Abstract:
75 Contrasting strategies for inland fish and livestock production in Asia D.C. Little and P. Edwards Agricultural and Aquatic Systems Program, School of Environment, Resources and Development Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani, 12120, Thailand Summary The development of inland fish and livestock production in Asia has been linked to the need for animal protein by the increasing population of the region. Reliable supplies of stock underpin both fish and livestock farming. The production and dissemination of fish seed, typically of wild or undomesticated strains, has been critical to the emergence of sustainable aquaculture. The source, form and application of nutrients used in production identify the level of intensity for both fish and livestock culture. Extensive systems, with only naturally occurring nutrients are still viable where the opportunity cost of land is low, but semi-intensive systems receiving supplementary fertilisers and/or feeds produce most farmed fish and livestock inAsia. Intensive systems, using complete formulated rations in feedlots, are most common for pigs and poultry and carnivorous fish and their development is linked to the dominance of agribusiness. Pest and hygiene management are key components of both fish and livestock production; traditional and modem practices share similar values and, increasingly, the same medicaments. Risks to public health through transfer of diseases, residues from treatment and direct pollution exist, although these may be independent of intensification or integration of livestock and fish culture. The aquatic environment has constrained both effective control of pathogens and the development of aquaculture systems. Livestock and fish production occurs in a range of culture environments from those similar to natural systems to highly modified, densely stocked systems. The economics of intensive systems, particularly the cost of feeds, has led to the integration of intensive livestock or fish culture with semi-intensive fish culture in some areas of Asia. Introduction of new species, both livestock and fish, has risks for both future food production and the wider environment. However, a major trend is the expected increase in the production of a fish exotic to the region, the tilapia, in both semi-intensive and intensive systems for both local and export markets. Introduction Aquaculture is now developing into a food production system of major importance in parts of Asia. Many aquatic products that include algae, molluscs, crustaceans and fin fish are farmed but the latter dominate inland production. Aquaculture, including stocking and harvesting of communal water resources, accounts for an ever increasing proportion of the fish that people consume in the region. Although there are great differences within Asia, more fish is consumed per capita in the region than in Africa or Latin America (Laureti, 1996). Aquatic products from inland sources are most important in the so -called `rice -fish societies' of the region, in which the staple diet of rural people is rice and vegetables complemented with fish (Laureti, 1996). In contrast, food products derived from livestock comprise a smaller proportion of the diets of such people. Providing draft power is the main role of large ruminants, but asset accumulation and a source of fertiliser are also important reasons why pigs and poultry are raised in small numbers (McDowell, 1980). The key importance of fish in the diet has provided a stimulus for the development of aquaculture, which is neither traditional nor widespread in most of Asia. Natural stocks of aquatic products, including frogs, crabs and various insects were, until recently, adequate for subsistence purposes in all but the most densely settled rural areas of Asia. Undeveloped markets for these highly perishable products probably also constrained commercialisation. Small game, both birds and mammals also complement subsistence ricegrowing close to forest areas (Srikosamatara et al. 1992). The need to intensify either fish or livestock was therefore not considered by the majority of rural dwellers until quite recently. The rise in importance of both aquaculture and intensive production of monogastric livestock is driven by two major forces: overexploitation of natural stocks and increased human population. The latter has also led to modification or destruction of habitat and increased demand for food. There is a rising demand for Recent Advances in Animal Nutrition in Australia 7997 University of New England, Armidale NSW 2357, Australia 76 Litt/e, D.C. and Edwards, I? farmed products by both rural and urban consumers. As most Asians will be urbanised by 2000 (Simpson, 1979) demand will increase further. This article explores some of the basic similarities and differences in the development of fish culture and livestock farming in the region. Differences in the nature of the aquatic environment, and how they affect development of farming aquatic, compared to terrestrial animals, are considered. Concepts and definitions are followed by the historical development of traditional culture systems. Then the essential characteristics of intensification that both aquaculture and livestock production