Aquaculture And Integrated Farming System

Fisheries are destined to play an important role in human nutrition but it is becoming a luxury food in some of the countries. Utilization of grain and animal protein as feed for aquaculture may not be economical as it might reduce the food availability for human consumption. The world’s energy and food crises are redirecting the attention to an intelligent and wiser use of all resources and integrated fish farming offers a solution to the problem.

Integrated Fish Farming may be defined as the association of two or more normally separate farming systems which become part of the whole farming system. The major features of this system include recycling of waste or by-product in which the waste of one system becomes the input of other system, and efficient utilization of farm space for multiple production.

Integrated livestock-fish, poultry-fish, and rice-fish farming and crop rotation in fish ponds have been well developed and practiced in countries like China, Hungary, Germany and Malaysia. The freshwater aquaculture in Pakistan and more so in Sindh, has been largely organic-based. The inputs for it derived are from activities of agriculture and animal husbandry with plants and animal residues forming the major component of feeds and fertilizers in crop polyculture. Small - scale farmers in this part of the world, have sustained themselves by practicing different kinds of crop diversification for centuries. About 70% of Pakistan’s population live in rural areas at subsistence or near subsistence level. The rural folk in the region are greatly under-nourished and need not only a large supplement of animal protein in their diet but also new sources of gainful employment. Pakistan being an agrarian economy, produces large quantities of plant and animal residues. It is known that the country supports the large bovine population of over 59.3 million cattle heads along with 79.4 million sheep and goats 357.8 million poultry and other livestock. Activities like goat production and rabbitry, poultry, etc. apart from providing for diversification of farming systems, also provide huge quantities of organic material, that may become resources in the aquaculture system. The agro-based industries like distilleries and food processing plants also produce the different kind of waste that could be recycled to aquaculture apart from the well known resource-the domestic sewage.

Ecosystem of Integrated Fish Farming is characterized by Trapping of solar energy and production of organic matter by primary producers, Utilization of primary producers by phagotrophs or tertiary consumers, Decomposition of primary producers and phagotrophs by saprotrophs or osmotrophs, Release of nutrients for producers. Apart from above, the food chain within the ecosystem also thrives and subsists on animal waste which gets access through feed, autotrophic production and heterotrophic production i.e. certain bottom feeders like Cyprinus carpio and Cirrhinus mrigala directly utilize the organic particles from feed which are generally coated with bacteria along with other material, where as some of the decomposed protein of waste products provides nutrients for the micro-flora (autotrophs), while non-mineralised protein provides food base for bacteria and protozoa (heterotrophs). Temperature, light, micro and macroflora, inorganic nutrients, carbon, phosphorous and nitrogen are the basic inputs required for photosynthesis process. However, the micro fauna (zooplankton) feed on small manure particles coated with bacteria. In the process, bacteria are digested while rest is excreted. In this heterotrophic production system micro fauna (protozoans and zooplanktons) are produced finally shortening food chain. This system of production is not linked with the process of photosynthesis.

Integrated fish farming system utilize the waste of live stock, poultry and agriculture by-products for fish production. About 40-50 kg of organic manure can produce 1 kg of fish. Fish farms having an integration with mulberry cultivation, sericulture and silk extraction from cocoons allow the pupae to be utilized as fish feed and the worm faeces and wastewater from the processing factory to be used as pond fertilizers. Pond silt can be used as fertilizer for fodder crops which in turn can be used to raise live-stock and poultry or as fish feed. Thus a recycling of waste is done in integrated fish farming system.

The scope of integration in a fish farm in considerably wide. Ducks and geese may be raised on the pond. The pond dykes may be used for fruit plants and mulberry cultivation or for raising goats, cattle, and dyke slopes for fodder production. From integrated fish farming systems not only fish but meat, milk eggs, fruits, vegetables, mushrooms etc. can be obtained. This system fully utilizes the water body, the water surface, the land, and the pond silt to increase food production for human consumption. The integrated fish farming system holds great promise and potential for augmenting production, improvement in rural economy, generation of employment leading to poverty alleviation.

