4.1 General framework
4.2 Production technology
4.3 Social and economic factors
4. 4 Environmental impact
Most scientific research in aquaculture has followed a narrow disciplinary approach involving mainly the biological sciences. While this has contributed significantly to our understanding of the characteristics of individual species (e.g., their reproductive and nutritional requirements), rural aquaculture can be promoted only by a broad systems approach. Rural aquaculture is influenced by a hierarchy of systems ranging from micro to macro levels (Cai and Smit, 1994).
Social and economic aspects of aquaculture in particular have received much less attention than production aspects; this has constrained development through aquaculture (ICLARM/GTZ 1991; Ruddle 1993; Harrison et al., 1994). The same applies to agriculture, with the traditional agricultural science-led approach laying stress on production technology at the expense of social issues and environmental degradation. This calls for a new socio-ecological developmental paradigm centred on people’s needs and on environmentally friendly development (Grove and Edwards, 1993). The systems approach dates back about 50-60 years (Checkland, 1981), but it should be noted that small-scale farmers have always followed an holistic systems approach to maximise returns from resource-poor farms.
A systems framework comprising three interrelated aspects can facilitate our understanding of the factors involved in a sustainable aquaculture system (Figure 2) (AIT, 1994):
Fig. 2. The development of sustainable rural aquaculture systems involves consideration of production technology, social and economic aspects, and environmental aspects. (Source: AIT, 1994).
4.2.1 Cultured species
4.2.2 Culture facilities
4.2.3 Husbandry
4.2.4 Integrated agriculture-aquaculture
Production technology may be divided into three interrelated aspects: cultured species, culture facilities and husbandry (Figure 3). The cultured species determines the choice of facilities which in turn influences the choice of species. Culture facilities and species together determine husbandry.
Fig. 3. Production technology may be characterised by three major aspects: cultured species, culture facility, and husbandry (Source: AIT, 1994).
More than 200 species are farmed in both inland water and coastal areas. Major commodity groups relevant to rural aquaculture are finfish and molluscs (and to a lesser extent crustaceans such as prawns and shrimps) and aquatic macrophytes and seaweeds.
The species most important to rural aquaculture are herbivorous and omnivorous carps and tilapia; these dominate inland finfish production. Herbivorous milkfish also dominates coastal aquaculture; culture of tilapia in abandoned shrimp ponds has potential for coastal rural aquaculture.
Small-scale seaweed culture occurs in some countries but freshwater macrophytes which are a group of plants important in rural aquaculture are neglected by scientists and omitted from national and FAO statistics. Water spinach (Ipomoea aquatica) is an important vegetable in much of the humid tropics in Asia.
In contrast to agriculture and animal husbandry, most farmed aquatic organisms are genetically close to wild types i.e., they have been tamed but not domesticated genetically; these represent a huge underexploited potential.
A wide range of culture facilities are employed in rural aquaculture. Culture facilities which enclose aquatic animals part of the year include ricefields, irrigation ditches and ponds. These may be open to allow significant water exchange with the surrounding environment at least during the rainy season. Rural aquaculture is commonly conducted in ponds which are numerous in floodplains where they are dug to provide soil to raise the land level and minimise flooding of the house and its surroundings. Small ponds also provide water for household use, watering vegetables and livestock, and trapping wild fish. In many countries there has been a recent surge in pond construction, both in floodplains and in upland areas, mainly due to increasingly unreliability of water supply.
Pens are fenced and cages are boxed enclosures, which permit water exchange with the surrounding water body. Cages are usually, but not always, operated by wealthier farmers as water exchange usually requires costly and nutritionally complete formulated feed. The hapa (a nylon net enclosure used for nursing fish seed) has been successfully promoted to small-scale farmers (Little et al., 1991). Running water ponds or raceways and recirculation systems usually do not contribute to rural aquaculture.
A small fishpond in Son La province, Vietnam, also provides irrigation water for vegetables.
Grass carp are cultured in floating bamboo cages in Son La province, Vietnam.
Open culture facilities are employed for sedentary animals (such as molluscs), seaweeds and aquatic macrophytes. Hard natural substrates (such as rock, bamboo and wood) or artificial ones (concrete and rope) are used to culture sedentary animals and plants. These are placed on the bottom or are a means to suspend the cultured species in the water column using poles, frames, lines or rafts. Sedentary clams live in soft natural substrates such as sand and mud; they do not require substrates but may need to be contained by a fence.
Aquaculture may be divided into three sequential stages of husbandry: seed production, nursery and grow-out. Capture fisheries is still the means whereby seed (either broodstock, fry or fingerlings) of some species are obtained from natural waters. Such species do not have a closed life cycle as do farmed plants and animals. Modern seed production takes place in hatcheries. Early nursing (to produce fry) takes place in hatcheries but advanced nursing (which produce large fingerlings for grow-out) is more cost-effective if conducted as a separate enterprise. The grow-out of fingerlings, the final stage of culture, produces table fish.
The Chinese carp polyculture system and that for the Indian major carp, two of the world’s largest rural aquaculture systems, originally depended on wild seed from major rivers. Since the 1960s they have become almost totally dependent on hatchery-produced seed as induced spawning techniques involving hormone injection have been developed. Environmentally induced spawning of common carp (Cyprinus carpio) and silver barb or tawes (Puntius gonionotus) has a long history in East and Southeast Asia. Nevertheless, unavailability of suitable seed is a major constraint to rural aquaculture in much of Asia as well as Africa and Latin America. Farmers in Southeast Asia partly rely on local catch of carnivorous, swamp fish seed such as climbing perch (Anabas testudineus), snakehead (Channa striata) and walking catfish (Clarias batrachus or C. macrocephalus), but their culture has met with little success due to their feeding habit.
