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All About Aquaculture
Ever wondered about the new-fangled aquaculture industry? Here is your chance to find out about it!

Introduction
History of Aquaculture
Types of Aquaculture
Aquaculture Systems
Plants and Animals
Aquaculture and the Environment
Aquaculture and Commercial Fishing
Is It Safe to Eat Farm-raised Fish?
Building your own Hatchery

 

Note: words in red link to an online glossary (or dictionary) of related terms.

Introduction
Aquaculture is the art, science, and business of producing aquatic plants and animals for human use in a controlled environment. Given our highly health-conscious society and the declining wild fish populations, there is a vital need for aquaculture, which produces reliable, high -quality protein such as fish, shellfish and plants for consumers.

Aquaculture, like agriculture, is the cultivation and harvest of plants and animals for human use. Both aquaculture, and agriculture are farming, but aquaculture — farming in water — requires a different set of knowledge, skills and technology. Plants and animals are held in water in a variety of systems, fed continuously, harvested and sold to distributors.

Fish farming is rapidly expanding in the United States and in New England in particular. Wide ranges of species are being grown nationally, with catfish most popular in the South, and salmon and oysters dominating the Northeast.

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History of Aquaculture
Aquaculture has been around for centuries, in one form or another, all over the world. Chinese manuscripts from the 5th century B.C. indicate that the Chinese practiced fish culture in ponds.1 They raised mud carp, which feed on plants and animals from the bottom, silver carp which feed on phytoplankton and zooplankton, and grass carp which feed on floating aquatic plants.2 This method allowed for efficient use of the ponds. The fish were captured from the wild when they were still juveniles and then raised in the ponds to adulthood.

Like the Chinese, the ancient Egyptians may have raised fish in small ponds. Ponds that seem to contain intensive fish culturing have shown up in Egyptian hieroglyphics.1 The ancient Romans followed in the Egyptian footsteps by culturing mussels in small ponds.1 Aquaculture occurred in Japan, for pearls, Indonesia, for brackish water fish, and even in Medieval Europe, where people would catch small fish and put them in moats to fatten.2 In all of these cases, fish were captured as juveniles and then raised to maturity to be eaten. If the fish spawned and reproduced, it was a side effect rather than the goal.2

It was during the mid-16th century that modern aquaculture began. In 1733, a German farmer gathered trout eggs, fertilized them, hatched them, and then grew the larvae to adulthood.1 Early modern aquaculture was limited to salmon, shrimp, and more luxury seafood, but as it became more economical, more common species began to emerge in fish farms.1 During the Depression, American aquaculture got a push forward with the “Farm Pond” program, which was part of the New Deal. Farmers were assisted by the government in the construction and stocking of farms in an attempt to increase their income.2 Trout has been cultured commonly since the 1950s as a recreational fish to restock ponds and rivers.3

Currently, there are 20 species commonly cultured in the United States and 100 species cultured worldwide.3 Research conducted at the MIT Sea Grant Finfish Hatchery and similar hatcheries is attempting to increase that number to reduce our dependence on wild stocks.

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Types of Aquaculture

TautogDepending on the requirements of the species, the animals or plants can be raised in a warm, cold or marine environment.

In warm fresh water, catfish, crayfish, baitfish, sportfish, tilapia and ornamental fish are grown.
Cold fresh water trout and salmon are grown. In mariculture, which uses brackish or salt water, brackish clams, oysters, seaweed, mussels, shrimp, haddock, cod, salmon, and flounder are grown.

Each life stage of these species can take place in several different growing environments. Depending on the species being cultured and well as the location of the facility ponds, tanks, open ocean, raceways, or cages would be choices for rearing systems.

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Aquaculture Systems
Aquaculture occurs in three different forms: ponds, pens, and recirculating tanks. Pond aquaculture is most like farming. With this method, areas of land are enclosed by dikes and flooded. Fish, most commonly catfish or shrimp, are then added to the pond. The fish or shellfish are fed on a regular schedule, and a clean source of water is used to keep the pond in the proper condition for healthy growth.

Floating pens are the most common methods for growing marine finfish, such as salmon, in protected coastal waters. One of the biggest concerns in aquaculture is continuously providing fresh, clean water for the fish. In large enclosures made of netting, fish can enjoy a natural flow of water and all the food they can eat. This open-water approach is also used in growing marine shellfish, with the natural currents bringing both clean water and plenty of food for filter-feeding bivalves such as oysters, quahogs, and scallops.

The open ocean method of aquaculture is similar to the pens, but consists of pens located offshore. One advantage to culturing fish offshore is that pens can be located on sites that are not already being used for recreation or fishing. The fish are fed on a regular schedule, while shellfish are provided with plenty of food by the natural currents. Commercial fishing vessels can transport or harvest the fish, which creates more jobs within a community currently struggling to support itself.