Integrated Aquaculture System is not merely a fish culture but it is essentially a blend of variety of fishes with crops, horticulture, livestock, poultry, birds etc. The system may have an integration such as rice and fish, fish and prawn, horticulture and fish, duck and fish, fish and livestock, rabbit and fish, goat and fish, poultry and fish and so on so forth. The features of such integration may however vary and the output is always associated its management and utilization of inputs and resources.

Rice-Fish System

Rice is the dominant cereal crop in Asia. It is the staple food of over 1.6 billion people in the world, mostly in Asia where 90% of all rice is grown and eaten. For most rural farmers, this single crop is virtually their sole livelihood. The practice of collecting wild, naturally occurring fish for food rice field is probably as old as rice cultivation itself.

The reason for decline in rice-fish culture has been the introduction of various insecticides, which are harmful to fish. Rice-fish culture plays an important role in rural economy of Asian countries. This is because fish culture lends itself well to small labour intensive farming operations. It can be used in conjunction with rice cultivation to increase productivity. Rice fields from the natural habitat for a larger variety of indigenous species of fish which gain entry only from the nearby perennial water bodies. The fishes feed and grow on natural food available and the farmers usually collect the fish during rice growing season and / or when the water level subsides.

Scientific rice-fish systems can ensure higher productivity, farm income and employment in these areas.

Fish and Prawn

Catla, rohu, mrigal and common carp in combination with freshwater giant prawn are stocked in equal proportions @ 10,000 individual / ha. These are fed with rice bran and mustard groundnut oil cake @ 2-3% of the total body weight. Manuring schedule includes application of cow manure at 10 t/ha/yr, while liming is done @ 200 to 500 kg/ha. These are harvested periodically along with receding water levels.

Horticulture on the Dykes

After the harvest of rice certain crops which require lesser amount of water like water melon, groundnut, vegetables, cow pea, etc. can be grown. Top of the bund which is 10% of the pond area is utilized for growing vegetables and fruit bearing plants.

Rice-fish system results in 168% intensity of cropping in field and 400% on bunds as compared to 52% in the case of traditional monocropping of rice. Rice-fish system provides a net annual income of around Rs. 30,000/ha in the first year which accounts for about twelve folds income over farmer’s traditional practices and three folds over the improved monocropped rice.

This system encourages synergism between rice and fish leading to increase in grain yield by 5-15% and straw yield by 5-9%. It facilities crop diversification, there by reducing investment risk. It promotes gainful linkage between rice, fish, prawn, vegetables, fruit crops and other resulting in better resource utilization as well as conservation of the ecosystem. It generates year-round employment in the farm.

Horticulture-fish system

Ponds are well situated for growing horticultural plants. The top, inner and outer dykes of ponds as well as adjoining areas can be best utilized for horticulture crops. These crops are fertilized by the pond silt and fertile pond water is used for watering. The success of the system depends on the selection of plants, which should be Dwarf variety, Less shady, Evergreen, Seasonal, and Highly remunerative.

Dwarf variety of fruit bearing plants like mango, banana, papaya, lime can be grown around the pond. This will not obstruct the sunlight to the water bodies and also the pond will be free of dry leaves. Ginger, turmeric, chilly can be grown as intercrops. Ponds dykes are used for growing vegetables solo as well as intercrops. During summer season, brinjal, tomato, chilli, gourds, cucumber, melons, ladies finger is cultivated while during winter peas, beans, cabbage, cauliflower, carrot, beet, radish, turnip, spinach, etc, is raised. Pond slit and pond water is used for providing nutrient for these crops.

Flower bearing plants like tuberose, rose, jasmine, gladiolus, marigold, cassandea, chrysanthemum are grown on the pond dykes. These flowers have tremendous market potential in the cities which provides additional employment to the farmers.