Traditional seed trading was initially limited by poor infrastructure and technology, seed being transported in open water containers, often on foot. The technology of transporting seed in oxygenated water in plastic bags has permitted the rapid development of highly commercialised seed distribution networks in countries with improved infrastructure, by motorbikes or trucks. Development projects normally attempt to improve seed availability by constructing large, technology-intensive, centralised hatcheries. Recent experience in Lao PDR through the AIT Outreach Programme indicates that seed production can be decentralised and production of seed can be successfully achieved at local level with a technologically minimalist approach.
The three sequential stages of husbandry (hatchery-based seed production, nursery and grow-out) are influenced by stocking and harvesting strategies, feed, water quality management, and disease prevention and therapy.
There are diverse stocking and harvesting strategies to better utilise water and space in the culture facilities and given feed to produce higher yields. Species may be stocked in monoculture or polyculture. Monoculture is commonly used for the intensive culture of a single, high-value species fed with formulated feed. In contrast, polyculture is more typical of rural aquaculture as two or more species are able to exploit the different feeding niches of extensive and semi-intensive systems in which natural food predominates. Stocking and harvesting may be either single or multiple, or a combination of the two but multiple stocking and multiple harvesting lead to the highest utilisation of available space and feed.
Natural food and supplementary feed mainly comprise the feed in rural aquaculture, in which extensive and semi-intensive scales of production predominate. In extensive systems, natural food is produced in situ, without nutritional inputs. In semi-intensive culture, by adding fertilisers and allowing the residual fertilisation of uneaten feed and fish faeces, growth of natural feed is accelerated. Natural food which is high in protein is mainly plankton and benthos, while supplementary food is added to complement high-protein natural food. Supplementary feed may thus comprise relatively low-cost, carbohydrate-rich substances such as brans and tubers. The fertilisers used range from organic (human, livestock or green manure) to inorganic chemical fertilisers. Examples of supplementary feed are agricultural by-products (brans, broken rice, waste vegetables; domestic waste food); green fodder which may be either wild or cultivated terrestrial vegetation such as grass, and wild or cultivated aquatic macrophytes such as duckweed, pond weed and water spinach; and agro-industrial by-products such as brans (where milling is conducted off-farm), broken rice and oil cakes. Formulated feed is also used as a supplementary feed to increase production when the growth rate of the biomass in the culture facility cannot be sustained by fertilisation alone (Diana et al., 1994).
Water quality management relates to the water inside the culture facilities although there may be considerable water exchange with that of the surrounding environment in pens and cages. Open water culture systems have a more intimate relationship with the environment from which they are inseparable. With increasing intensification of culture systems, dissolved oxygen may decrease and metabolic by-products such as ammonia may increase, threatening the growth and even survival of the stocked organisms. Rural aquaculture systems are rarely constrained by over-fertilisation and overfeeding but on better endowed farms high productivity levels can be sustained in static water ponds through balancing nutritional inputs and water quality without the need to resort to mechanical aeration characteristic of intensive aquaculture (Coleman and Edwards, 1987).
Disease is more prevalent in intensive systems, both in hatcheries and grow-out systems, in which high density of cultured organisms causes stress and increased susceptibility to disease. There are some exceptions, including the widespread outbreak of epizootic ulcerative syndrome (EUS) in Asia, the cause of which remains obscure; and the more recent outbreak of disease in extensive shrimp culture in Vietnam which may have been caused by infected juveniles from poorly managed hatcheries (Kwei Lin, personal communication). There have been major outbreaks of red spot disease in small-scale cage culture of grass carp in Northern Vietnam due to poor farming management practice. Disease adversely affects production but is usually related to poor farming management practice.
The major concern in rural aquaculture is how to introduce integrated agriculture-aquaculture successfully into the diverse small-scale farms in the developing world. The problem is widely recognised, but there is controversy about how to solve it.
Small-scale farms are typically nutrient-poor, rainfed, resource-poor and crop-dominated in developing countries, at least in the humid tropics where aquaculture has greatest potential. In Asia, wet rice cultivation is often the principal farm feature, although multiple cropping of other annual crops in and around the paddy fields and on adjacent dry lands exists. Another important component may be a mixed garden of fruits, vegetables and rootcrops. The proportion of wet rice, dryland crops and garden varies widely with agroecology, topography, farm size and population density. The availability of irrigation water greatly expands the opportunities for crop diversification. In Africa, the staple grain is usually maize, although there may be other cropping patterns.
Livestock are generally limited in small-scale agriculture since they depend on feeds from or near the farm. A few heads of buffalo or cattle are generally kept in Asia, mainly for draught; and some societies rear goats. Monogastrics, poultry such as chickens and ducks, and pigs traditionally scavenge for food, although in Asia they are fed rice-bran, a major crop by-product. Livestock are kept in pens or stalls in densely populated areas to prevent damage to crops. This facilitates their integration with fish.
Except in China and some parts of South and Southeast Asia, indigenous technical knowledge (ITK) in tropical inland aquaculture is limited. The major interactions between the on-farm sub-systems (Figure 4) have rarely included aquaculture. A pond may also be used to provide water for crops (rice nurseries and vegetables), livestock and domestic consumption. Pond mud may be removed as a crop fertiliser or soil conditioner. Livestock are fed on volunteer vegetation and invertebrates from on and around the farm. Human manure is an integral part of traditional farms, intentionally or unintentionally, in densely populated areas of Asia.
The poor resource base for aquaculture of most small-scale farms is illustrated by a baseline survey conducted by the AIT Aquaculture Outreach Project in Northeast Thailand. This revealed 41 different types of pond nutritional inputs available on-farm, but most farmers used only 2-4, mainly rice bran, buffalo or cow manure and waste vegetables (Table 2).
