Sidney,B.C., for the Ministry of Environment, Lands and Parks. Environmental Protection Department. Victoria, B.C. pp.35

Ellis, D.W. Net Loss: The Salmon Netcage Industry in British Columbia. The David Suzuki Foundation, 1996.

Flemming, Ian. “Salmon at Risk.” Globe and Mail. January 15, 1996.

Pillay, T.V.R. Aquaculture and The Environment. Toronto: Halsted Press-John Wiley @ Sons Inc, 1992. pp. vii- ix,1-3

Stickney, R.R. Principles of Aquaculture. Toronto: John Wiley @ Sons Inc, 1994.

366

ОТКРЫТЬ САМ ДОКУМЕНТ В НОВОМ ОКНЕ

ДОБАВИТЬ КОММЕНТАРИЙ [можно без регистрации]

Ваше имя:

Комментарий