Aquaculture

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Aquaculture is the cultivation of the natural produce of water (such as fish or shellfish, algae and other aquatic organisms). The term is distinguished from fishing by the idea of active human effort in maintaining or increasing the species involved, as opposed to simply taking them from the wild. Subsets of aquaculture include Mariculture (aquaculture in the ocean); Algaculture (the production of kelp/seaweed and other algae); Fish farming (the raising of catfish and tilapia in freshwater ponds or salmon in marine ponds); and the growing of cultured pearls.

Contents 1 History 2 Economic importance 3 Criticism 4 Environmentally Friendly Methods 5 References 6 External links

[edit] History

The practice of aquaculture is ancient and found in many cultures. Aquaculture was used in China circa 2500 BC. When the waters lowered after river floods, some fishes, namely carps, were held in artificial lakes. Their brood were later fed using nymphs and feces from silkworms used for silk production, and they were used as a source of food protein as well as food for the hunger season. The Hawaiian people practiced aquaculture by constructing fish ponds (see Hawaiian aquaculture). A remarkable example from ancient Hawaii is the construction of a fish pond, dating from at least 1,000 years ago, at Alekoko. According to legend, it was constructed by the mythical Menehune. The Japanese practiced cultivation of seaweed by providing bamboo poles and, later, nets and oyster shells to serve as anchoring surfaces for spores.

The Romans were quite adept in breeding fish in ponds. In Europe it became common again in monasteries during the Middle Ages, since fish was scarce and thus expensive. Transportation improvements in the 19th century made fish easily available and inexpensive, even far from the seas, causing a decline in aquaculture.

Americans were rarely involved in aquaculture until the late 20th century, but California residents harvested wild kelp and made legal efforts to manage the supply starting circa 1900, later even producing it as a wartime resource. (Peter Neushul, Seaweed for War: California's World War I kelp industry, Technology and Culture 30 (July 1989), 561-583)

The current boom in aquaculture started in the 1960s as prices for fish began to climb. Wild fish capture was reaching its peak and the human population was continuing to rise. Today, commercial aquaculture exists on an unprecedented, huge scale. In the 1980s open-netcage salmon farming was also expanding; this particular type of aquaculture technology is still a minor part of the production of farmed finfish worldwide, but possible negative impacts on wild stocks, which have come into question since the late 1990s, have caused it to become a major cause of controversy.[1]

[edit] Economic importance

In 2003, the total world production of fisheries product was 132.2 million tonnes of which aquaculture contributed 41.9 million tonnes or about 31% of the total world production. The growth rate of world wide aquaculture is very fast (> 10% per year for most species) while the contribution to the total from wild fisheries has been essentially flat for the last decade. In the US, approximately 90% of all the shrimp consumed is farmed and imported.[2] In recent years salmon aquaculture has become a major export in southern Chile, especially in Puerto Montt and Quellón, Chile's fastest growing city.

[edit] Criticism

A wide range of scientists and non-profit organizations have raised concerns about aquaculture, particularly for its impact on the environment and on animal welfare, but there is a great deal of misunderstanding regarding many of the biggest issues.

One very wide spread point of confusion and misinformation concerns aquaculture feeds. There is no true figure for the amount of feed necessary to produce a single pound of fish. This is because factors such as the species of fish being cultured, environmental conditions and the composition of the feed amongst other things impact the FCR (Feed Conversion Ratio). This figure can be as high as 2+ pounds of feed per pound of weight gained, but typically the FCR is very close to one to one. This is true for species such as salmon, cobia and tilapia if raised on the correct diet. Aquaculture feeds usually contain fish meal which is derived from wild caught fish. Fish meal inclusion levels are typically less than 50% of the diet at most with grains and other ingredients filling out the remainder of the formulation, thus showing that one pound of fish can be raised using much less than one pound of wild caught fish.

Furthermore, with modern knowledge of fish nutrition, the protein component of the diet can be from non-aquatic sources such as soybean meal and similar highly processed sources of protein that have had the anti-nutritional factors removed. This means that a linear programming economic/nutritional model, which provides the least cost diet formulation, determines the choice of ingredients in the diet. Whether fish meal and/or soy and/or corn gluten meal are used in the feed pellets has nothing to do with whether the fish are carnivorous and eat fish in the wild, but it has everything to do with economics relative to other animal feed producers (chickens, pigs, cows, etc.) who are competing for the same protein sources.^[1].

Secondly, farmed fish are kept in concentrations never seen in the wild (e.g. 50,000 fish in a two-acre area.^[2]) with each fish occupying less room than the average bathtub. This can cause several forms of pollution. Packed this tightly, fish rub against each other and the sides of their cages, damaging their fins and tails and becoming sickened with various diseases and infections.^[3]

However, fish tend also to be animals that aggregate into large schools at high density. Most successful aquaculture species are schooling species, which don't have social problems at high density. Aquaculturists tend to feel that operating a rearing system above its design capacity or above the social density limit of the fish will result in decreased growth rate and increased FCR (food conversion ratio - kg dry feed/kg of fish produced), which will result in increased cost and risk of health problems along with a decrease in profits. Stressing the animals is not desirable, but the concept of and measurement of stress must be viewed from the perspective of the animal using scientific methods and not anthropomorphic assumptions.^[4].