Table 2. Types and frequency of use of pond nutritional inputs reported by farmers, Udornthani, Thailand.
|
Type |
Percentage |
|
|
Rice and by-products |
|
|
|
|
Broken milled rice* |
8 |
|
Cooked rice |
13 |
|
|
Rice bran* |
66 |
|
|
Livestock manure |
|
|
|
|
Buffalo/cattle |
48 |
|
Pig |
7 |
|
|
Poultry |
5 |
|
|
Aquatic plants |
|
|
|
|
Duckweed |
11 |
|
Pond weed |
5 |
|
|
Water clover |
11 |
|
|
Terrestrial weeds |
17 |
|
|
Crop leaves |
|
|
|
|
Cassava |
11 |
|
Waste vegetables |
23 |
|
|
Termites |
25 |
|
|
Kitchen waste |
2 |
|
|
Crop by-products |
3 |
|
|
Agroindustrial by-products* |
1 |
|
|
Inorganic fertilisers* |
2 |
|
|
Formulated feed* |
4 |
|
In this context, production from average-sized ponds of 1,000 m2 was estimated at 40-70 kg (400-700 kg/ha/season), far below the 100 kg required for minimal household consumption. Similar low fish yields have been reported from Africa using on-farm inputs from resource-poor farms although they do contribute significantly to the household (ICLARM/GTZ, 1991; Pullin and Prein, 1995). Where ponds receive manure (human and livestock), brans and vegetation, such as in the more fertile Java (Indonesia) or the Red River delta of Vietnam, production may reach 5 tonnes/ha, providing annual consumption needs of 100 kg from a pond as small as 200 m2.
Scaled-down feedlot livestock-fish systems are commonly believed as the answer to rural aquaculture. In fact these systems are erroneously believed to be the major type of integrated farming involving fish. Such systems rarely survive the withdrawal of project support and are a classic example of mismatch of technology with the resource base as feedlot livestock are an intensive culture system (Figure 5). Poor farmers may only be able to run feedlot livestock-fish systems where they can market their livestock without competition from large-scale, vertically-integrated production (Edwards and Little, 1995). Systems based on poor quality on-farm inputs may also be unsustainable. Buffalo manure as a sole pond input is a poor fertiliser due to its low nutrient base and tannin content which stains water brown, and this inhibits light penetration (Edwards et al., 1994). Similar problems affect the use of manure of small ruminants like goats (Edwards and Little, 1995).
Both terrestrial and aquatic vegetation (usually wild, sometimes cultured) are commonly used as green manure and green fodder in small-scale aquaculture. This is particularly true for grass carp, one of the few herbivorous species that feeds voraciously on most green plant material. Most macrophyte feeders ingest only low-fibre plant matter. But a major constraint to the use of green plant matter is its low digestibility, which limits the amount that can be used without adversely affecting water quality. Further constraints to the use of some green fodders are nutritional imbalance, toxic components and high non-nutritional bulk (Yakupitiyage, 1993). Additional major constraints are the labour needed to transport bulky plant matter and the large area required to cultivate significant dry plant biomass, since vegetation is 80-90% water.
The poor quality and the high opportunity cost of on-farm inputs leads to consideration of off-farm inputs. Increased levels of off-farm inputs have improved the performance of small-scale agriculture (FAO, 1984). However, there has been a strange reluctance to recognise this in aquaculture. There are limits to the export of farm nutrients in the form of produce from the on-farm nutrient pool. Significant output requires a significant increase in nutrients for balance purposes, but this needs to be done in an environmentally sustainable way (Figure 6).
Fig. 7. Possible inorganic fertiliser uses and associated pathways on a crop/livestock/fish integrated farm.
Recommendations developed for the resource-poor context of Northeast Thailand include nursing fish fry in hapas by using off-farm nutritional inputs, a mixture of duck-feed concentrate and soft rice bran (Little et al., 1991). For grow-out, farmers should supplement a daily input of a minimum of a bucketful of fresh manure with a maximum of US$0.20 worth of urea daily, which farmers could afford. Significantly increased extrapolated yields of about 1.6 tonnes/ha or about three times the base production were obtained by this means and subsequent research showed that high fish yields can be obtained by use of inorganic fertilisers alone, provided there is sufficient carbon in the water to sustain phytoplankton production.
A balanced model using both on-farm and off-farm inputs for aquaculture may be needed for improved household welfare. Excessive use of agro-industrial inputs (inorganic fertilisers and formulated feed ingredients) is a major problem in both developed country and “green revolution” industrial agriculture and aquaculture but it hardly concerns most small-scale farmers in developing countries. This is illustrated by the contribution of aquaculture to farm household income in Northeast Thailand using three scenarios (Edwards et al., 1996). Baseline production before project intervention contributed an estimated 3% of total farm income (Table 3).
Table 3. Contribution of aquaculture to farm income with baseline fish production and recommended low and high input scenarios in Udornthani, Thailand.
|
|
Scenario |
|
|
|
Baseline |
Low-input |
High-input |
|
|
Total income |
4,360 |
4,652 |
4,957 |
|
Farm income |
2,440 |
2,732 |
3,235 |
|
Off-farm income |
1,920 |
1,920 |
1,920 |
|
Fish income |
71 |
178 |
482 |
|
Fish income (% total income) |
1.6 |
3.8 |
9.7 |
|
Fish income (% farm income) |
2.9 |
6.5 |
15.9 |
Table 4. Degree of intensification of fish production (extrapolated net fish yield, NFY) required to produce a minimum annual harvest of 100 kg fish. Modified from Edwards et al., (1996).
