Preface
As human population grows, the demand and need for fish will grow alongside it. As such, despite developments in fishing technology, the demand and need for fish will almost certainly exceed sustainable levels. Aquaculture is poised to fill the gap between fish needs and sustainable fishing, and to be scalable to meet future demands.
Aquaculture is already economically viable, with 40% of all food fish and 22% of all trade in fish already raised in aquaculture facilities, mostly from developing countries (Changing the face of the waters). However, some forms of aquaculture are far from sustainable. The most pressing environmental issues are antibiotics used on fish leading to resistant strains of disease and the aquatic ecosystem around aquaculture facilities collapsing. Some other issues that must be resolved are genetically modified fish escaping into the wild, and the need to feed fish in aquaculture facilities (Aquaculture: Fulfilling Its Promise). Our goal is to develop guidelines for an individual country to follow when creating an aquaculture industry, that would remove as many environmental dangers as possible, while remaining scalable to meet growing fish demand in the future in an economically viable way.
Since our goal for aquaculture is to partially replace wild fish with farmed fish as a food source, we focused primarily on fish farming, rather than all forms of aquaculture. For the purposes of this plan, we looked at two general types of fish farming, cage farming and intensive farming. The first type, cage farming, uses cages in large bodies of water, relinquishing control over water quality for a cheaper, simpler system. The second type, intensive, uses closed or nearly closed-loop water filtering systems, so that the fish do not interact with any natural environments.
Extensive Aquaculture
Cage farming has the virtue of being comparatively simple to set up and maintain, as there is no need for advanced water quality control systems. However, the reliance on nature for water management causes many greater environmental problems, notably the risk of algae blooms caused by the concentrated waste and nutrients. The concentrated nutrients cause the amount of algae to skyrocket, which then depletes all the resources and ruins water quality (Aquaculture: Fulfilling Its Promise). The level of these risks are very dependent on site selection and the staying within the carrying capacity of the body of water and the levels of pollution from industrial and other sources. Near-shore waters with good tidal flushing can be suitable, however more exposed sites and attention to cage density can prevent risks to the environment (C. Goudey, Personal Communication, November 20, 2007). Other solutions we have found are either to use shellfish, sponges, or other filter feeders for local water quality management (Shellfish used as a Fish Farm biofilter), or to make the cages mobile so waste does not concentrate in any one location (Model Tests and Operational Optimization of Self-Propelled Open-Ocean Fish Farm). By dispersing the waste and nutrients, it is much easier for the environment to absorb. 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 shot at aquaculture, as the mobile cages can be deployed in the open ocean, in international water. There remains the question of the economic feasibility of the mobile cages described in Model Tests and Operational Optimization of Self-Propelled Open-Ocean Fish Farm, especially in regards to developing nations. 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 extensive 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 intensive, closed-loop systems. 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 use of genetically modified fish and antibiotics. Furthermore, as the water is in a closed loop, the waste and nutrients from the fish do 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.
Genetics and Feeding
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 broodstock (fish selected for spawing), this broodstock is often selected to produce the best fish for aquaculture. Sadly, these traits are often less useful, if not harmful, in the natural environment. As such, there is a fear the escaped fish from farms may displace natural 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. Though some farmed fish may interbreed with wild fish, there is little evidence that these news 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 between the two groups.
On the issue of feed, there is great work being done on the subject of 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 scalability. We also recommending using low-trophic level farmed fish to feed higher trophic level fish.
Solving the Problem on a Global Scale
To solve these problems, we propose that developing countries use cage farming to raise a large number of low trophic fish, using plants as feed and our previous suggestions to prevent negatively impacting the environment. These fish would be used both as a source of protein for locals, 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 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 nations. In this manner, developing nations would have food for their citizens as well as a new revenue stream, while developed nations could continue to consume higher trophic level fish, with very little negative environmental impact. Enforcing this plan would hinge on encouraging companies in developed countries to move to high trophic level farming and purchasing 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 Merchant Marine Act, is already authorized to provide loans to help build aquaculture facilities (NOAA 10-year plan for Marine Aquaculture), if nessecary to motivate corporations. By controlling the types of facilities they grant loans to, they could encourage the creation of high trophic level farms that 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 an international team of aquaculture experts to assist nations in farm design and placement, ensuring the most environmentally friendly farm possible and making it 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 35 pounds, a single farm could feed as many as 50,000 people (Availability and Consumption of Fish). Using the Maldives as an example, assuming an average per capita per year fish consumption, their population of 369,031 (Maldives information) could be fed with as few as eight large fish farms.
Final Notes
In some cases, it may be possible to produce a better system for a given nation. In the case of India, 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 solutions are dependent on many factors including local climate and species involved, and are thus hard to create general guidelines for. While such systems can be very useful, designing one 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 goal of increased usage of farming, particularly in terms of educating the public and in using aquaculture to rebuild stocks of wild fish. As their plan seemed to be focused more on production and research goals, we feel it can still work under 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.
Aquaculture: Fulfilling Its Promise. (2007). In Encyclopædia Britannica. Retrieved November 25, 2007, from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-92632
Dr Shin, P. K. S. (2005). Shellfish used as a Fish Farm biofilter. In Research Frontiers. Retrieved November 25, 2007, from http://www.ugc.edu.hk/rgc/rgcnews10/Pages/2b%20Biofilter-E.html
MIT Sea Grant. (1998). Model Tests and Operational Optimization of Self-Propelled Open-Ocean Fish Farm. Haifa, Israel: Goudey.
Tilapia Disease 101. In AmeriCulture, Inc. Retrieved November 25, 2007, from http://www.americulture.com/Disease.htm
NOAA. (2007). NOAA 10-year plan for Marine Aquaculture. Washington, D.C.
Purdue University. (2004). The Threats and Benefits of G.M. Fish. West Lafayette, Indiana: Muir
Quick Facts. In Soy In Aquaculture. Retrieved November 25, 2007, from http://soyaqua.org/quickfacts.html
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