...
Cage farming is comparatively simple to set up and maintain because there is no need for advanced water quality control systems. However, this reliance on nature for water management causes environmental problems, notably algae blooms caused by the concentrated waste and nutrients (Aquaculture: fulfilling its promise, 2007). The severity of these risks depend on site selection, whether the captive population is limited to the carrying capacity of the body of water, and levels of pollution from nearby sources such as industry. Ocean waters near the shore with good tidal flushing are most suitable for this type of aquaculture, and more exposed sites and attention to cage density can prevent risks to the environment (C. Goudey, personal communication, November 20, 2007). Other strategies to lessen the risk of environmental damage use shellfish, sponges, or other filter feeders to improve water quality (Shin, 2005). Also, it may be possible to use mobile cages to reduce the effects of unhealthy waste concentration (MIT Sea Grant, 1998). The first option would work well for countries where the right species are already native to the area, while the second option would allow landlocked nations or nations with little coastline a chance to develop aquaculture, as the mobile cages could be deployed in international waters. The current economic feasibility of mobile cages is unclear. While we are not currently able to provide an answer, we believe that should sufficient commercial and governmental pressure develop, means of reducing the cost of mobile-cage aquaculture would arise. These two options should provide most nations a means of performing this type of aquaculture while preserving the environment.
To attempt to reduce the risks from genetically modified fish, we recommend that genetically modified fish not be used in extensive systems, as the risk of escape is too great. Instead, we recommend that low trophic level fish that also naturally school are farmed, especially herbivores and omnivores (i.e. tilapia). Many of these fish also tend to be more resistant to disease than other fish given similar disease prevention techniques (Tilapia Disease 101), as they are used to living with poor water quality. When coupled with vaccines (already used in Norwegian salmon farms (Changing the face of the waters)), careful fish selection will reduce or eliminate the need for antibiotics and the corresponding risk of resistant strains of diseases forming. Since the selected fish should be herbivores, they can also be fed plants from land or sea, meaning that fish would not have to be taken out of the ocean to support the farming. While these fish are not necessarily popular in the open market, they can certainly provide necessary protein for many people, and can be used as feed for higher trophic level farmed fish.
Intensive Aquaculture
We also encourage the use of intensive, closed-loop systems for aquaculture. In these systems, almost all the water is recycled, with at most 5-10% of water being replaced each day (Changing the face of the waters). This also means that escape of genetically modified stock is much more difficult and that with careful monitoring antibiotic-resistant diseases can be contained, allowing the safe use of genetically modified fish and antibiotics. Furthermore, as the water is in a closed loop, the waste from the fish will not impact the surrounding environments. The ability to stack shallow tanks makes intensive farming particularly well suited to flat fish such as flounder (C. Goudey, personal communication, November 20, 2007). The primary downside is the complexity of the recycling systems. However, intensive aquaculture provides an opportunity for landlocked nations to become involved, and stacking tanks allows for large numbers of fish in a single facility.
...
NOAA recently released a 10-year plan for aquaculture in the United States (NOAA 10-year plan for marine aquaculture). We agree with its goal of increased usage of farming, particularly the use of aquaculture to rebuild stocks of wild fish. As the plan seems to be focused more on production and research goals, we feel it is compatible with our plan and encourage its adoption.
World Bank. (2007). Changing the face of the waters: the the promise and challenge of sustainable aquaculture. WashingtonWashington, DC: World Bank, c2007The World Bank.
Aquaculture: Fulfilling Its Promise. (2007). In Encyclopædia Britannica. Retrieved November 25, 2007, from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-92632
...
Purdue University. (2004). The Threats and Benefits of G.M. Fish. West Lafayette, Indiana: Muir
Muir, W. (2004). The threats and benefits of GM fish. EMBO reports 5(7). 654-659. Retrieved 26 November 2007, from http://www.nature.com/embor/journal/v5/n7/full/7400197.html
Quick Facts. In Soy In Aquaculture. Retrieved November 25, 2007, from http://soyaqua.org/quickfacts.html
...