|
|
|
Extrapolated NFY (kg/ha/yr) |
|||||
|
100 |
500 |
1,000 |
2,000 |
5,000 |
10,000 |
||
|
Pond area (m2)
|
100 |
1 |
5 |
10 |
20 |
50 |
100 |
|
200 |
2 |
10 |
20 |
40 |
100 |
200 |
|
|
500 |
5 |
25 |
50 |
100 |
250 |
500 |
|
|
1,000 |
10 |
50 |
100 |
200 |
500 |
1,000 |
|
|
10,000 |
100 |
500 |
1,000 |
2,000 |
5,000 |
10,000 |
|
The broader question of interest that aquaculture farmers face concerns the most profitable way to apply fertiliser to the farm as a unit. Farmers are interested in total farm productivity and profitability, not just of the aquaculture sub-system. Should fertiliser be used in the pond or on the crops, and on what crops? Should the crops be consumed by man or fed to livestock or fish? Should human and livestock manure be used to fertilise crops or the pond? (Fig. 7). The most fruitful way to solve these questions and thus formulate guidelines is through bioeconomic modelling, which should involve more than integrated nutrient management, and over all factors of relevance to rural aquaculture.
4.3.1 Micro level
4.3.2 Macro level
Many of the issues discussed above involve socio-economic variables. Aquaculture development - promoted by fisheries biologists with vested interest in it (Ruddle, 1993) - has tended to ignore such factors.
Fig. 8. Social and economic aspects comprise macro and micro levels. Rural aquaculture may or may not be an appropriate farming system in a particular location (Source: AIT, 1994).
Social and economic factors may be considered at two levels, the micro level or community and farm household level, and the macro level or international, national and regional levels (Figure 8). The aquaculture production system may be relevant, either integrated with, or as an alternative enterprise to, other farming enterprises, or it may be socially and economically inappropriate. This simplified two-level hierarchy is useful because the micro level of production is under the control of the farmer while the macro level is the broader societal level which both influences and is affected by farming.
The relevance of the technical options for rural aquaculture depends fundamentally on social and economic factors at various levels. These determine the crucial issue of whether a household adopts aquaculture. It should be stressed here that the what (technology), who (target group) and why (role of aquaculture) must be addressed. Otherwise aquaculture, whether it be a farm household or community level production system, will not be adopted by new entrants at the production level.
Socio-economic status
The bottom line in adopting technical options for rural aquaculture is that they offer the farmer economic benefits. It is generally accepted that the behaviour of small-scale farmers in developing countries is “economic,” although their evaluation of economic benefits may not be short-term monetary gain, but the minimisation of risk. This seems to surprise some aquaculturists, although part of the problem is that insufficient studies on small scale have been carried out, as opposed to commercial aquaculture economics. The introduction of aquaculture has been suggested as a means to spread risk (Ruddle, 1993).
There are fundamental social, economic and technical differences between the semi-intensive systems appropriate for rural aquaculture and intensive systems. Semi-intensive systems use low-unit cost inputs but may be low or high cost depending on the intensity of fertiliser and/or supplementary feed input(s). In contrast, intensive systems are invariably high cost as they rely on high-unit cost, nutritionally complete, formulated feed. Semi-intensive systems are the choice for rural aquaculture because of the following:
Semi-intensive systems provide a mechanism for resource-poor farmers to gradually or incrementally intensify the production of their culture system as they gain confidence with aquaculture and increased cash flow.
The individual household’s resource base is crucial in determining whether or not aquaculture is viable, and with what type and scale of technology. Economists refer to the farm household’s resource base as on-farm “factors of production.” Normally these comprise land, labour and capital; but the first factor has to be widened to include water much more than in agriculture in aquaculture.
Despite the benefits to the rural poor provided by semi-intensive aquaculture systems, only the better-off apparently go into aquaculture. One reason could be the high cost of constructing the culture facilities, especially ponds. In Zomba district of southern Malawi, for example, landholdings of 76% of fishfarming households exceeded 2 ha, while 10.5% in the ‘below subsistence’ category had less than 0.8 ha. Unpublished data indicate that Northeast Thailand fishfarmers had distinctly larger holdings than their non-fishfarming neighbours. However, the investment constraint should not be overestimated as households commonly dig ponds for purposes other than aquaculture, ponds could already exist, or if newly constructed the investment may be shared. Younger and poorer families may inherit a pond. Finally, government and NGO projects frequently offer low-cost credit, or food-for-work to dig ponds e.g., in Cambodia. These mechanisms widen opportunities for the rural poor. Thus, the capital requirements for starting rural aquaculture may not be high. Pond excavation could be done manually. This could be a labour constraint, not of capital, and even may be reduced by progressive excavation over a number of years.
Thereafter seed and feed become the main costs; these constitute a relatively small investment. Even in Cambodia where seed are difficult to obtain, a small 200m2 pond may be stocked for US$5 which the better-off can afford or for which they borrow in the local financial market, especially from small-scale fry producers anxious to build up their sales. With some management and inputs from the farm, such an investment would have a return of $40-50 on a 40-kg production, a useful first step from which the farmer may consider further investment. Similar experiences have been reported from Ghana, Malawi and Zambia.
Access to land and labour
Access to land is necessary for most types of aquaculture. The exceptions are pen and cage culture which can be conducted in inland water bodies or brackishwater and certain types of coastal aquaculture which can be done offshore. Aquaculture may not be viable for the rural poor who do not have secure access to land, being either totally landless or holding land only in insecure tenancies. Some of the landless may have a home garden plot in which a pond can be dug, but the lack of mainplot agricultural holding limits their options. Subdivision of landholdings may also constrain aquaculture. In both Cambodia and Northern Vietnam, after the move to an individual land holding system, land was distributed in parcels as small as 500-800 m2 in different microecologies of the commune; this limits the area for a rice-fish culture system based on a single pond.