Some species of Sea Lice have been noted to target farmed coho and farmed Atlantic salmon specifically.^[5] Such parasites may have an effect on nearby wild fish.

For these reasons, aquaculture operators frequently need to use strong drugs to keep the fish alive (but many fish still die prematurely at rates of up to 30%^[6]) and these drugs inevitably enter the environment.

The lice and pathogen problems of the 90's were the driving forces for developing the modern treatment methods for lice and vaccines for many of the pathogens. These developments reduced the stress from parasite/pathogen problems. However, being in an ocean environment, the transfer of disease organisms from the wild fish to the aquaculture fish is an ever-present risk factor.^[7].

Given the high fecundity of most fish, a 30% loss in the larval stage is often of no significance (some species spawn several 100,000 to a few million eggs per spawn). However if a farmer is taking 30% losses on near-harvestable fish, he will not be in business for long.

The very large number of fish kept long term in a single location produces a significant amount of condensed feces, often contaminated with drugs, which again affect local waterways and their wild cousins. However, these effects are very local to the actual fish farm site and are minimal to non-measurable in high current sites. Finally, the farming of an alien species can lead to escapees with effects on the local wild population.

Other potential problems faced by aquaculturists are the legal hurdles of obtaining various permits and water-use rights, profitability, concerns about invasive species and genetic engineering depending on what species are involved, and interaction with the UN Law of the Sea Treaty. This problem has not been solved in the US, though significant marine fish aquaculture exists and is expanding throughout the world, including Canada and Mexico, with relatively little US marine aquaculture.

[edit] Environmentally Friendly Methods

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Certainly, the practice of aquaculture can have a bad reputation; however, its practice in an environmentally friendly, and economically viable, way is certainly possible. In this day of technological advances, this should be standard. One method to help minimize the above mentioned is through using a recirculating aquaculture system (RAS). A RAS is a series of culture tanks and filters, where water is continuously recycled. To prevent the deterioration of water quality (i.e. increased ammonia, decreased dissoloved oxygen, etc.), the water is treated mechanically (i.e. removal of particulate matter) and biologically (i.e. conversion of ammonia to nitrite and then to nitrate). Other filters and treatments can be incorporated such as UV sterilisation, ozonation and/or oxygen injectors to maintain optimal water quality. Through this system, many drawbacks to more “traditional” methods (i.e. cage and pond culture) are reduced including (1) minimizing/eliminating “escapees” which can affect the local genetic population and introduce disease, (2) reduce water usage, (3) reduction of harmful pollutants, such as ammonia, nitrite and chemicals to the environment and (4) increased efficiency of feed utilisation and growth through providing optimal water quality parameters (Timmons et al., 2002; Piedrahita, 2003).

While one of the drawbacks to recirculating aquaculture systems are water exchanges (normally 5% per day), to reduce the accumulation of nitrate in the system, it is possible to substantially reduce this through aquaponics (i.e. incorporation of hydroponically grown plants for commercial gain) (Corpron and Armstrong, 1983) and denitrification (Klas et al., 2006) in order to reduce the nitrate levels in the water. Thus this can, when used properly, essentially eliminate the need for water exchanges and thereby effectively “close” the aquaculture system from the environment.

A good measure of how "closed" is "closed" is to look at the cumulative feed burden (CFB kg/M3) which is a measure of the kg of feed that went into the RAS relative to the amount of water/sludge discharged. This "sludge" (a combination of uneaten food, faeces, bacteria, etc.) can be sold as excellent fertiliser to various farms, rather than being discharged to the environment. Furthermore, often species cultured in RAS have more efficient FCR's due to the ability to optimise various water quality parameters, including salinity, temperature, dissolved oxygen and pH (which is impossible on cage systems and very difficult on pond systems) which can maximise growth and increase profit (Timmmons et al., 2002). With the feed conversion ratio (FCR), one can calculate the water use per kg of fish produced.

The technical feasibility of maturing, spawning, and growing fish in RAS is well proven with "off-the-shelf" hardware available. However, economically RAS is restricted to the area of high value products such as broodstock maturation, larval rearing, fingerling production, research animal production, SPF (specific pathogen free) animal production, caviar and ornamental fish production. Other high value species include barramundi (Lates calcarifer) and various grouper species that are currently in production in Australia, SE Asia and the north eastern United States. While these species are economically feasible (due to their high farm gate price and tolerance to crowding) the use of RAS to other species may not be practical. For example, in shrimp production you often see a high tech recycle hatcheries using SPF broodstock to produce eggs and post larval (PL) shrimp (baby shrimp) for grow-out in outdoor ponds. The same is true for the use of RAS for salmon smolt production with ocean net pens for grow-out of the fish for the market.