share are outlined, i. e., the development and use of germplasm, changes in the source, form and application of nutrients, the management of pests and hygiene, and system development. The importance and increasing scarcity of water means that aquatic-based food production is intimately linked with surrounding farming and livelihood systems; aquaculture has the potential both to pollute and to become sustainably integrated and these issues are also explored. Finally, we speculate on future developments in fish culture in the region and a comparison with the recent history and trends for livestock is useful to predict the species and systems that will supply the region's fish into the next millennium. Concepts and definitions Comparison of livestock and fish production is facilitated by a schema (Figure 1) for the probable evolution of farming systems from traditional, cropdominated systems (Settled Agricultural Phase I), through mixed farming in which the importance of livestock was enhanced through their integration with crops (Settled Agriculture Phase II), to industrial agriculture characterised by monoculture (Settled Agriculture Phase III, Edwards et al. 1988). The latter system includes the `green revolution' of developing countries (WCED, 1987). Livestock and fish production in systems are generally extensive within the first category, receiving no or few nutrient inputs above those available naturally: they are semi-intensive in Phase II, receiving nutrient supplements as fertilisers or feeds; or they are complete feeding systems (Phase III). The `green revolution' in which new genotypes and agro-chemicals boosted the yields of staple cereals and pulses, has no direct parallel in livestock or fish production, although it has supported the development of both semi-intensive and intensive livestock and fish production. Polycultures, systems in which more than one product is grown in the same unit (field or pond), are suitable for both extensive and semi-intensive systems dependent mainly on a variety of natural foods, in contrast to single species monocultures typical of intensive systems. However, the three-dimensional aquatic environment (water column, sediments and margins) generally has a larger range of ecological and production niches than the terrestrial environment. Feeding habits are similarly more diverse. The carnivorous nature of some popular wild and cultured fish species has no direct comparison with livestock which are omnivorous or herbivorous (Tacon, 1996). The use of animal-protein supplements is common to more intensive forms of both aquaculture and livestock however. Social and economic aspects of people's relationships to livestock and fish also show similarities across the continuum. From being a minor but important part of a variable complex of activities in Phase I, livestock and fish farming become highly specialised at the level of industrial farming. The knowledge required, and the extent and type of resources needed (land, water, labour) change with intensification as do the purpose and fate of the outputs which increasingly develop from a subsistence to a cash orientation, and from local to distant markets. Figure 1 Schema showing the evolution of farming systems for livestock and fish inland fish and livestock producton in Asia 77 Historical development of tropical aquaculture Aquaculture has evolved in Asia as wild fish stocks have become insufficient to meet needs. Traditional systems therefore first developed in the densely populated, flood plain areas of China and the Indian Sub Continent where demand was high and wild fish seed for stocking was available from major rivers. Herbivorous and omnivorous species that feed low in the food chain, Chinese and Indian major carps, characterise culture in those two regions. Aquaculture is more recent in other parts of Asia and has been introduced Tom China (Edwards et al. 1988, 1997). Management of Indian major carps was limited to stocking and harvesting of wild seed (Tripathi and Ranadir, 1982), but complex systems in which fish culture was well integrated within the farm characterise Chinese aquaculture systems. This was facilitated by the complementary `grazing' feeding ecology of the riverine carps typically stocked in static water ponds and rice fields. Limited amounts of human and livestock manure were supplemented by grasses and other fodder that the dominant grass carp (Ctenopharyngodon idella) consumed; their inefficient digestion resulted in fish manure being probably the most important source of nutrients for the food web through production of planktonic and benthic organisms which supported the growth of different fish species (Little and Edwards, 1994). Fish such as the silver and bighead carps in turn promoted recycling of nutrients within the pond (Milstein, 1992). Many of the native fish most prized in Asia are carnivorous and a range of species is now cultured. Traditionally, however, these depended on the availability of small wild fish from artisanal fishing, rather than being integrated within rice-based farming systems. Artisanal cage culture of high-value carnivorous fish such as pangasid catfish and snakehead is found in Cambodia and Vietnam but its extent has been limited by the feed