Apart from the question of access to land itself, land tenure is important. Lack of security of land tenure is a disincentive to long-term investment. Construction of a pond is thus unlikely to be attractive to tenant farmers or even those “land owners” without formal title deeds. In Bangladesh where multiple pond ownership is common, the large number of owners resulted in less intensive culture, and low annual production, at least amongst those with small ponds (Ahmed, 1992). The lack of understanding amongst shareholders ranked second to lack of capital amongst the farmers surveyed in terms of constraints to fish culture.
Labour may be a constraint to aquaculture. Production technologies utilising low-unit cost inputs may be based on on-farm or locally available inputs. Although these may be viewed as “free,” unless they are found in the immediate pond area, it takes time to gather them. This cost varies according to the opportunity cost of labour of the various household members. This depends on access to different, often off-farm opportunities and the relative openness of the village-level economy to the outside world e.g., in Thailand the opportunity cost of young active labour is close to the daily wage labour rate in the city of around US$5/day as Bangkok can be reached overnight by express bus from most parts of the countryside. Thus, it has proven difficult to develop a real poverty focus in promoting rural aquaculture in Northeast Thailand. Even low-cost recommendations have shown little sign of trickle-down to the poorest because the high opportunity cost of labour in farming in a rapidly developing economy has meant that the poorest groups seek the bulk of their livelihood off-farm. Low-input, low-output aquaculture can make little difference to the overall balance for the rural poor and it is only the rural middle-class, able to make their living on farm due to larger landholdings who view aquaculture as a useful addition to their agricultural system and seek to move towards higher production levels.
Fish culture requires relatively small but regular labour inputs for feeding (pond preparation and fish harvest may be labour-intensive). This contrasts with the typical labour regime of rainfed rice cultivation where there are major peaks of labour demand in transplanting and harvesting interspersed with periods of less activity. These intervening periods allow farmers to supplement their income with off-farm employment. Thus, aquaculture and complementary on-farm activities should offer sufficient return to make up for this opportunity or the household should have a large labour force. A survey revealed that Northeast Thailand fishfarming families had one extra labour unit than families not involved in aquaculture (AIT, unpublished data). Small-scale livestock, vegetable and fruit cultivation similarly require small but regular labour inputs such that returns in integrated aquaculture may be similar to that of off-farm employment. The problem lies in the early stages of development of such systems before elements like fruit trees and large livestock begin to offer returns.
Management of community facilities
If the investment in small ponds or paddy field aquaculture is out of reach of the rural poor, access to fish may only be available through public or communal water resources. However, the decline of the wild catch from these very resources stimulates aquaculture and their development usually depends on restocking, creating a ‘culture-based’ or ‘enhanced’ fishery. This is defined as aquaculture if it is managed either by the community, an individual or a corporate body. Unfortunately most attempts at restocking have been carried out by national fisheries agencies, implying state ownership of the resource. Authorities on the common property resource issue (Orstom 1990; Feeny 1994; Birkes 1994) note that this state ownership means in effect ‘open access’ and with it the dangers of unsustainable exploitation of the resource leading to the ‘tragedy of the commons.’ Arguably also, the lack of real property rights means that the fishing activity can no longer be defined as aquaculture.
In socio-economic terms, the major issue in culture-based fisheries concerns the nature of associated benefits and costs and their respective distribution. In larger water bodies such as new irrigation reservoirs, government agencies involved have been keen to recover the stocking costs. Commercial fisheries have thus been encouraged to the exclusion of small-scale fishermen living on the lakeshores and possibly resettled from reservoir-flooded lands. In smaller-scale enhanced fisheries, traditionally benefits were in the form of fish for consumption within the community, but there tends to be a shift towards a more commercial operation, partly to generate income for investment in rural village development. This trend may have its costs. While community-based management of culture-based fisheries is widely promoted, it should not be presumed that this leads to equitable distribution within the local population. Whether such management is in favour of the majority of the community or a few, depends a good deal on the power distribution at the local level. In Panama, strict rules governing the share of the harvest have been recorded (Molnar et al., 1985). In general, labour input records are kept to apportion the benefit, but a greater share is obtained by impoverished families. Similar arrangements persist in the Lao PDR. However, where strong, democratic community management does not exist, the result is expropriation of the resource
Socio-cultural factors
Social attitudes are a complex of important factors, the most important being the farmers’ goals and aspirations i.e., what they consider important in life. Modernisation and improved communications lead to rising aspirations, especially in relation to joining the market economy. A farming household may well be seeking opportunities to generate income but initial interest in aquaculture is likely to be low initially because of the almost universally low level of indigenous technical knowledge (ITK), especially in non-fish eating societies. However, Ruddle (1993) notes that in some communities in Malawi, social sanction on accumulation of wealth may also be a constraint.
Various social attitudes may be culture-specific rather than widespread. Some societies observe taboos which relate to fish specifically, but may affect aquaculture. Fish may not be consumed by vegetarians, and in some societies pregnant women are forbidden to eat fish. Buddhists in some countries oppose aquaculture because of a religious ban on killing animals. Many societies find it distasteful to recycle human or even animal manure.
Gender issues
Various farm-level factors have gender implications. These require studies to assess the effect of women’s position in the household economy and in society on the promotion of aquaculture, and on the possible impacts of aquaculture on women. Van den Mheen-Sluijer and Sen (1994) classified aquaculture according to the extent to which men and/or women are involved: dual systems in which husband and wife have separate ponds; male-dominated systems in which the wife provides a significant amount of labour; and female-dominated systems in which women are de jure or de facto head of household. Such a classification has some value. In the matrilineal, uxorilocal, kinship systems of parts of Africa, the rights of a woman (and her brothers) over land may in effect prevent their husbands from investing in aquaculture (Ruddle, 1993).
