1-Introduction:
The Japanese Resource Council, Science and Technology Agency as under
have defined aquaculture [1]:
“Aquaculture is an industrial process of raising aquatic organisms up to final
commercial production within properly partitioned aquatic areas, controlling the
environmental factors and administering the life history of the organism positively
and it has to be considered as an independent industry from the fisheries
hitherto.”
The global production of food fish from aquaculture, including reached 52.5
million tones in 2008 that covers about 45.7 of world’s fish production in 2008.
China is known as the world’s largest aquaculture [1].
There are five main ways in which fish can be farmed:
1. Cages which are categorized as fixed, floating, submersible, and submerged.
2. Closed water systems.
3. Pond (usually counted for less than one hectare).
4. Raceways.
5. Inland aquaculture farms.
2-Pros and Cons of Aquaculture
The pros for aquaculture could be described as:
- Creation of thousands of jobs and millions of dollars in income [2].
- Provide substantial socio-economic contribution to many coastal and
rural communities where aquaculture takes place [2].
- Supplies almost half of global demand for fish and seafood [2,3].
- Supplies a fresh, reliable, year-round source of protein [2].
- Reduces fishing pressure on certain species, thus helping the life cycle
of wild lives [3].
On the other hand, the cons could be summarized as:
- Nutrition Enrichment: including nutrient and organic matter
(eutrophication, sedimentation and effects on the food web) [2,4].
- Chemical pollution: including pesticides, drugs and antifoulants (There is
relatively less health issue knowledge such as ecological effects of
chemotherapeutics on non-target species. Also accumulation of
antibiotics in sediments may interfere with bacterial communities and
affect mineralization of organic wastes [5]. The evolution of drug resistant
strains of pathogenic bacteria is perhaps the most important implication
of antibiotic use in aquaculture. Resistance to antibiotics is present in
bacterial populations naturally [6,7,8]).
- Interactions between farmed and wild species; including disease
transfer and genetic & ecological effects (Farmed fish could escape and
establish in the wild, thus harming wild stocks by competing for habitat
and food or by producing an unnatural hybrid species. Additionally the
other species that rely on those farmed fish get attracted to the farm and
get trapped on the barriers that farmers use for separation) [2].
However, since different type of aquaculture has different impacts on
environment, we can take a closer look at their impacts separately. Based on
World Wild Life (WWL) report that has partnered with Food and Agriculture
Organization (FAO) in 1999, we can categorize the aquaculture to the groups
below [9].
- Shrimp:
- Approximately 5 million metric tons of shrimp produced annually.
- Most shrimp production is in China, followed by Thailand, Indonesia,
India, Vietnam, Brazil, Ecuador and Bangladesh.
- The major import of shrimp is to the United States, European Union and
Japan.
The key environmental and social issues related to shrimp aquaculture are:
- Farm design: Ecologically sensitive habitat.
- Water use/pollution: Salinization happens during aquaculture of shrimp
that can get into the groundwater. Also organic waste, harsh chemicals
and antibiotics used from shrimp farms are water pollutants.
- Feed management: Wild stocks of fish can be depleted for use in
formulated feeds for shrimp production
- Broodstock: There are biodiversity issues related to the collection of wild
brood and seed
- Pathogens: Pathogens can result into major shrimp disease outbreaks
and consequently significant economic losses in producing countries
- Socioeconomic issues: Jobs are really sensitive to the outbreaks and
fewer wild caught shrimp to harvest
- Salmon:
- One of the most popular fish species in the United States, Europe and
Japan.
- Approximately 60 percent (1.26 million metric tons) of the world's salmon
comes from fish farms.
- Norway and Chile are the major producers that supply close to two-thirds
of the world's farmed salmon due to the geographical conditions. Other
significant producers are Chilie, the United Kingdom, and Canada.
- Farmed salmon are most commonly grown in cages or pens in semisheltered
coastal areas, such as bays or sea lochs.
The key environmental and social issues related to salmon aquaculture
are:
- Benthic impacts: Chemicals and excess nutrients from food and feces
associated with salmon farms can disturb the flora and fauna on the ocean
bottom (benthos)
- Chemical inputs: Excessive use of antibiotics, anti foulants, and
pesticides has been used that can cause many consequences for marine
organisms and human health.
- Disease/parasites: Sensitivity to the viruses and parasites transferred
between farmed and wild fish and among farms.
- Escapes: Escaped farmed salmon can compete with wild fish and
interbreed with local wild stocks of the same population, altering the
overall pool of genetic diversity.