Farming Practices

Farming practices are carried out on broad dykes which can stand ploughing and irrigation. Ideal management involves utilization of the middle portion of the dyke covering about 2/3 of the total area for intensive vegetable cultivation and the rest on the area along the length of the periphery through papaya cultivation keeping sufficient space on either side or netting operation. Semi intensive farming is done where the dykes are not good. Crops of longer duration like beans, ridgegourd okra, papaya, tomato, brinjal, mustard and chilli are suitable for such dykes. Narrow dykes are suitable for cultivating sponage gourd, bottle gourd citrus and papaya. Where the dykes are shaded ginger ad turmeric can be cultivated.

Fish Culture Practices

Large quantities of leaves of cauliflower, cabbage, turnip and radish are available at the farm site. These are fed to the fishes as feed. Grass carp is one of the ideal fish for this purpose. A monoculture of grass carp with a stocking density of 1000/ha will give a production to the tune of 2000 kg/ha/yr. During  summer, amaranth and waterbind weeds through cutting are fed to the grass carp. If possible, common carp can also be added Grass carp is a voracious feeder. Only part of the intake food is digested, while the rest released as faecal matter which serves as a good feed for the common carp. This results in additional production without involving any cost towards carp feed. In mixed culture of grass carp along with rohu, catla, mrigal in the ratio of 50:15:20:15 at a density of 5000 fish per hectare results in yield of 3000 kg/ha/yr.

Duck-Fish Integration

Duck-fish integration is the most common integration, mainly practised in China, Hungary, East Germany, Poland, Russia and upto some extent in India. It utilizes the mutually beneficial biological relationship between fish and duck. Asia is considered to the holy land of the domesticated ducks, but the best breeds and strains currently available have been developed for their excellent egg / meat production in Europe and America through systematic breeding, feeding, management and disease control.

In the West and other affluent countries, duck meat is a delicacy, and ducks are mainly reared for table purposes. In some countries, duck eggs are not popular because of the fear of possible Salmonella infection. Duck eggs are an important source of food. These are very cheap to produce and can play an important role in balancing the diet of the people.

Fish-Livestock System

Fish farming using manure has long been practiced all over the world. Integrating fish and livestock farming reduces the necessity to purchase fertilizers and fish feed, and increases the income generated by the fish farm.

Animal sheds can be built close to the fish ponds to simplify the handling of the manure. The faeces and urine may be collected separately. If the floor is higher than the pond dyke, a manuring ditch can be dug to collect the faeces and urine together and the mixture can be flushed directly into the fish ponds. This method saves time and labour. The area of the fish pond to be matched with the number of livestock and waste food; the species ratio and target output of fish etc. The frequency of manuring depends on the conversion of the manure, which changes seasonally, and the fluctuation of food organisms in the fish ponds. Cow faeces and urine are beneficial to filtering and omnivorous fishes. Therefore, silver carp and catla are usually the major species with assorted omnivorous fish (common carp) and herbivorous fish (15-20 percent). The optimal output of herbivorous in fish-cow integration should be around 12 percent of the total output of the pond. With more herbivores, supplement feeds must be applied.

Rabbit-Fish Integration

Rabbit can play an important role as a non-conventional meat animal for hilly, tropical rain forests, roughage, legumes and horticulturally rich areas. Until recently, rabbit was considered, as a pet animal by the common citizens. For the professionals, it was an experimental animal. But currently rabbit has emerged as an alternate meat source for the future. Rabbit meat has been regarded as a dieticians choice for the health-conscious meat consumers. Rabbit meat is low in fat content in comparison to chicken, mutton and beef. Among the food animals, rabbits has the highest reproduction rate and can attain the growth rate comparable to modern broiler chicken. Rabbit fur skin which is an important bi-product supplements the farmers’ income.

Integration with Goats

Goat farming is an age-old practice but its integration with fish culture has not been explored. Goats not only provide meat and milk but also a good amount of manure. Annual production of manure from a goat is around 1.5-2 tonnes per year. If animal manure is not properly used, it causes pollution of water and environment. It has been observed that 40-50 kg of animal manure produce 1 kg of fish. Animal manure and green fodder can totally replace the commercial feed for fish farming achieving a similar fish production. The goat is a versatile animal. It is known as the poor man’s cow. Goats can be kept with little expense on undulating lands with an inexpensive shelter.

