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Extensive Aquaculture
Cage farming has the virtue of being 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
The second form of aquaculture we want to utilize is 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, and not spread into the wild, allowing the allowing the safe use of genetically modified fish and antibiotics. Furthermore, as the water is in a closed loop, the waste and nutrients from the fish do 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.
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There is a growing fear that genetically modified fish escaping from cage farms could seriously impact the surrounding environment. As fish from aquaculture come from Aquaculture broodstock (fish selected for spawing), this broodstock is often selected to produce the best fish breeding) is often chosen to create fish with traits optimized for aquaculture. Sadly However, these traits are often less useful, if not harmful, in the natural environment. As such, there There is a fear the that escaped fish from farms may displace natural native species, either through interbreeding or putting too much pressure on the local ecosystem (The Threats and Benefits of G.M. Fish). However, there is little evidence to support these claims But this claim is not well supported. Though some farmed fish may interbreed with wild fish, there is little evidence that these news new genes are harmful (C. Goudey, Personal Communication, November 20, 2007). However, the risk still exists, so we recommend mixing randomly selected wild fish with the broodstock, to minimize the divergence differences between the two groups.
On the issue of feed, there is great work being done on the subject of Great work is being done to find replacements for wild-caught fish in farm feed. According to (Soy In Aquaculture) "Soybean meal can replace all or most animal meals in the feeds for the majority of cultured omnivorous freshwater fish." We encourage such efforts, as they may prove key to separating aquaculture from wild fisheries and allowing near indefinite scalabilityto ending aquaculture's dependence on capture fisheries. We also recommending recommend using low - trophic level farmed fish to feed higher trophic level fish.
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To solve these problems, we propose that developing countries use cage farming to raise a large number numbers of low trophic level fish, using plants as feed and our previous suggestions to prevent negatively impacting the environmentnegative environmental impacts. These fish would be used both as a source of protein for locals , and as well as food for higher trophic level fish farmed in more wealthy nations. The purchase of fish from developing nations would allow those nations The money from exporting fish would allow the developing countries to keep the fish farms operating, thus allowing some of the raised fish to be used as food for their citizens. Corporations in developed nations, then, would use the fish from developing nations to raise higher tropic-level fish, selling them for a profit to consumers in wealthier nationshelping supply food to their citizens. In this manner, developing nations would have get both food for their citizens as well as and a new revenue stream, while developed nations could continue to consume higher trophic level fish , with very little negative environmental impact. Enforcing Implementing this plan would hinge on involve encouraging companies in developed countries to move to high trophic level farming and purchasing to purchase farmed feed fish from developing nations, thus producing a market for low trophic level farming in developing nations and encouraging them to participate. In the United States, NOAA, due to the National Oceanic and Atmospheric Administration (NOAA) is already authorized under the Merchant Marine Act , is already authorized to provide loans to help build aquaculture facilities (NOAA 10-year plan for Marine Aquaculture), if nessecary to which could help motivate corporations. By controlling the types of facilities they grant it grants loans to, they NOAA could encourage the creation of high trophic level farms that use only use sustainable feed. However, this suggestion is tentative, as the manner of best enforcement is highly dependent on other aspects of the solution, particularly in regard to international treaties and bodies. We also propose We also urge the creation of an international team of aquaculture experts to assist nations in with farm design and placement, ensuring the most environmentally friendly farm farms possible and making it them even more economically feasible for developing nations to get started.
There still remains the question of scale. Farms have produced anywhere from 63,000 to over two million pounds of tilapia per year (Sell, R., Tilapia). At an average per capita per year consumption of about about 35 pounds, a single farm could feed as many as 50,000 people (Availability and Consumption of Fish). Using This would allow the entire population of the Maldives as an example, assuming an average per capita per year fish consumption, their population of 369,031 , more than 350,000 people, (Maldives information) could to be fed with as few as eight large fish farms.
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In some cases, it may be possible to produce a even better system for a given nation. In the case of Indiasystems for particular nations. In India, for example, some cities have integrated their waste water treatment and aquaculture systems , so that human waste is used as feed for the fish , thus solving two problems simultaneously (Changing the face of the waters). However, such specialized multi-trophic multitrophic solutions are dependent on many factors, including local climate and the species involved, and are thus hard to create general guidelines for. While such systems can be very useful, designing one them is a task best done on a case-by-case basis.
The National Oceanic and Atmospheric Association, or NOAA , recently released a 10-year plan for aquaculture in the United States (NOAA 10-year plan for Marine Aquaculture). We agree with their its goal of increased usage of farming, particularly in terms of educating the public and in using the use of aquaculture to rebuild stocks of wild fish. As their plan seemed As the plan seems to be focused more on production and research goals, we feel it can still work under is compatible with our plan , and as such encourage its adoption.
Changing the face of the waters : the promise and challenge of sustainable aquaculture. Washington, DC : World Bank, c2007.
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