On the other hand, the effects of the ‘male-dominated’ system will depend on the wider context of gender relations within a particular society. If ‘male-dominated’ implies a particular balance of labour inputs in production, then the women’s position in the system may be underestimated. Women are frequently centrally involved in the sale and processing of aquatic products and as such are in control of the financial resources deriving from the activity.
What seems certain is that female-headed households face some problems in participating in aquaculture as a result of the heavy physical labour required in pond digging and harvesting. If this initial resource constraint can be overcome, the tendency for many small ponds to be located with the home garden system means that such women are often better able to participate in aquaculture than in several other farm activities.
Macro-economic policies
National development goals and policies often adversely influence rural aquaculture. Policies may favour export earnings rather than food security through aquaculture when a mixed strategy would be more desirable. Concern with food security in several Asian countries, however, adversely affected rural aquaculture as policy makers promoted rice at the expense of fish and even banned conversion of ricefields to fishponds. This may have had the opposite effect than intended because of foregoing the synergism in integrated systems in productivity, profitability and environmental sustainability, and underestimating the role of fish in food security.
Policy makers usually favour capital-intensive aquaculture which favours larger-scale farmers, partly because of a technocratic world view which equates development with increased productivity and economic efficiency. Policies also tend to favour short-term gain for special interest groups rather than long-term gain for society, particularly in relation to natural resources management. This may have an negative impact on rural development.
High levels of promotion and protection of industrial and urban sector issues indirectly affect agricultural and aquaculture sectors by keeping food prices low, taxing farmers, and reducing their incentives. Governments need to be concerned with both the cost and delivery of essential inputs to farmers as well as the prices they receive for their produce. Farmers will not modify their farms for aquaculture if powerful and pervasive economic forces are counterproductive. An important policy issue for the promotion of rural aquaculture on resource-poor farms concerns increased availability of inorganic fertilisers at prices which small-scale farmers can afford.
Availability of credit
In the traditional development paradigm, credit availability is a crucial input to the development of rural aquaculture. Credit provides funds for pond construction, seed and feed. However, there has been a major re-assessment of the demand for, and the supply of, rural credit over the past decade. The traditional view is questioned, in particular with regard to the role of informal rural financial markets. The need for external credit should not be discussed without reviewing such markets locally. In both Africa and Asia, relatively little capital may be required to start rural aquaculture with appropriate technologies. This calls into question the conventional view of small-scale farmers being unable to finance their own capital investments; as such, the need for rural credit evaporates. It is only when technology involves high levels of inputs that credit is required and only then if production involves a major scale-up from previous levels. The best strategy at the earliest stages of rural aquaculture development may be an incremental approach to investment which allows the farmer to expand the enterprise from the profits of his previous cycle. Rural credit has frequently put the farmer at risk by supporting enterprises which do not fit in the existing system. Credit, or free inputs, may be necessary if a farmer is asked to participate in on-farm technology trials. The crucial thing is facilitating the farmer’s investing in a well-tested technology which is within the limits of risk he can take. Where he perceives this to be available, he may be willing to invest his own limited capital.
Market and input supply
Farmers will not practice aquaculture unless it makes economic sense. This may depend on input supply (seed, fertiliser and feed) and market conditions at local and regional levels which determine the price of fish as well as the incentive to produce. Market conditions in turn are related to physical access in the form of infrastructure and economic access in terms of the purchasing power of consumers. Lack of and scattered demand for inputs such as seed result in high prices which may constrain the development of rural aquaculture. In South and Southeast Asia, private-sector fry traders have sprung up almost everywhere in response to demand e.g., in Vietnam itinerant traders transport fish by bicycle and motorcycle and in Thailand by truck.
Markets in rural aquaculture are not homogeneous. There are a variety of consumer groups, each with its own purchasing power and consumption preferences. Rural markets may differ from the typical urban physical structures; they may be more or less informal and include the rural consumer who buys fish at the pond bank. Markets may also be highly seasonal depending on both supply and demand. In the monsoonal climatic regimes of Asia, prices received for farmed fish may depend on the wild fish harvest i.e., market competition. Wild fish are not normally available from the end of the rice harvest to the early rainy season in rainfed areas of Northeast Thailand. As the trend is for a steady upward rise in prices throughout this period, farmers with good water supply may wish to hold on to their fish for as long as possible prior to sale. In Cambodia this premium is extraordinary as a result of large wild fish catch at the start of the reverse flow from the Great Lake at full moon in December and January. Even in outlying areas prices fall to about $0.03/kg but 2 months later rise to $1.25/kg (40 times higher), despite some of the rural population having stored fermented fish at peak periods. Certain fish are popular in certain seasons in relation to festivals e.g., large Chinese carps in China and Vietnam and at the rice harvest season in exchange for labour in Lao PDR.
Fish are highly perishable, especially in the tropics. As such, infrastructure facilities, marketing, and transportation besides ice are required. Alternatively, appropriate post-harvest technology are needed to preserve fish. Thailand is rather unique in Asia in terms of the quality of its road transport system even to the furthest corners of the country. This and refrigeration enable the rapid movement of fish to urban markets along the main highways. Both seafish and fish culture products in the Central Plain of the country are thus found in the major regional centres in the peripheries at relatively low prices. These include tilapia, catfish and snakehead which are transported in aluminium containers, as well as frozen blocks of Indo-Pacific mackerel. However, the rapid transportation system ends at the provinces and large urban districts, so that prices increase rapidly away from these centres with the highest fish prices at village level. While it is difficult for village fish producers to break into the urban market, local aquaculture produce is cutting into that market at village level.