Poultry-Fish System

A simple and economically viable system of fish-cum-poultry farming has been developed. Under the system, the poultry droppings of fully built up poultry litter is recycled in the polyculture  fish ponds which results in production of 4,500-5000 kg fish. Broiler production give good and immediate returns to the farmers.

The most important factor a farmer should consider before taking up broiler production is to investigate the market conditions, where the product will be sold. There should be steady demand for his chickens, so that all the stock could be disposed of immediately when they are ready for market. Success in broiler production depends mainly on the efficiency of the farmer, his experience, aptitude and ability in the management of the flock.

The waste animals feeds and animal excreta is utilized to increase the biological productivity of water. Probably supplemental feed and fertilizers may not be needed in such a system and the cost on inputs, therefore, may be reduced.

The ponds are prepared and stocked in the same way as in duck-fish farming. The built up poultry litter removed from the poultry sheds is suitable place and is applied to the pond in daily doses @ 40 - 50 kg per hectare per day every morning after sunrise. The application of litter is deferred on the days when algal bloom appears in the pond.

It has been estimated that one tonne of deep litter fertilizer is produced by 25-30 birds in a years time. As such 500-600 birds are adequate to produce manuring for a hectare of water area under polyfish culture.

Utilization of Domestic Sewage for Aquaculture

Development and pollution are two interrelated processes that have been causing great concern to the planners. With increasing population in the country, the quantities of wastewaters generated have been increasing beyond treatment capacities, apart from a host of industrial effluents in the recent years and solid wastes. Several processes of treatment include the conventional activated sludge and trickling filter methods, oxidation/waste stabilization ponds, aerated lagoons and variations of anaerobic treatment systems, the latest one being the Up flow Anaerobic Sludge Blanket (UASB) process.

It is increasingly being recognized that sewage is just not a pollutant but also a nutrient resource, as evidenced by about 90 t of nitrogen, 32 t of phosphorous and 55 t of potassium valued at Rs 61 million that could be recovered from the country’s domestic sewage daily. Traditional practices of recycling sewage through agriculture, horticulture and aquaculture, they being basically biological processes, have been in vogue in several countries. The sewage-fed fish culture of Munich in Germany and Bheries in Calcutta are world-famous. Emphasis on these practices has been on the recovery of nutrients from the wastewaters. Taking culture from these practices and deriving from the new databases in different disciplines of wastewater management, aquaculture is being proposed and standardized as a tool for treatment of domestic sewage.

Aquaculture for Wastewater Treatment

Several variations of models of aquaculture for treatment of domestic sewage have been proposed. Employment the biotic components in an aquatic ecosystem that include bacteria, algae, duckweeds, macrophytes and fish/shellfish, the principles of all the models has primarily been dilution, oxidation, reduction of BOD, COD and the suspended solids along with nutrient recovery in terms of biomass. Several food chains operate in these systems, rendering the influent, nutrient-deficient and less harmful to the environments to which they are discharged.

Fish ponds serve as facultative ponds for sewage treatment, also providing oxygen output

form to photosynthesising algae and macrophytes. The macrophytes also serve as nutrient

pumps, reducing the eutrophication effects that the sewage is likely to cause in the natural

waters. It has been demonstrated that the ponding reduces the bacterial loads by 2-3 long

units and bacteiophage loads by 3-4 long unit seen at sewage loading of 100 kg COD/ha/day. With no evidence of build-up on the concentration of excreted micro-organisms in pond water with either an increase in organic loading or time, it has been shown that the faecal coliform concentrations reduced by 4 log units within 24 hours of retention in the ponds.