- Feed: In order to supply the fishmeal and fishoil, farmers are very
dependent on other wild fish that cause a lot of pressure on fishing
resources. Fish caught to make fishmeal and oil currently represent onethird
of the global fish harvest.
- Nutrient loading and carrying capacity: Excess food and fish cause an
increase in the levels of nutrients in the water that can result in
eutrophication.
- Social issues: Salmon farming produce a large number of jobs.
Additionally, conflicts can arise among users of the shared coastal
environment.
- Biavalve
- Filter-feeding bivalves (clams, mussels, scallops and oysters) make up
approximately one-quarter of the world's aquaculture production.
- China is the major producer with more than 80 percent of the world’s
farmed bivalve shellfish production. Other important producer countries
are Japan, the United States, France, Thailand, Spain, New Zealand, and
Italy.
- Unlike most finfish and crustaceans, bivalves feed on naturally occurring
phytoplankton at the base of the food chain that eliminates the need for
external feed inputs.
- Also, these shellfish often improve water quality by filtering sediment and
excess nutrients.
- Shellfish can create a complex three-dimensional habitat that can be
beneficial because it often is colonized by vertebrate and invertebrate
fauna.
The key environmental and social issues related to bivalve production are:
- Ecosystem integrity: Habitat interactions and ecological community
structure modifications
Genetics: Escaping and inbreeding can cause the gene transfer to wild
populations
- Disease: Pathogens are issue and the use of chemicals for preventing
and controlling diseases will cause pollution.
- Farm maintenance: Biavalve farms need more management regarding to
disposal of debris, chemicals, and organic waste; processing of wastes;
treatment of effluent; and maintenance of equipment.
- Tilapia:
- Approximately 2.3 million metric tons of tilapia is produced annually which
73 percent of it is farmed.
- Most of the tilapia is produced in China, followed by Egypt, Indonesia,
Thailand and the Philippines.
- Most tilapia is imported to the United States, the European Union and
Japan.
The main impacts related to tilapia aquaculture are:
- Compromise of ecological integrity of aquaculture facilities:
Overstocking, stress and other factors can make farmed tilapia
susceptible to viruses and diseases.
- Pollution from inputs used at aquaculture facilities: Feed and fertilizer
used in excess at tilapia aquaculture facilities can pollute the water mostly
by eutrophication.
- Invasive species: Nonnative tilapia that escape can compete with native
fish species and change the genetic makeup and diversity of species.
- Socioeconomic impacts: Aquaculture can conflict with other uses of an
area or resource, such as the use of water bodies for recreation and
reliance on landscapes for scenic vistas.
- Pangasius
- The farming of pangasius - mainly tra (Pangasianodon hypophthalmus)
and basa (Pangasius bocourti) - is one of the fastest growing types of
aquaculture in the world.
- Vietnam produces 90 percent of Pangasius farming
- European Union countries are the major export market, with a share of 35
percent.
The main impacts related to pangasius aquaculture are:
- Legal: Farms are sometimes constructed and/or operated outside the
legal framework for addressing environmental, social and food safety
issues of relevance to the area where the farming occurs
- Land use and water use: other sensitive habitat that shares the water
can be destroyed.
- Water pollution and waste management: Excess waste can pollute the
water and negatively affect plant and animal habitat
- Genetics and biodiversity: escaping from aquaculture will cause
competing with wild fish and affecting ecosystems, especially in areas
where pangasius is not yet established
- Feed management: Use of fishmeal, fish oil and trash-fish as pangasius
feed is resulting in depletion of food sources that other fish rely on.
- Health management, veterinary medicines and chemicals: Pangasius
farms may cause in health problem on other species. Also, the
inappropriate use of veterinary medicines and chemicals can have
unintended consequences on the environment and human health, such
as antibiotic resistance and unsafe products.
- Abalone
- Abalone is a type of mollusc.
- Abalone farming is supplying about 70 percent of global use.
- China produces more than 80 percent of Abalone need which most of it is
consumed domestically. The other producers areSouth Korea, South
Africa, Taiwan, Australia, Chile and the United States.
Main impacts of abalone aquaculture on environment are:
- Farm siting/infrastructure: Aesthetics, noise, odor and dust; habitat
destruction and rehabilitation.
- Energy use: Excess electricity used of large-scale farms has become a
big concern.
- Feed inputs: Unsustainable wild seaweed harvest; fishmeal and fish oil
content in manufactured feed.
- Biosecurity: Transfer of diseases to and from the wild, within the wild and
within aquaculture systems; pathogen amplification.