resource base, which is both seasonal and competes directly with human consumption (Chhouk, 1996). Overall production of carnivorous fish is thus far lower than from fish raised in semi-intensive systems. Traditional systems encompass the full range of intensification, i e. extensive (unfertilised, traditional Indian major carp culture), semi-intensive (Chinese carp polycultures) to intensive (cage culture of carnivorous fish). There are similarities to the evolution of livestock fming systems with extensive pastoralism comparable to extensive aquaculture, and mixed farming or settled Agricultural II comparable to the integrated farming of Chinese carp polycultures. Traditional-style intensive cage culture is most analogous to `cut and carry' feedlot systems used to intensify livestock production in which feeds were collected in and around the farm prior to the emergence of modem feedlots. Fishers collected and used trash fish while animal husbandry used vegetable fodder for ruminants. Major changes have occurred in both livestock and aquaculture over the last half-century as the era of settled Agricultural Phase III, or industrial monoculture has dawned. However, the dominance of vertically integrated agribusiness is highly variable in Asia. Modem poultry is dominated by such concerns in many countries, swine to a lesser extent; but ruminant and fish production are largely still in the hands of small entrepreneurs and farmers. Intensification of crop production, the so-called green revolution, has had both direct and indirect effects on livestock and fish production. Whereas fossil fuel-based mechanisation and use of agro-chemicals undermines the traditional position of livestock and fish on the farm, the food surpluses created can support intensified fanning of both. Feedlots produce large amounts of animal protein in small areas through the feeding of diets mainly composed of food grains and their by-products. Four major aspects of intensification, discussed below, are common to livestock and fish production: 0 a 0 germpl.asm development nutrient source, form and application pest and hygiene management system development 0 Germplasm development-the introduction of fish seed production technologies and new species In contrast to livestock production which is dependent on a handful of domesticated species (although a plethora of strains), aquaculture in Asia is characterised by a large number of cultured species. Most fish species have been cultured only relatively recently, and almost all are essentially `unimproved, wild strains. This is a fundamental difference between livestock and fish production reflecting the pioneer status of aquaculture. Furthermore, Asia has a rich natural fish fauna with a huge array of potential species for culture. Again in contrast to livestock, a major constraint to the spread of aquaculture from its origins in the flood plains of Asia is that most commonly cultured fish species do not breed spontaneously under culture conditions. An exception is the longest and most widespread species cultured, common carp (Cyprinus carpio), that will spawn with simple environmental stimulation. This trait, together with its generally highly favourable cultural characteristics, have allowed this species to be cultured in a wide range of traditional and modern systems throughout Asia. Similar advantages have made its close relative, the ubiquitous Koi into a global ornamental. The development and dissemination of induced breeding techniques to the private sector has been critical for the more widespread 78 Little, D.C. and Edwards, I? culture of riverine carps and catfish-two classes of fish which together constitute nearly 80% of all cultured fin fish inAsia (FAO, 1995). A major comparative advantage of aquaculture to animal husbandry is the high fecundity of most cultured fish species. This both reduces the cost of production and accelerates growth in the number of farmers that can enter aquaculture. It has also allowed both rapid introduction and dissemination of new species. Movements of the major groups of carps (Chinese and Indian Major carps, west and east, respectively) have had enormous impacts. Chinese carps, particularly the phytoplankton-consuming silver carp, are now highly favoured by commercial hatcheries and constitute an important part of farmers' polycultures in India and Bangladesh. In contrast, the native carps of Bengal, rohu and mrigal, make up more than half the output of many hatcheries in North Vietnam (Little and Pham, 1996). This has happened in little more than a decade and is the net result of importing a mere few hundred small fish, as breeding animals, in each direction. An emerging contradiction is the exotic tilapias. Since their introduction to Asia as recently as the 1940s to 196Os, they are now having a major impact, despite much lower fecundity than the carps. Dubbed as the `aquatic chicken' (Maclean, 1984), comparison with the chicken is apt because of its comparable bland white flesh, low cost of production and suitability for intensification. A natural poultry-like habit of brooding their own eggs has constrained the development of methods to mass-produce seed. Whereas a skilled technician can produce millions of seed from a