The degree of industrial development influences rural aquaculture. Agro-industry may supply inputs and by-products (bran and oil cakes) as supplementary feed. But bran is also a traditional on-farm by-product of milling rice when it is done at the household level. Agro-industry may also supply products such as inorganic fertilisers and formulated feed ingredients which are required for intensified rural aquaculture. Industrial development also influences the extent to which farm household income can be diversified by off-farm employment as well as the provision of infrastructure and level of services, which includes extension.
However, competition from industrial agriculture and agroindustry adversely affects rural aquaculture by undermining small-scale livestock/fish integration. Traditional breeds of monogastric livestock (pigs and poultry) often prevail in less developed countries such as in Indochina where milling grain at the household level is widespread and feed concentrates are unavailable. Feedlot livestock may develop in periurban areas based on domestic food and agroindustrial by-products but rarely threatens rural production of livestock (and fish) due to limited feed. However, turn-key introduction of usually vertically integrated, feedlot livestock using improved breeds and formulated feeds competes with backyard pig and poultry, as shown in Thailand, reducing their economic viability.
4.4.1 Impact of the natural environment on aquaculture
4.4.2 Impact of man-made environmental changes on aquaculture
4.4.3 Impact of aquaculture on the environment
Environment is primarily external to the aquaculture culture facility. As with social and economic aspects, there is a spectrum of factors which range from macro- to micro-level.
Aquaculture systems are strongly influenced by natural environmental factors i.e., the ecological setting. This section covers conventional ‘environmental impact’ which may work in two ways: the impact of changes in the wider environment upon aquaculture; and the impact of aquaculture on the environment. In both directions these impacts may be either positive or negative (Figure 9).
Ecology (the study of the relationship between organisms and their environment) is a key factor in aquaculture because certain aquaculture facilities are located in natural or man-made ecosystems such as rivers, lakes, reservoirs and coastal areas. Furthermore “wild” organisms may influence the well being of cultured target organisms in various ways such as providing seed or feed affecting water quality, or threatening the cultured stock through disease, parasitism or predation. The term human ecology was coined in recognition of the fact that man is an integral part of, rather than above, ecology or nature. Agroecology is a more useful term as it relates specifically to the ecological aspects of agriculture, including agriculture. Agroecology like ecology can be viewed in a hierarchy from global, through regional and subregional levels, down to whole farm and enterprise.
CGIAR classifies developing-country agriculture at the macro level into zones based on climate by the CGIAR. At the subregional level topography also influences both agriculture and aquaculture. Aquaculture facilities at the farm level may comprise an enterprise within a larger, integrated agroecosystem such as various types of integrated agriculture/aquaculture systems (IAA). Alternatively, cages and pens in inland or coastal areas and open water mollusc or seaweed farms comprise agroecosystems within ecosystems.
Fig. 9. The two-way interaction between aquaculture and the environment involving numerous factors which range from positive to negative in their impact.
Macro level, climatic and geographic factors such as temperature, water and salinity strongly influence both agriculture and aquaculture. Aside from these a biotic factors, aquaculture is strongly influenced by a biotic factor, the availability of wild fish.
Finfish, the major commodity group in rural aquaculture, are usually considered as either coldwater or warmwater species. The commercially important salmonids (trout and salmon) can only be cultured in the tropics at high altitude but are of little relevance for rural aquaculture as they are raised intensively. A wide range of warmwater fish are suitable for warmwater aquaculture because of their herbivorous and omnivorous feeding habits. Warmwater fish may be either tropical species such as Indian major carps, silver barb and tilapias which cannot survive low temperature or temperate species such as Chinese carps and common carp which have been widely disseminated through tropical developing countries.
Aquaculture requires considerable water. Rainfall is sufficient in tropical equatorial regions for year-round culture but aquaculture may be constrained by both excess water or flooding during heavy rain and/or insufficient water during the dry season in other climatic zones, especially in monsoonal areas. Ponds are often constructed 2-3 m deep to store surplus water during the rainy season but high rates of evaporation and high seepage rates in porous soils may lead to total water loss and curtail culture. However water storage in on-farm reservoirs (OFRs) has been shown to be attractive economically for both agriculture and aquaculture in the Philippines where about 70% of OFR owners reported an annual profit of US$70 from reservoir-grown fish (Bhuiyan and Zeigler, 1994).
Local topographical conditions may produce a high water table which appears to be a significant factor in the development of IAA in some areas e.g., the lowlands of Mun river valley in Northeast Thailand. Groundwater may also offer potential where otherwise none might exist e.g., the culture of a double crop of high-value hybrid Clarias catfish in small ponds in Song Be province.
Water salinity can separate aquaculture into inland or freshwater where most rural aquaculture occurs, and coastal aquaculture. Coastal aquaculture includes culture in both full-strength seawater and in brackishwater. Most species live in constant level salinity (low salinity freshwater, or high salinity seawater) e.g., carps are cultivated in freshwater rather than in brackishwater with fluctuating salinity. Important brackishwater species are milkfish and increasingly tilapias, same of which can be cultured in lower salinities. Molluscs such as mussels and oysters tend to be brackishwater species. Seaweeds vary in their salinity tolerance with some species of agar producing Gracilaria tolerating brackishwater unlike carageenan producing Eucheuma.
A major biotic factor which influences rural aquaculture is the occurrence of wild fish which reduces farmer interest in adopting aquaculture. Recommendations for rural aquaculture were not attractive to farmers in the Mun river floodplain, unlike other areas of Northeast Thailand, because of the availability of significant amounts of wild fish in ricefields, especially the carnivorous snakehead (Channa striata). As these fish fetch high prices, the farmers regard them more as “produce” rather than as “predators” of seed stocked in aquaculture. Studies show that dramatic annual variations with significant differences in availability of the wild catch between zones at different distances from the river and from large natural water bodies such as swamps. This situation became clear after a study of fish consumption in Svay Rieng province, Cambodia, which revealed major differences in accessibility to wild fish in distances of only 10-15 km due to differences in microtopography and proximity to spawning grounds.