The newest kind of aquaculture employs recirculating systems to clean and re-use water. "Recirc" systems are made up of several components that filter the culture water of waste and toxins and treat it to reduce the bacteria and virus load. Because one can control the environmental parameters in this recycling system, growers can carefully control water quality, and “recirc” systems eliminate the risk of weather-dependent ponds and pens. Recirculating systems also use far less water than other methods and any discharge water can be thoroughly treated to make sure that no waste is released into public waters. Check out this animated recirculating system.

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Many kinds of plants and animals are grown

Freshwater   Varied waters   Saltwater
Ornamental Striped Bass catfish   Red Drum   Hydroponic seaweed
Hydroponic lettuce Trout   Shrim   Crawfish
Hydroponic spices Tilapia   Shellfish   winter flounder
Tilapia Yellow Perch   Salmon   Shrimp
Baitfish Walleye   Yellow Perch   Shellfish
Hydroponic seaweed Baitfish        

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Aquaculture and the Environment
Aquaculture, like agriculture is the cultivation and harvest of plants and animals for human use. Both are farming, but aquaculture – farming in water – requires a different set of knowledge, skills and technology. Just like agriculture, aquaculture comes in many different forms, with different environmental effects. Aquaculturists are working to reduce any negative effects that fish farms may have.

Pond aquaculture, which is most commonly used to cultivate shellfish, consists of pens that are placed in rivers or estuaries.4 Water flow and feed for these pens come from the natural sources available.5 These pens can change the flow patterns and speeds within the pens.4 However, the farms can help reduce the over-enrichment of many coastal waters due to runoff from agriculture and human activities, which improves the quality of the water and the wild populations.6

Recirculating aquaculture systems are used to cultivate many different types of fish and plants. These systems use a filtration system to clean and re-use the water, and the fish are fed with artificial food sources.5 Because this type of aquaculture is mainly self-contained and can control what it outputs, it has a limited environmental impact. The fish are raised at high densities, making them economical. Pen culture, occurring in the open ocean, depends on natural water flows and artificial feed. The fish, most commonly salmon, are cultured at a high density, which can cause problems with disease and parasites.7 When antibiotics are included in the food to treat disease, the wild animals in the area, especially bottom feeders, can consume the chemicals in the excess food.7 However, antibiotics are now administered individually, and pens are isolated while the fish are being treated. 5

One environmental concern common to the systems that use artificial feed is a dependency on baitfish for the fishmeal. Fishmeal is used in the production of food for fish, dogs, cats, and several farm animals. Because using fishmeal for the increasing volume of pet food can put stress on the wild stock, research is being conducted on the use of soy products to replace the fishmeal.

An environmental concern common to the systems that use natural water flows is eutrophication due to excess feed and waste. Eutrophication is the process by which a body of water can become enriched in dissolved nutrients, promoting algal growth.8 It is a problem because an excess of nutrients degrades the water quality, and creates an imbalance in the food web.8 Culturing plants near the pens that feed on the nutrients that the fish give off as waste helps the problem, as does treatment similar to that at a sewage treatment plant. 8

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Aquaculture and Commercial Fishing
Some people are concerned that aquaculture will take away jobs and income from commercial fishermen. This is not the case. The fact is that there are more people in the world, more people wanting to eat fish because it’s a high-quality source of protein, and less fish in the oceans to feed them. Aquaculture is working with commercial fishing to fill the gap between supply and demand with fish.

Commercial fishing is an important industry for American workers. It provides jobs for fishermen as well as ice suppliers, processing plants, and local merchants.9 Many communities survive because of the fishing industry, and are struggling with current stricter regulations.10 Aquaculturists are taking advantage of the infrastructure that is already in place for commercial fishing to market their fish. This means that jobs are created in areas that are dependent on fishing for income.11Both fishing and aquaculture have their own environmental concerns, which must be taken into account. Commercial fishing has developed over the years to be extremely efficient in its ability to catch a large amount of fish in a small amount of time. Unfortunately, one of the side effects of this efficiency is bycatch. Bycatch is when fishermen catch fish other than their target species. Because of the way licenses are issued, these extra fish must be thrown back, which puts stress on the fish population.12

One great advantage of aquaculture is its ability to breed fish that are ideal for the market, thereby ensuring demand. Fish from farms can also be fresher and available year round.13 But if these selectively bred fish escape, they can breed with fish in the wild and threaten the natural biodiversity found in species.14 Fish feed from farms can also threaten ecosystems if it is present in excess, or if it contains antibiotics.12

As aquaculture grows and expands to new areas of the world, it will have to depend on the knowledge of local fishermen. Fishermen have in depth knowledge of local fish, weather, and migration patterns. With the help of fishermen, aquaculturists can set up farms where they will not interfere with local fish and fishermen. Off-shore fish farms may also be able to get assistance from fishermen harvesting catch on their vessels.