few dozen carps, tilapias produce relatively few eggs on each occasion they spawn due to the advanced parental care that female tilapias lavish on their eggs and young by incubating them in the mouth. These propensities together with an aseasonal and asynchronous spawning habit are serious problems for hatchery managers used to carps. However, intensified management of breeders and artificial incubation can revolutionise hatchery efficiency in a similar way to poultry (Little, 1989). Improved management of breeding fish, including selection, is constrained by the nature of aquatic culture systems, the high fecundity of most fish species and poorly developed marking systems. Inbreeding and bottlenecking can occur rapidly in isolated populations and through poor hatchery practices (Eknath and Doyle, 1985). When these problems have become acute they have been overcome by new introductions from the field although novel, practical techniques for farmers are being developed (Brzeski and Doyle, 1995). The lack of `improvement' in the past has raised expectations that selection can bring returns similar to those achieved by animal breeders. Selective breeding programs are already well developed for the common carp (e.g. Kirpichnikov et al. 1993), channel catfish (Brooks et al. 1982) and the Atlantic salmon (Gjedrem, 1983). However, impacts in Asia to date have been minimal although a major effort has begun with the Nile tilapia (Eknath et al. 1993). In general, these programs appear to have most relevance for intensive, commercial aquaculture. The complexity of designing and managing selection programs tends to focus efforts to produce fast growth in optimal and homogeneous environments: `improved' breeds are selected for performance under intensive conditions. As with monogastric livestock, the sustained performance of `improved' breeds of fish by smallscale farmers may be harder to attain, particularly without upgrading the culture system. The role of local institutions, seed trading networks and the farmers themselves must all be considered, in addition to production of improved germplasm under controlled conditions in well-funded centres. Nutrient source, form and application Extensive Systems Naturally occurring feed that supports extensive production of fish and livestock may occur within the system or be based on nutrients brought in with water flows, such as occurs in seasonal flooding. Typically the boundaries of the production unit are indistinct as there may be reliance on common property resources, whether conventional pasture or ponds, or in some form of ranching for both livestock and aquaculture. The ranching of fish in which rivers and water bodies are stocked is well-established in developed countries. It is also developing to sophisticated levels in freshwater lakes in Bangladesh around the organisation of fishermen's groups (Middendorp et al. 1996). The issue of legal ownership, easily settled with branding of `wild' and `semi-wild' stocks of livestock, has been a major constraint for fish stocks, which the use of sophisticated genetic tools now promises to overcome. Complex social issues often affect the use of communal water bodies for aquaculture, constraining any form of intensification although they may still be of major importance in terms of household nutrition (Lorenzen, in press ; Little et al. 1996a). Linkages between extensive livestock and fish culture are typically weak, through the limited amounts of manure, which are valued for use elsewhere in the farming system (Little and Edwards, 1994). However, the multipurpose nature of farm ponds means that livestock may utilise ponds for wallowing and defecation with positive effects on fish production. Semi-intensive systems Both the theory and practice of fertilisation of terrestrial and aquatic systems are at different stages of development because aquaculture has a relatively recent and weak scientific base (Edwards et al. 1988). A wide Inland fish and livestock producton in Asia 79 range of organic wastes is used in aquaculture today, ranging from the manure from feedlot livestock to human waste in the form of sewage or nightsoil and by-products of agro-industry. Fertilisation of fish ponds with organic manure, the basis of traditional Chinese integrated farming systems involving aquaculture, is still largely the result of farmer experience rather than scientific principles. It has been appreciated for a long time that the pond could not economically be only the stall, but rather the `stall and pasture' in traditional production of common carp in Europe (Schaeperclaus, 1933). The direct use of inorganic fertilisers is less widespread in aquaculture than in agriculture although fertilizer use is being promoted (Edwards et al. 1996). On resource-poor farms where livestock are typically few, the use of inorganic fertilisers to supplement onfarm wastes may be the only realistic means to produce yields that meet farming households' needs, given typical constraints of land, water and labour (Edwards, 1993; Edwards et al. 1996a,b). The more widespread and intensive use of inorganic fertilisers in aquaculture does raise issues of sustainability. Alternative sources of nutrients produced on farm such as nitrogen fixing