Aquaculture Systems and Species1
(1)Simon Funge-Smith2 and Michael J. Phillips3
(1)FAO Regional Office for Asia and the Pacific,
Sustainable improvements in technological aspects of aquaculture will not be achieved unless they are accompanied by appropriate policies that address the social and economic environment within which the aquaculture system is placed. The development of such systems must lie within the context of environmentally sound regulatory frameworks (e.g. systems providing for monitoring and enforcement, and good governance)
In the 21st Century, water resources will be at a premium, with water shortages expected after 2015. With such a pressure on this vital resource for aquaculture, business-as-usual scenarios will no longer be possible. Competition for this resource will increase with drinking water shortage expected to affect large populations by 2025. This important constraint will have a major bearing on how aquaculture can and will develop in the new millennium, and appropriate technologies and farming systems will be required to address this issue.
Within the context of this paper, the essential elements of aquaculture incorporate: the care of aquatic stocks; requires confinement or site allocation; isolation to varying degrees of the farmed stock from the external environment; allows for various levels of internal control of the system; and requires some form of ownership or contractual arrangement to that effect.
Aquaculture systems must be considered in relation to natural resource systems and human development circumstances within which reside.
| This requires consideration of sustainability criteria, particularly
socio-economics and the wider interaction between aquaculture and other
processes and activities. These interactions have to be considered
both as aquacultures impact on other water and natural resource users,
and the impact of these on aquaculture.
Various aquatic organisms are grown in different ways including:
The phases of aquaculture include broodstock holding, hatchery production of seed, nursing systems, grow-out systems, and quarantining.
Together, this mix of intensity, culture systems, species, farming systems and different phase of culture create an extreme diverse collection of aquaculture systems and technologies.
|Although such techniques exist, their widespread dissemination
requires effective communication networks, reliable data on the merits and
drawbacks of the various approaches, and help in the decision-making process
through which people design their production systems.
|The use of rainwater storage ponds for aquaculture is another
effective use of the resource. The aquaculture production is a bonus. In
other small-scale systems the aquaculture component is the primary role,
with water storage as an accessory feature (for garden irrigation and watering
Integration of livestock and aquaculture is common in many countries although in the future, the use of livestock or industrial effluents (e.g. sewage, heated water, process water) for aquaculture may raise ethical issues (moral and public health), that will have to be addressed. Specific issues are those of disease transmission and accumulation of toxic compounds.
There are alternative sources of water readily available for aquaculture arising from, for example, floodwater control in Bangladesh, or use of saline ground or surface water not suitable for irrigation or municipal consumption. Saline waters and land cover large areas in several Asian countries, and provide significant opportunities for aquaculture.
The uses of recirculation vary widely, from broodstock management, hatchery and nursery rearing, grow-out and quarantine holding. It is likely that use of recirculation systems in intensified commercial aquaculture will increase in future. There are many possible solutions, adaptable to specific local situations.
The PAS system for American catfish is one example. It combines an extensive set of channels within the pond, for water treatment, with a highly intensive growth enclosure. The very slow circulation with low energy requirement provides good control of pond environmental processes whilst conserving water.
The recirculation of water is not necessarily highly intensive. Shrimp farmers in Thailand are successfully using closed pond systems for removing the requirement for water exchange making efficient use of brackishwater and helping to reduce risks of introduction of shrimp pathogens to the farming system.
Active suspension ponds, which reduce the requirement for water exchange, have been demonstrated for tilapia in Israel and the USA and in shrimp culture in Belize Hyper-intensive recirculation systems have many advantages.
| These include minimum water demand, limited space demand,
reduced water discharges, controlled conditions to optimise productivity,
tight control of feeding to maximise feed conversion efficiency, fairly
site-independent, exclusion of predators and climatic events, and necessarily
little use of chemicals. But such systems often involve high capital costs,
are more complex, and failures can result in serious crop loss. Such systems
place greater demands on management control, feed design, health management,
and demand professionalism in their use.
A well-designed recirculation system must be readily managed and competitive in terms of cost-efficiency, as such current applications are principally targeted at high value intensive aquaculture.
Hyper-intensive recirculation is currently particularly suited to Europe due to environmental pressures and the market for high value aquacultured species. As economic and resource conditions change in the future, alternative applications of recirculation are likely.
Technology issues in recirculation approaches:
There are a number of technology issues in recirculation technologies that include:
The design of feeds for recycling systems will: need to weigh conversion efficiency versus water treatment efficiency. Currently, feeds can be designed to facilitate the separation of faeces from the water and for reduction of nutrient leaching.
|Recirculation systems would be preferred for culture of exotics
species and GMOs, since escape to the wild can be more effectively controlled.
Intensification can cause stress by disrupting fish social structures but this varies with species some do better at high stock densities, and we need to know more about such behavioural characteristics. Fish may require pre-adaptation to the recirculation environment. Recirculation techniques can also be highly species-specific. Species that are currently difficult to culture can be selected to perform better in recirculation systems. As expected, strains that have been cultured and adapted to recirculation systems seem to perform best.
Welfare concerns as well as the desire for improved productivity will compel us to design systems to suit the needs of the cultured animal.
Water is not always the limiting factor that makes recirculation an attractive option in some cases it may be energy conservation such as heated hatchery and/or grow-out systems.
An important future environment for aquaculture expansion is the sea, particularly offshore waters. Currently coastal waters, bays and inlets etc. are utilized but the cost of open water development is currently prohibitive in most instances.
