Everything about Aquaculture totally explained
Aquaculture is the farming of freshwater and saltwater organisms. Unlike
fishing, aquaculture, also known as
aquafarming, implies the cultivation of aquatic populations under controlled conditions.
Mariculture refers to aquaculture practiced in marine environments. Particular kinds of aquaculture include
algaculture (the production of
kelp/
seaweed and other
algae);
fish farming;
shrimp farming, shellfish farming, and the growing of
cultured pearls.
History
Aquaculture has been used in
China since circa
2500 BC. When the waters lowered after
river floods, some fishes, mainly
carp, were held in artificial
lakes. Their brood were later fed using
nymphs and
silkworm feces, while the fish themselves were eaten as a source of
protein. By a fortunate genetic mutation, this early domestication of
carp led to the development of
goldfish in the
Tang Dynasty.
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 often bred fish in ponds.
The practice of aquaculture gained prevalence in
Europe during the
Middle Ages, since fish were scarce and thus expensive. However, improvements in transportation during the 19th century made fish easily available and inexpensive, even in inland areas, causing a decline in the practice. The first North American fish hatchery was constructed on
Dildo Island, Newfoundland
Canada in 1889, it was the largest and most advanced in the world.
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)
Actually, there was keen interest in aquaculture in the United States as early as 1859 when Stephen Ainsworth of West Bloomfield, NY began his experiments with brook trout. By 1864 Seth Green had established a commercial fish hatching operation at Caledonia Springs, near Rochester, NY. By 1866, with the involvement of Dr. W. W. Fletcher of Concord Mass, artificial fish hatching operations were under way in both Canada and the United States.
In contrast to agriculture, the rise of aquaculture is a contemporary phenomenon. According to professor Carlos M. Duarte About 430 (97%) of the aquatic species presently in culture have been domesticated since the start of the 20th century, and an estimated 106 aquatic species have been domesticated over the past decade. The
domestication of an aquatic species typically involves about a decade of scientific research. Current success in the domestication of aquatic species results from the 20th century rise of knowledge on the basic
biology of aquatic species and the lessons learned from past success and failure. The stagnation in the world's
fisheries and overexploitation of 20 to 30% of marine fish species have provided additional impetus to domesticate marine species, just as overexploitation of land animals provided the impetus for the early domestication of land species
In the 1960s, the price of fish began to climb, as wild fish capture rates peaked and the human population continued to rise. Today, commercial aquaculture exists on an unprecedented, huge scale. In the 1980s, open-netcage salmon farming also expanded; this particular type of aquaculture technology remains 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.
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Economic role
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 worldwide aquaculture is very rapid (> 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 shrimp consumed is farmed and imported.
(External Link) In recent years salmon aquaculture has become a major export in southern
Chile, especially in
Puerto Montt and
Quellón, Chile's fastest-growing city.
Aquaculture is an especially important economic activity in China. Between 1980 and 1997, the Chinese Bureau of Fisheries reports, aquaculture harvests grew at an annual rate of 16.7 percent, jumping from 1.9 million to nearly 23 million tons. China now produces 70% of the world's farmed fish.
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Environmental impacts
The concentrated nature of aquaculture often leads to higher than normal levels of fish waste in the water. Fish waste is organic and composed of nutrients necessary in all components of aquatic food webs. In some instances such as nearshore, high-intensity operations, increased waste can adversely affect the environment by decreasing dissolved oxygen levels in the water column. Onshore recirculating aquaculture systems, facilities using polyculture techniques, and properly-sited facilities (for example offshore or areas with strong currents) are examples of ways to reduce or eliminate the negative environmental effects of fish waste.
Types of aquaculture
Algaculture
Algaculture is a form of aquaculture involving the farming of species of
algae. The majority of algae that are intentionally cultivated fall into the category of
microalgae, also referred to as
phytoplankton,
microphytes, or
planktonic algae.
Macroalgae, commonly know as
seaweed, also have many commercial and industrial uses, but due to their size and the specific requirements of the environment in which they need to grow, they don't lend themselves as readily to cultivation on a large scale as microalgae and are most often harvested wild from the ocean.
Fish farming
Fish farming is the principal form of aquaculture, while other methods may fall under
mariculture. It involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases juvenile fish into the wild for recreational
fishing or to supplement a species' natural numbers is generally referred to as a fish
hatchery. Fish species raised by fish farms include
salmon,
catfish,
tilapia,
cod,
carp,
trout and others.