holla-habaeba may have potential in certain contexts (Caguan, 1994) but are generally land and water intensive. Green manure in the form of terrestrial legume leaves from nitrogen-fxing perennial bushes such as Leucaena spp. and Sesbania spp. may also be used as partial inputs to semi-intensive fish culture. However, given the need to harvest and transport them, their strategic use as ruminant feeds or conventional green manure (Aye et al. 1994) probably has more potential (Little et al. 1995). A major difference between semi-intensive livestock and fish production is the possible likelihood of greater exploitation of feeding niches in aquatic systems through polyculture. Many fish species have broader feeding niches than macrophagous ruminants. This is fortunate because the food supply in a fertilised pond varies much more than that from a conventional terrestrial pasture.The microalgae that typically dominate fertilised ponds in association with zooplankton, bacteria and benthic animals are subject to periodic succession and change in an unpredictable and uncontrollable manner. Fish culturists cannot sustain continuous algal cultures in large open systems whereas practical improved pasture and range management are well established for ruminants. Some types of microalgae are known to be nutritionally superior to fish that can extract and digest them but the scientific understanding of how fish utilise natural feeds is rudimentary. The basis of the Nile tilapia's digestion of the blue-green alga Microcystis aeruginosa was described only in the 1970s (Moriarty and Moriarty, 1973). Many fish species are versatile and opportunistic feeders. For example, the silver barb (Puntius gonionotus), although known to be primarily macrophagous, is extremely insectivorous given the opportunity. This provides both a dilemma and an opportunity since the food organisms within fertilised pond are likely to be highly diverse and their availability cyclical. Large amounts of phytoplankton-derived detritus are believed to the major source of nutrition for a variety of fish species besides silver barb that would otherwise filter feed them with difficulty. The detritusbacterial aggregate has been proposed as a major under exploited niche for tirther intensifying low-cost systems that could utilise fanra-produced detritus of low value (Schroeder, 1978; Schroeder et al. 1990). Unfortunately, use of large amounts is constrained by their effect on water quality, particularly on dissolved oxygen (Colman and Edwards, 1987), and the low availability of nutrients, especially nitrogen, in such wastes that tend to be refractory. Several important aquaculture systems are largely detrital-based, however, including snakeskin gourami (Trichogaster pectoralis) in Thailand (Boonsom, 1986) and red swamp crayfish in the southern USA (Caffey et al. 1996) . Fish such as common carp and Nile tilapia stocked in rice fields generally appear to graze periphyton-detrital aggregate (Chapman, 1991). This may be amore efficient strategy than filter feeding alone, even in principally microphagous fish such as the Nile tilapia (Dempster et al. 1993). Fish also graze on a range of meiotiuna, insects and crustacea in their various life stages, in and around the sediments, in the water column (planktonic or motile) or attached to natural or artificial substrates (Shrestha and Knud Hansen, 1994). Feeds that supplement natural feeds produced in the system, whether plankton or detritus, are commonly given to raise fish yields in fertilised systems in the same way that supplements are provided for grazing ruminants and scavenging pigs and poultry. In smallscale farming systems the use of common supplementary feeds such as rice bran produced in village rice mills may be limited in both quantity and quality. Their use in fish culture may also compete with livestock (Little et al. 1996b; Little and Edwards, 1994). Improving the quality of on-farm produced feeds is possible through using mixtures of available ingredients. Upgrading locally available by-products to improve their feeding value for fish in fertilised systems is also technically feasible (New et al. 1993; Edwards et al. 1996b). The production and feeding of on-f= green fodder to fish, rather than to ruminants, appears to be limited, partly by ant&nutritional factors (Yakupitiyage, 1993). An additional major constraint is that only a single species, grass carp, feeds voraciously on a range of green fodder. In practice the land and labour required to grow, harvest and transport fodders may constrain their use (Edwards et al. 1996b). The highest quality green fodder such as water spinach (Ipomoea aquatica) also has an opportunity cost for human and livestock foods. 