As we enter the new millennium, it is noticeable that the rate of increase in global aquaculture production is slowing. If this is due to production limitations, it suggests we are not using current technologies well, or alternatively those future increments will be more expensive to achieve. We therefore need fundamental innovations in aquaculture technology and it would also be useful to determine the potential performance of the available species, to help us optimise culture conditions.
The slowing of growth of aquaculture production is largely due to the effect of major current producers, as a result of saturation, problems with disease and environmental limitations. We should also take account of huge longer-term potential in South America and Africa, for which suitable technologies might already be available but have yet to be effectively transferred in a manner suitable to the prevailing local conditions.
| The immediate need in these regions is to address the socio-economic
barriers to aquaculture development.
Fish cage systems
The production of fish from cages is increasing globally. The technologies are now well developed in Europe, parts of South America (Chile in particular) and China. In SE Asia, cage farming of fish is advancing rapidly, in a wide range of species; the main limitations being the availability and high cost of feeds and shortage of seed. There is already considerable transboundary movement of fish seed and fingerlings in Asia, mainly for live fish markets in Hong Kong and China. Little is known of environmental impacts, although this trade is known to result in some destructive fishing techniques for fish fingerlings.
Each country has its own species, markets and issues that need to be addressed in the development of cage culture, but future expansion of this farming system is expected.
Inshore-nearshore cage farms:
Environmental impact minimization, or even positive impacts, can be achieved with inshore and nearshore cage farms. For example, combinations of fish cages with seaweed and shellfish culture can reduce nutrient and organic loading, combining cages and artificial reefs can contribute to stock enhancement and could have a long term potential for culture based fisheries.
There are a number of other technical issues that include:
Environmental management issues will be particularly important for the future development of cage culture. The issues to be addressed include:
2. Improved zoning and regulation and environmental management
Standards for materials
Other food sectors have strict regulations on the materials used: these are largely lacking for aquaculture. For example, plastics contain low molecular weight components, which may be a source of contamination. These include plasticizers, stabilizers, lubricants, coloring material, UV absorbers, antistatics, and flame retardants. Here there may be a need for standards for materials in recycling systems because those going into solution may contaminate the system and the product.
The quality and standards for feeds in aquaculture whilst relatively rigorous in some countries will need to become more rigorous in many countries in order to respond to export and market requirements.
There is a priority to close life cycles of species currently being grown out in aquaculture.
The requirements for sustainable aquaculture development will include both technological and people based approaches From this range of choices, the design and selection of appropriate culture systems can be made, which most effectively meets their needs and best fits the opportunities and constraints of the local environment.
Although such techniques exist, their widespread dissemination requires effective communication networks, reliable data on the merits and drawbacks of the various approaches, and help in the decision-making process through which people design their production systems.
We predict that access to supplies of suitable water (coastal, estuarine and particularly freshwater) will become increasingly problematic and will be the source of widespread competition. Aquaculture will have to adapt to this. Therefore, we must adopt or develop approaches which:
High-technology systems are often proposed to achieve the more efficient use of water (e.g. recirculation), or to avoid competition for water (e.g. offshore/oceanic farming). Since there is a relatively high risk of failure of such systems, we recommend:
Current recirculation systems are expensive and limited in their applications for most species. The functional interactions of their components are not well understood, and this makes it difficult to optimise systems for specific applications (e.g. quarantine, hatchery, grow-out).
There is an increasing need for environmental and system control as a result of intensification. We therefore recommend:
The composition of discharged water is an important factor in environmental sustainability. We recommend that research continues strongly in the areas of:
Both the need for efficient use of resources (especially water), and pressures exerted by the community, will require that farming systems are designed to meet the needs of the farmed animal. We therefore recommend more research on:
The ability of aquaculturists to meet their diverse needs, in the various environments used, depends on the diversity and adaptability of their system options.
One critical option is the cultured species. We therefore recommend that research on new species continues in a judicious and selective fashion, particularly in the following areas:
Aquaculture can be made more economically efficient through the development of additional products from the species grown. We recommend more research and development of fine chemical and pharmaceutical products from cultured organisms, including fish and invertebrates as well as algae and microorganisms.
Whilst further exploratory research must be done to achieve a quantum leap in aquaculture productivity, the effective dissemination of this knowledge is a key to future growth. Aquaculture of all types requires high levels of skill and professionalism, whether it is highly integrated with other users, or highly intensive and industrial, and generally because of its complex interactions with the local environment. We therefore recommend:
1 The views expressed in this manuscript are personal to the authors and do not necessarily reflect the views of NACA and FAO. This paper is a synthesis based on the presentation and discussions during the Conference session on aquaculture systems and technologies. The session panelists identified the principal issues that will confront aquaculture in the new millennium. These issues must be addressed if the application of aquaculture technologies and development of farming systems is to continue its current expansion.
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Aquaculture Systems and Species1
(1)Simon Funge-Smith2 and Michael J. Phillips3
(1)FAO Regional Office for Asia and the Pacific,
39 Phra Athit Road, Bangkok 10200, Thailand
(2)Network of Aquaculture Centres in Asia-Pacific (NACA),
Suraswadi Building, Department of Fisheries,
Kasetsart University Campus
Ladyao, Jatujak, Bangkok 10900, Thailand
Funge-Smith, S. Phillips, M.J. 2001. Aquaculture systems and species. In R.P. Subasinghe,
P. Bueno, M.J. Phillips, C. Hough, S.E. McGladdery & J.R. Arthur, eds. Aquaculture in the Third Millennium. Technical Proceedings of the Conference on Aquaculture in the Third Millennium, Bangkok, Thailand, 20-25 February 2000. pp. 129-135. NACA, Bangkok and FAO, Rome.