Increasing demands on wild
fisheries by
commercial fishing operations have caused widespread
overfishing. Fish farming offers an alternative solution to the increasing
market demand for
fish and fish
protein.
Freshwater prawn farming
A freshwater prawn farm is an aquaculture business designed to raise and produce freshwater
prawn or
shrimp for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine
shrimp farming. Unique problems are introduced by the developmental life cycle of the main species (the
giant river prawn,
Macrobrachium rosenbergii).
The global annual production of freshwater prawns (excluding
crayfish and
crabs) in 2003 was about 280,000 tons, of which China produced some 180,000 tons, followed by India and Thailand with some 35,000 tons each. Additionally, China produced about 370,000 tons of
Chinese river crab (
Eriocheir sinensis).
Integrated multi-trophic aquaculture
Integrated Multi-Trophic Aquaculture (IMTA) is a practice in which the by-products (wastes) from one species are recycled to become inputs (
fertilizers,
food) for another. Fed aquaculture (for example
fish,
shrimp) is combined with inorganic extractive (for example
seaweed) and organic extractive (for example
shellfish) aquaculture to create balanced systems for environmental sustainability (biomitigation), economic stability (product diversification and risk reduction) and social acceptability (better management practices).
"Multi-Trophic" refers to the incorporation of
species from different
trophic or
nutritional levels in the same system. This is one potential distinction from the age-old practice of aquatic
polyculture, which could simply be the co-culture of different fish species from the same trophic level. In this case, these organisms may all share the same biological and chemical processes, with few
synergistic benefits, which could potentially lead to significant shifts in the
ecosystem. Some traditional polyculture systems may, in fact, incorporate a greater diversity of species, occupying several
niches, as extensive cultures (low intensity, low management) within the same pond. The "Integrated" in IMTA refers to the more intensive cultivation of the different species in proximity of each other, connected by nutrient and energy transfer through water, but not necessarily right at the same location.
Ideally, the biological and chemical processes in an IMTA system should balance. This is achieved through the appropriate selection and proportions of different species providing different ecosystem functions. The co-cultured species should be more than just
biofilters; they should also be harvestable crops of commercial value.
Sometimes the more general term "Integrated Aquaculture" is used to describe the integration of monocultures through water transfer between organisms.
For all intents and purposes however, the terms "IMTA" and "integrated aquaculture" differ primarily in their degree of descriptiveness. These terms are sometimes interchanged.
Aquaponics, fractionated aquaculture, IAAS (integrated agriculture-aquaculture systems), IPUAS (integrated peri-urban-aquaculture systems), and IFAS (integrated fisheries-aquaculture systems) may also be considered variations of the IMTA concept.
Mariculture
Mariculture is a specialized branch of aquaculture involving the cultivation of marine organisms for
food and other products in the open
ocean, an enclosed section of the ocean, or in tanks,
ponds or
raceways which are filled with
seawater. An example of the latter is the farming of
marine fish,
prawns, or
oysters in saltwater ponds. Non-food products produced by mariculture include:
fish meal,
nutrient agar,
jewelries (for example
cultured pearls), and
cosmetics.
Shrimp farming
A shrimp farm is an aquaculture business for the cultivation of marine
shrimp for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the
U.S.,
Japan and Western
Europe. The total global production of farmed shrimp reached more than 1.6 million
tonnes in 2003, representing a value of nearly 9,000 million
U.S. dollars. About 75% of farmed shrimp is produced in
Asia, in particular in
China and
Thailand. The other 25% is produced mainly in
Latin America, where
Brazil is the largest producer. The largest exporting nation is Thailand.
Shrimp farming has changed from traditional, small-scale businesses in
Southeast Asia into a global industry. Technological advances have led to growing shrimp at ever higher densities, and
broodstock is shipped world-wide. Virtually all farmed shrimp are
penaeids (for example, shrimp of the
family Penaeidae), and just two species of shrimp—the
Penaeus vannamei (Pacific white shrimp) and the
Penaeus monodon (giant tiger prawn)—account for roughly 80% of all farmed shrimp. These industrial
monocultures are very susceptible to
diseases, which have caused several regional wipe-outs of farm shrimp populations. Increasing
ecological problems, repeated disease outbreaks, and pressure and criticism from both
NGOs and consumer countries led to changes in the industry in the late 1990s and generally stronger regulation by governments. In 1999, a program aimed at developing and promoting more
sustainable farming practices was initiated, including governmental bodies, industry representatives, and environmental organizations.
Types of fish in aquaculture
Further Information
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