80 Little, D.C. and Edwards, I? Intensive systems Nutritionally balanced complete feeds for livestock and fish raised in feedlots are based largely on materials derived from agro-industry, and are dependent on fossil fuels (Preston, 1990). The development of fish and shrimp feeds, typically by agribusiness that produces livestock feeds, has proved a key factor in the intensification of aquaculture. As poultry and swine feed production pre-date fish feed manufacture, with every stage of feed development found in Asia (New and Wijkstrom, 1990), feed companies identify the latter as a key area in which to grow and diversify their business. The development of complete feeds for fish was limited until the early 1950s by a poor understanding of the nutritional requirements of the largely carnivorous, mainly salmonid, fish raised in North America (Rumsey, 1994). Once the special importance of vitamin B,, and folic acid was understood, the formulation of nutritionally complete diets became possible. Developments in production of feeds that float or sink, depending on requirements, and are water stable, have occurred over the following 40 years for a wide variety of species. The biggest single stimulus for the development of pelleted feeds in Asia was the boom in coastal rather than inland aquaculture when culture of black tiger shrimp (Penaeus monodon) began to develop rapidly in the 1980s. Hatchery development that allowed juvenile shrimp to be produced to demand spurred intensification away from a reliance on natural seed and feed. Taiwan with well-developed aquaculture and feed infrastructure set the pace, and Taiwanese companies remain active around the region. However, Thailand's fish feed business was already established to supply a large domestic catfish (Claris spp.) industry before shrimp farmers became the main source of demand and has since developed a large range of feeds. The latest trend in the rapid development of the shrimp culture business is a move inland to raise this species in new unpolluted sites. This practice is expected to lead to new conflicts, particularly regarding resource use and potential adverse environmental impacts. The feed business has allowed intensive aquaculture to become a year-round operation and to expand to regions without suitable feeds. Intensive aquaculture no longer need rely on seasonal fluctuations in the availability of small wild fish for feed. Formerly, intensive farms raising trout far from the sea used fresh meat (Schaeperclaus, 1933) or maggots raised on slaughterhouse waste (Rumsey, 1994). Old horses, the pre-eminent form of draught power, were probably the single major source of fish feed. Traditional trash fish-based systems described above have increasingly been replaced with dry feed formulations based on marine fish meal, except in certain exceptions in which some fish species feed only on moist feed formulations containing tiesh fish (Czavas, 1989). The continuing dependence on fishmeal, especially for the high valued marine shrimp and fin fish, has changed overall demand for fishmeal with consequences for livestock production and fish consumers alike (New, 199 1). Increases in demand for fishmeal in shrimp caused knock-on effects in Thailand where higher feed costs led to increased consumer prices and a slump in chicken exports (New and Wijkstrom, 1990). In general the livestock sector has responded to increased fishmeal scarcity as there is a major difference in the proportion of fishmeal used in livestock and fish feeds. The level of fishmeal in poultry rations has been reduced by more than 80% in the US over the last two decades by substitution with alternatives (Rumsey, 1993). Aquaculture is already estimated to absorb in excess of 12% of the world supply of fishmeal (Pike, 1990) and this is expected to increase further. Attempts to reduce levels of fishmeal inclusion in feed for carnivorous fish from the levels of 30-70% typical of salmonids have been less successful. Fish acceptance of such feed declines although many species of carnivorous fish have been shown to tolerate high dietary levels of soybean meal experimentally (New and Wijkstrom, 1990). It is also likely that increasingly the small, marine pelagics used for fishmeal will be used for direct human consumption (Tacon, 1996). Processing to surimi and use of fishmeal for speciality and valueadded feed products such as pet foods and rumen bypass diets is likely to increase (Rumsey, 1993). The experience of the livestock feed industry could indicate likely developments in aquaculture, and thereby avoid the so-called `fishmeal' trap (New and Wijkstrom, 1990), i.e. dependence on a finite and declining resource by an expanding market. Substitutes for fish diets will follow as the price of fishmeal continues to rise in real terms and processing techniques to improve the value of plant-based protein sources are further refined. Furthermore, cultured fish species that are omnivorous or herbivorous and can tolerate low little, or no fishmeal in complete diets, such as channel catfish (Ictalurus punctatus) and Nile tilapia, will become more competitive. Currently herbivorous and omnivorous fish, although comprising nearly 90% of farmed fish globally, consume less than 10% of the fishmeal used in fish feeds (Tacon, 1996). Intensive food production, irrespective of . dependence on fishmeal or soybean has high social and environmental costs. Large amounts of nutrients and fossil fuels are required to harvest ingredients and/ or to produce or transport them. Moreover, the tendency for high-density production to pollute the environment remains a major unresolved issue. /n/and fish and livestockproducton in Asia 81 Pest and hygiene management Livestock and fish health Pests and diseases can undermine the