When economically feasible, the use of a RAS has the added benefit of being marketed as "environmentally friendly."

[edit] References

• Corpron, K.E., Armstrong, D.A., 1983. Removal of nitrogen by an aquatic plant, Elodea densa, in recirculating Macrobrachium culture systems. Aquaculture 32, 347-360.
• Hepburn, J. 2002. Taking Aquaculture Seriously. Organic Farming, Winter 2002 © Soil Association.
• Kinsey, Darin, 2006 "'Seeding the water as the earth' : epicentre and peripheries of a global aquacultural revolution. Environmental History 11, 3: 527-66
• Naylor, R.L., S.L. Williams, and D.R. Strong. 2001. Aquaculture – A Gateway For Exotic Species. Science, 294: 1655-6.
• The Scottish Association for Marine Science and Napier University. 2002. Review and synthesis of the environmental impacts of aquaculture
• Higginbotham James Piscinae: Artificial Fishponds in Roman Italy University of North Carolina Press (June, 1997)
• Wyban, Carol Araki (1992) Tide and Current: Fishponds of Hawai'I University of Hawaii Press :: ISBN 0-8248-1396-0
• Timmons, M.B., Ebeling, J.M., Wheaton, F.W., Summerfelt, S.T., Vinci, B.J., 2002. Recirculating Aquaculture Systems: 2nd edition. Cayuga Aqua Ventures.

• Piedrahita, R.H., 2003. Reducing the potential environmental impacts of tank aquaculture effluents through intensification and recirculation. Aquaculture 226, 35-44.
• Klas, S., Mozes, N., Lahav, O., 2006. Development of a single-sludge denitrification method for nitrate removal from RAS effluents: Lab-scale results vs. model prediction. Aquaculture 259, 342-353.

[edit] External links

• American Society of Agricultural and Biological Engineers
• Aquaculture Association of Canada: Incorporated in February 1984, the AAC is a non-profit charitable organization with the goals of fostering an aquaculture industry in Canada, promoting the study of aquaculture and related sciences in Canada, gathering and disseminating information relating to aquaculture, and creating public awareness and understanding of aquaculture.
• Aqua Farm Designs - Benefits of Water recirculation systems in Aquaculture
• Fischtechnik is the worldleader in Planning and Construction of fish farms and recirculation systems
• FishingHurts.com/FishFarms: Criticism of aquaculture's effects on animal welfare and the environment
• Aquaculture Information from the Coastal Ocean Institute, Woods Hole Oceanographic Institution
• One Hour Radio Broadcast on Farmed Salmon in British Columbia, Canada - Kootenay Co-op Radio's Deconstructing Dinner program
• Aquaculture Resources Directory human selected reference links and downloadable reports, articles from numerous sources.
• FAO Fisheries Department and its SOFIA report on fisheries and aquaculture
• State of World Aquaculture – A summary for non-specialists of the above FAO report by GreenFacts.
• Organic Aquaculture: Articles and references on the merits and otherwise of farming fish organically.
• Aquaculture Knowledge Environment: A searchable online library of government and United Nations documents covering nearly every aspect of aquaculture from pond construction to international codes of conduct.
• World Aquaculture Society: Founded in 1970, the primary focus of WAS is to improve communication and information exchange within the diverse global aquaculture community.
• Natural Energy Laboratory of Hawaii Authority Learn how NELHA and its tenants are using sunshine, seawater and ingenuity to bring economic development and diversity.
• Friends of NELHA [FON] is a nonprofit corporation formed for education and outreach tours related to research, commercial and pre-commercial activities at Keahole Point, north of Kailua Kona, Hawaii.
• Watershed Watch Society Salmon farming and sea lice
• AquaNIC A comprehensive information server for aquaculture topics, including publications, news, events, job announcements, images, and related resources.
• American Fisheries Society
• New York Chapter of the American Fisheries Society
• National Oceanographic Documentation Center (NOAA)
• Read Congressional Research Service (CRS) Reports regarding Aquaculture
• A CATALOG OF THE SPECIES OF FISHES at California Academy of Sciences, Golden Gate Park, San Francisco, California.
• FISHING FOR INFORMATION HOME PAGE: Guide to on-line resources in aquaculture, fisheries and aquatic science
• Atlantic Salmon Federation an international non-profit organization which promotes the conservation and wise management of the Atlantic salmon and its environment.
• North American Lake Management Society
• Northeast Fisheries Science Center, Woods Hole, Massachusetts
• Advanced Technology Information Network (Calif Ag Tech Institute)
• CENET, the Cornell Extension NETwork
• Geographyinaction - Lough Swilly, Ireland example
• Aquaculture Resources for Ethno-Anthropologists News mirror service in the field of aquaculture with focus on his social effects
• Salmon farm in Mulroy Bay, Donegal, Ireland
• American Tilapia Association
• Aquaculture
• Aquaculture and the Protection of Wild Salmon

British Columbia Shellfish Growers Association