If aquaculture and commercial fishing work together, the advantages from each will help to create a self-sustaining, efficient seafood market in America. The high-density fish farms will be able to supply more fish to the American market, alleviating the need to import seafood.13 Since these farms are not dependent on wild populations, the stress that is currently put on them can be alleviated, and eventually the ecosystems will be healthy again.

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Is it safe to eat Farmed Fish?
Fish have been farm rasied for centuries to provide protein in places where it was hard to get. A healthy diet should include a variety of protein sources. There are many benfits to including fish in your diet:

  • Fish contain Omega-3 fatty acids, which may help reduce the risk of heart disease and cancer, lower blood pressure, reduce depression, and relieve the pain of rheumatoid arthritis.15
  • Omega-3 fatty acids are essential to brain, nerve, and eye development, and may help reduce the symptoms of ADHD and the risk of asthma.16

Recently, there have been concerns about how safe it is to eat farm-raised fish. Limited research has found that some farmed raised fish contained harmful chemicals called polychlorinate biphenyls (PCBs).15 However, there are safeguards implemented by the government to insure that the food we consume is safe for us:

  • FDA regulations limit the amount of PCBs in seafood to 2,000 parts per billion, which is 100 times larger than the amount of contaminants found in the recent studies.15
  • EPA guidelines say that fish containing levels of PCBs between 24 and 48 parts per billion should be limited to 8 ounces a month, which is approximately 3 servings.15
  • EPA regulations are based on eating fish from one contained source, which would increase the likelihood of consuming too much of a single contaminant.15 Generally, eating protein from a variety of sources is healthier.

These regulations exist because it is known that wild fish can be contaminated with heavy metals, such as mercury, as well as PCBs, dioxins and other pollutants that they absorb from their food.16 The levels of PCB contaminant found in wild and farm-raised fish are similar.17 However, work is underway in the aquaculture industry to reduce the source of contamination in fish feed, which would eventually make farm-raised fish healthier than wild fish.18

The contamination levels that the FDA allows in marketed fish are low enough that you can eat two meals of fish per week without worrying about health risks.19 You can also eat more than two fish meals per week if this is not done regularly.19 With the advance of current aquaculture research, the number of servings recommended per week will increase, making it easier to gain the health benefits available from fish.18

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Building your own recirculating hatchery
Aquaculture is an excellent tool to be used in an educational setting. Several subjects can be incorporated into aquaculture: history, English, math, biology, chemistry, economics and engineering. A real life recirculating system that mimics a production scale system can be used an exciting tool to demonstrate a growing industry in a classroom or school. It is self-contained, requires minimal maintenance, and user friendly to teachers and students. One could set up a fish tank and use that to teach many of the same subjects of study, but by using a real life model of a industrial system, students will be able to identify with the process of building a functioning system out of several different types of materials and tools.

 

References:

1 http://www7.taosnet.com/platinum/data/light/whatis/history.html
2 http://www.cyfernet.org/curricul/aquacul.html
3 http://ag.arizona.edu/azaqua/extension/Classroom/overview.htm
4 http://www.dnr.state.sc.us/marine/mrri/shellfish/clam.htm
5 http://www.csa.com/hottopics/aquacult/oview.html
6 http://www.fao.org/docrep/003/w7499e/w7499e14.htm
7 http://www.oceansatlas.org/servlet/CDSServlet?status=ND0xODA0OCY3PWVuJjYxPSomNjU9a29z
8 http://ressources.ciheam.org/om/pdf/c55/01600222.pdf
9 http://www.theissue.com.au/www_root/pdf/ti0202fe.pdf
10 http://eesc.orst.edu/salmon/human/commfish.html
11 http://seagrant.gso.uri.edu/noreaster/noreasterFW97/aquaculture.html
12 http://www.pisces.demon.co.uk/factshe6.html
13 http://seagrant.gso.uri.edu/noreaster/noreasterFW97/aquaculture.html
14 http://eesc.orst.edu/salmon/human/hatcheries.html
15 http://www.salmonfarmers.org/nutrition/safety.html
16 http://www.newmediaexplorer.org/chris/2004/01/10/farmraised_salmonpcb_levels_higher.htm
17 http://www.salmonfarmers.org/media/01_08_04.htm
18 http://www.salmonfarmers.org/media/01_09_04_b.htm
19 http://www.fda.gov/fdac/features/2004/304_fish.html

Related links:

Fish Life Cycle
Species raised at the Finfish Hatchery
Table Top Recirculating System
Facilities overview

The MIT FinFish Hatchery
MIT Sea Grant's Aquaculture Curriculum On-line

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