There is a general decline in wild fish in most areas, which leads farmers into aquaculture, but the process is far from simple. Wild rice-field fish production fluctuates considerably from year to year according to the amount and timing of the rainfall. Just as in rice cultivation, such instability is a problem for the farmer who needs a composite strategy to integrate fish culture with rice cultivation in his household livelihood system. Sadly, most proponents of rice-fish culture often fail to record the proportion of the wild fish catch.
With population growth and increasing pressures on the natural resource of wild fish in ricefields, changes occur in what was once regarded as a common property resource. Pakuthai and Karnonsri (1985) described a sequence of changes in the once famous Kula Rong Hai fishery in Northeast Thailand:
Where poor rainfall leads to several years of poor wild fish catch, the farmer may actually enter aquaculture, only to revert to the capture fishery system when improved rains materialise. Somewhere in this process, there is a cross-over when a farmer decides that wild fish yields are no longer worth his effort in catching fish and that investment in aquaculture is necessary to continue to benefit from fish. This is the classic issue of catch per unit effort applied to rural fisheries/aquaculture and is parallel to Boserup’s (1965) ‘virtue of necessity’ model of agricultural technical innovations.
Perhaps the classic issue in environmental effect on aquaculture is the construction of reservoirs for irrigation. Although the construction of water storage reservoirs usually impacts on the previous hydrological system and thus provokes dramatic and usually damaging changes in riverine fisheries, such effects may be compensated by the new potentials created for aquaculture, particularly in irrigated areas. This will only be true if fish culture competes with or complements other increased agricultural opportunities. Aquaculture may actually be constrained by increased pesticide use which generally accompanies the intensification of agriculture associated with improved water supply. Reservoirs may also be used for small-scale cage culture. Ultimately, stable water supply through irrigation schemes should lead to an increase in aquaculture. However, the overall impact of irrigation schemes on fish production to date has been negative because they reduce floodplain fisheries i.e., one staple, rice, is increased at the expense of another staple, fish.
Although construction of irrigation systems and OFRs should prove positive in promoting aquaculture, many man-made environmental changes have a negative impact on aquaculture. Fisheries are particularly vulnerable to pollution from urban areas, industry and intensive agriculture because water flows and therefore distributes pollutants widely. These are unlikely to affect most rural aquaculture which is rainfed-based and resource-poor, but may affect small-scale aquaculture in natural ecosystems such as rivers, large lakes, and coastal areas. Pollution may reduce growth or induce disease because of stress or even cause mortality. It may also contaminate produce with chemical residues or human pathogenic disease organisms.
Environmental degradation that impacts on both capture fisheries and rural aquaculture is deforestation through a variety of interlinked effects. Deforestation in inland flooded forests and coastal mangroves directly reduces capture fisheries by destroying spawning and nursing areas. This may indirectly affect rural aquaculture systems which depend on capture fisheries for seed e.g., extensive shrimp culture although declining capture fisheries does provide a stimulus for aquaculture development. However, deforestation increases siltation in water bodies and contributes to unstable water regimes which adversely affect rural aquaculture.
Aquaculture may exert a diverse range of impacts, both negative and positive, on the environment. Nevertheless, environmental impact assessment (EIA) should be carried out before the promotion of rural aquaculture (NORAD, 1992).
Eutrophication of water and sediments from discharge of aquaculture farm effluents is mainly associated with intensive aquaculture. The dangers of poor water quality are illustrated by complete anoxia in the water column of Lake Sampaloc in the Philippines through unregulated growth of cage culture (Santiago, 1994).
Extensive and semi-intensive culture facilities such as ricefields stocked with fish and small-scale fishponds are unlikely to have adverse environmental impact. Most small-scale farms are nutrient-poor. Even the use of off-farm inorganic fertilisers is unlikely to adversely affect the environment because most nutrients added to ponds are sequestered in mud. Furthermore the small size of ponds relative to total farm size in most multicommodity integrated farms means that the rate of fertiliser use on a total farm basis remains small (Edwards, 1993). Nevertheless, further studies are required because optimal pond fertilisation rates of 4 kg N and 1-2 kg P/ha/day are as high as those used on the most intensively fertilised field crops.
Widespread mangrove destruction occurred in the past due to the construction of extensive and semi-intensive fish and shrimp ponds (as well as salt pans) for rural aquaculture. Reduction of biodiversity due to introduction of exotic species or genetically modified organisms (GMOs) is of major concern (Pullin, 1994). Where widely distributed exotic species or GMOs are the basis for rural aquaculture, it is reasonable to develop or expand the culture of such species. Much rural aquaculture is based on exotic carps and tilapias. However, in countries with little or no aquaculture, indigenous species should be appraised for their consequences before exotics are introduced. The risks as well as the benefits of the transfer of exotic species and GMOs should be thoroughly appraised in advance.
The introduction of a fishpond on a typical crop-dominated small-scale farm can assist in agricultural diversification by providing a water source for crops and livestock besides fish culture i.e., to develop an integrated farming system. ICLARM has proposed that IAA be regarded as a means to manage the farm resources in toto i.e,. land, water, nutrients, biota, capital, and labour, and not only to increase fish production (Pullin and Prein, 1995). Integrated resource management (IRM) is a useful concept because it corresponds with the farmer’s desire to optimally utilise all the resources under his control. It should lead to increased environmental and social sustainability of the farm.
There is evidence that the introduction of aquaculture leads to reduced use of pesticides. When farmers stock fish in ricefields, they lower pesticide input such that the promotion of rural aquaculture also contributes to integrated pest management.