Studies have also shown that about 1 MLD of domestic sewage could be treated over an area of one hectare through water hyacinth reducing the BOD and COD by 89 and 71% respectively, along with removal of nitrogen and phosphorous to extents of 89 and 50%. Aquaculture being a product-oriented practice, public health concerns are being raised with regard to sustainability of consumption of fish/shellfish from such systems. These pertain to the microbial load of the produce, possibilities of harbouring human pathogens, accumulation of pesticides residues, heavy metals etc. Accordingly, the sewage-fed aquaculture models are being modified with incorporation of plant cultivation prior to application of wastewaters in his fish pond, also followed by necessary deprivation measures.

A New Model

The new aquaculture model for treatment of domestic sewage integrates the culture of algae, duckweeds and fish/shellfish. The aquaculture system network comprises 18 duckweed ponds (25 m x 8 m x 0.5 m) and two fish culture ponds (50 m x 20 m x 2 m). In addition, two marketing reservoirs (40 m x 20 m x 2 m) are also provided for the depuration and marketing of fish/shellfish produce. The treatment strategy consists of allowing a retention time of two days in duckweed ponds and a further retention time of three days in fish ponds at the second stage of treatment. With a total retention time of 5 days n the integrated culture system, a reduction in BOD levels of the influent to the extent of 60-80% has been observed during different methods.

The system employs the aquaculture components of the highly-priced, proteinaceous blue-green alga, Spirulina Sp; duckweed, viz, Lemna, Wolffia, Sprirodela and Azolla; carp species of catla (Catlacatla), rohu (Labeo rohita), Mrigal (Cirrhinus mrigala), silver carp (Hypophathalmichthys molotrix) and grass carp (Ctenopharyngodon idella) and freshwater prawns (Macrobrachium rosenbergii) and (M. malcolmsonii). The yield rates of different components are 2-3 g/m2/day for Spirulina sp., 75-100 g/m2/day in case of duckweed and 3-4 t of fish/ha/yr.

It is noteworthy that this model of treatment of domestic sewage serves the dual purpose of sewage treatment rendering the effluent fit for disposal into river systems as per the prescribed standards and recovery of nutrients into the protein-rich fish flesh. Requiring about one hectare land area for the network of duckweed ponds, fish ponds and marketing reservoir along with the bunds and road for treating 1 MLD of sewage, the process does not have power requirements as in cases of other treatment methods. While the alga, Spirulina, and fish/shellfish have ready market for human consumption, the duckweeds produced could be processed as cattle/fish feed as also biofertilisers in agriculture and aquaculture. The model thus envisages a wholesome, integrated, eco-friendly practice for treatment of wastewaters that could be adopted elsewhere in the country, ideally suited for towns with about a hundred thousands human population.

Problems in Integrated System

Most of the current integrated farms in south east Asia are operated in the traditional way without proper planning, modern technology or modern farm management techniques and rely on personal experience. Marketing is therefore a recurrent problem except in years where demand is sufficient. Fish disease constitute a further major problem with the farmers cannot solve by themselves since they have inadequate experience and knowledge, and such knowledge is not as readily accessible as with other farm animals where feed manufacturers or veterinary supply companies offer services to assist farmers in many cases. A further problem for farmers is the shortage of credit and working capital, which forces them to contact their produce sales to middlemen, usually at unfavorable prices.

Future Trends

Fish is relatively cheap and higher in protein content than other animal protein sources. Increase of food supply to cope with the high rate of population increase requires much more than an increase in agricultural land. Land is a limited resource and if more land is used in agriculture, the forestry will soon be reduced to a degree which will be harmful to the environment. Also, the cost of production could rise. Therefore, a method is needed to produce more food from existing agricultural land, and integrated farming offers a possible solution. Integrated farming will probably play a very important role in natural development, as well as in the national economy.

Research Needs

Although integrated farming has now been proved to be highly profitable, its practice remains very limited in scale. This is because the relevant scientific and technological information on diversification of methods is unavailable to farmers. To remedy this, there

must be a bridge between the information sources and the farmers, perhaps through extension services. A multidisciplinary approach is needed, including technological, economic, social and political aspects which are interrelated. Any approach must, however, be relevant to national economics, social and environmental conditions and to the farmers need.

References

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