- Ecosystem effects: Benthic impacts, such as sedimentation and erosion;
eutrophication; habitat destruction; and wildlife interactions
- Waste management: Effluents such as nutrients, sediment and
chemicals, biological waste, and solid wastes
- Fresh water trout:
- Most freshwater-farmed trout is rainbow trout.
- The main rainbow trout producing countries are Iran, France, Italy,
Denmark, the United States and Spain. These same countries are where
most trout is consumed.
- Different systems can be used in farming of this type such as cages in
lakes, flow-through systems, ponds, and recalculating systems.
Main impacts of trout aquaculture on environment are:
- Water use: The excess amount of water is needed to be used wich will
affect water resource.
- Escapees: Trout that escape from farms can compete with wild fish for
habitat and breeding grounds.
- Discharges: Waste produced in farming can pollute the water.
- Fish health/welfare and disease transfer: If not managed well, trout
production can expose fish to stress and diseases that can impact both
farmed and wild stocks.
- Feed ingredients: The feed used in trout production includes a high level
of wild caught fish, some from fisheries that are not environmentally
sustainable.
- Energy efficiency and carbon footprint: The energy consumption is
large in the farms and consequently will cause in high carbon.
- Predator control: Birds and other predators can consume considerable
volumes of fish from the farms and cause serious economic losses to the
producers.
- Seriola and cobia
- Cobia and Seriola are also known as amberjack, yellowtail kampachi,
hamachi and hiramasa.
- Japan and Australia are the major producer of Seriola.
- Seriola and cobia are usually produced in cages – some close to land and
some in the open ocean.
3-Regulation
It seems that aquaculture should be governed at in the international level. It has
been proven that environmental impact studies and life cycle assessments
which were done only nationally have failed at in the international levels. One
national jurisdiction might have regulation that would follow the environmental
limit lines for that nation, but due to the fact that the sources for fishing are in
common use (except for the species that are in local rivers and lakes which still
would affect the life cycle of related waters) and also due to the fact that the
import and export of fish and seafood happens globally (which may result in
spreading a disease or other health issues globally), it should be a minimum
international guideline that develops sustainable practices.
The need of international regulation resulted in partnering of WWF partnered with
FAO, the World Bank and the Network of Aquaculture Centers of Asia Pacific to
create the Shrimp Aquaculture and the Environment Consortium In 1999. The
United Nations Environmental Program has since joined the as well. In 2006,
after the completion of more than 140 meetings with more than 8,000 people and
the publication of 40 case studies by 120 researchers, the FAO’s Committee on
Fisheries adopted the consortium’s International Principles for Responsible
Shrimp Farming. WWF held eight roundtables known as Aquaculture Dialogues
with participation of more than 2000 people -- farmers, conservationists,
academics, government officials and others that started in 2004. As the result of
these discussions, standards for minimizing the major negative environmental
and social impacts for tilapia, abalone, clams, mussels, scallops, oysters and
Pangasius were established. These efforts are still continuing and it is expected
that in 2011 the standards for freshwater trout, salmon, shrimp, Seriola and cobia
be finalized [9].
References:
[1] FAO official website
(http://www.fao.org/docrep/field/003/AC169E/AC169E00.htm#ch1.)
[2] www.dfo-mpo.gc.ca
[3] http://www.aquaculturepro.com/
[4] B.T. Hargrave, Marine Environmental Sciences, Fisheries and Oceans
Canada Bedford Institute of Oceanography, Dartmouth, Nova Scotia
[5] Stewart, J.E. 1994. Aquaculture in Atlantic Canada and the research
requirements related to environmental interactions with finfish culture, p. 1-18.
In A. Ervik, P. Kupka Hansen and V. Wennevik [eds.]. Proceedings of the
Canada- Norway Workshop on Environmental Impacts of Aquaculture. Fisken
Havet 13.
[6] McPhearson, R M., A. DePaola, S.R. Zwyno, M.L. Motes and A.M. Guarino.
1991. Antibiotic resistance in Gram-negative bacteria from cultured catfish and
aquaculture ponds. Aquaculture 99: 203-211.
[7] Johnson, R. and J. Adams. 1992. The ecology and evolution of tetracycline
resistance. Trends in Ecology and Evolution 7: 295-299.
[8] Spanggaard, B., F.G.L. Jorgensen and H.H. Huss. 1993. Antibiotic
resistance in bacteria isolated from three freshwater farms and an unpolluted
stream in Denmark. Aquaculture 115: 195-207.
[9] WWL official website (
http://www.worldwildlife.org/what/globalmarkets/aquaculture/aquaculturedialog
ues.html)
