In China, there is a great variety of integrated fish farms involved in lake, reservoir, and pond fish culture. This chapter deals with the design and construction of an integrated fish farm that combines pond fish culture with crop, livestock, and poultry farming as well as sideline occupations.
An integrated fish farm is a production base. The design and quality of construction directly affects the investment and the deployment of labour in construction and, more importantly in fish, livestock, and poultry production. The following requirements should be emphasized in calculation and design. All information should be gathered for detailed analysis and comparison, providing a reliable scientific basis for site selection.
The most important requirement in constructing an integrated fish farm is the water supply. Irrespective of its origin, water can be used provided it is of desirable quality. However, if the water source is near a factory or mine sewage, the water quality must be examined for possible toxicity to fish. For example, the effluent from metallurgical factories contains lead; instrument plants or table salt electrolyzing plants produce mercury; the effluent from coking plants or petroleum and gas industries contains phenols. All of these materials either kill a fish directly or accumulate within the body and harm the consumer. Such water sources should be avoided.
The waste water from food-processing mills such as slaughterhouses, breweries, and beancurd works is rich in organic materials. This water can be beneficial to fish farming by way of fermentation, sedimentation, or controlled introduction.
Underground water often contains an excess of carbon dioxide and lacks oxygen. Also, its temperature is too low for warm-water fish. Underground water should be completely exposed to the air before it is used. The underground water flowing out of coal or sulphur mines is too acidic for fish culture.
The acidity or alkalinity of water represents its hydrochemical quality. In general, the optimum pH for pond fish culture is between 6.5 and 8.5. Beyond this range, fish yield is affected and high mortality could occur.
Many cultured fish species, such as tilapia, mullet, red-eye mullet, milkfish, and common carp, have a strong salinity tolerance. A salinity of 5‰ will not harm common carp; however, at 11.5‰ the fish will die (Soller et al. 1965). To determine whether the water source is fit for fish farming, the growth of the fish native to the water should be examined. A more reliable method, however, is to rear fish in that kind of water in a small container for a period of time as well as to physiochemically analyze the water.
When investigating water quality, it must be remembered that in the flood season the water may be less toxic than in the dry season, when, because of evaporation, the concentration of toxic elements will increase. If such a water source is used, the reserve water supply should be used in the dry season. Only when the water to be used has been established as non-toxic and suitable for fish farming, can any other problems be considered.
The water supply should be abundant and relatively stable, able to meet the needs of the fish ponds at any time. Therefore, it is important to gather first-hand information on the seasonal fluctuation of the water level, the agricultural irrigation requirements for crop farming, and the water requirements of the fish ponds. These are the primary factors in designing the fish pond area because a deficiency of water will prevent production potentials from being achieved. Therefore, the relevant information on hydrology, meteorology, topographical features, and edaphic condition should be collected in detail and this data, in conjunction with the water depth needed per unit area of fish pond (based on the volume of flow in different seasons) can be used to determine the adequacy of water supply both for fish ponds and fields. If a farm is constructed along a lake, river, or reservoir, information on the highest and lowest water levels in the past must be obtained and the areas with the most stable water levels should be selected. Thus, draught through leakage in the dry season and overflow in flood seasons can be avoided. Flood-prevention measures should be taken as in small-scale irrigation works: it will not be offended by flood within 25 years. The farm should be kept above the safety line. Water-logged areas and depressions with too much rainfall should not be selected for a fish farm.
Soil characteristics greatly affect the quality of pond construction and influence fish and crop yields. Therefore, soil quality should be carefully determined. In determining soil quality, it is insufficient to just examine the topsoil. Enough samples must be taken from various representative spots. The sampling depth should exceed the depth of the pond by 1 m. The soil should ensure that pond dikes will not leak or collapse. This is especially important for manured ponds.
Loam conserves water and fertilizer and is well-aerated. Therefore, it is the best soil for dike construction. Sandy loam also conserves water; however, it has a weak coagulation and, therefore, is unsuitable for dike construction. Clay conserves water well. It can be used on the pond bottom; however, because it cracks when dry, it is unsuitable for dike construction. If sandy loam or clay are used for dikes, the crown should be widened and the gradient of the slope decreased. Gritty soil, sandy soil, and silty soil are very porous and poor in the retention of water and fertilizer. They are poor materials for dike construction; however, if needed, sand could be used with clay.
Attention should also be given to the contents of the soil that influence fish growth. If the iron content is too high, colloidal ferric hydroxide will form in the water and settle on the pond bottom. This rusty sediment often adheres to fish gills and hinders respiration, especially during egg hatching and fry rearing. An iron-rich soil is russet brown or green and is relatively easy to identify.
Soils with an excess of decaying matter have lower water and fertilizer-retention power. This material collapses easily if used in the pond dike. In tidal areas and swamps, pond construction is more difficult because the ground water level is high. The operating cost may be much higher. These areas are too low to allow complete drainage and water temperature raising as required for proper management.
Because of the variety of integration on an integrated fish farm, the productivity of the land can always be fully utilized. Nevertheless, it is desirable to construct a fish farm on flat land. Generally, there is no problem in setting up a farm in a hilly district because the slopes are appropriate for afforestation, fodder cultivation, and livestock production. In designing fish ponds, gravitational flow can be exploited to reduce soil excavation and energy consumption.
Infertile land, hilly districts, valleys, or lake bay areas are preferable for pond construction; however, these topographies require greater investments and farm construction is more time-consuming. Nevertheless, the fish pond would not occupy fertile cropland; the development and utilization of wasteland is of great significance to any developing country.
Transportation and Energy
A large amount of fresh produce and processed food will be sent to the market and fishery, animal husbandry, and agricultural necessities will be purchased from the market. Therefore, the farm should be easily accessible. For example, Helei Fish Farm is located in the suburbs of Wuxi. Water or land transportation facilitates the development of the farm.
If possible, the farm site should have access to an areas rich in natural food (e.g., snails, Corbicula spp., and aquatic grasses) so that, besides the self-supplied feeds and fertilizers, there is a sufficient supply of food for the fish year-round. Electricity is the primary energy source on a fish farm so that the farm site should have easy access to a power plant. Water, road, and electricity must be within reach before beginning construction.
To develop an overall design for a farm, land area and elevation measurements are necessary. Draw up a ground plan (ichnography) with a scale of 1:500 to 1:1000 before starting any earthwork calculation or pond construction. The management items and their scale of diversification are determined by the natural conditions of the site, investment, and consumer preference. In the overall farm layout, the various departments and their facilities should be rationally arranged (Fig. 10.1). This not only involves construction and investment but also affects future operations. The farm layout must fulfill the following criteria:
Facilitate management and increase production and economic returns;
Minimize labour intensity, heighten efficiency, and protect the workers' health; and
Economize on capital construction investment and reduce material consumption.
The layout of an integrated fish farm should not only be geared to the present but also to the future. There should be room enough to implement a practical long-range program in stages according to the funds and labour force available.
The other occupations on an integrated fish farm serve fish production. The scale of crop and animal production depends upon the needs of aquaculture. Therefore, the locations and areas of the fish ponds should take priority; this is followed by the location and areas of livestock pens, crop fields, processing plants and other structures.
Aquaculture Facility Arrangements
Fish ponds are the main structures on a fish farm. They are generally outdoor earthen ponds. Fish seeds, if possible, should be produced on the farm to reduce operating costs and ensure a supply of properly sized fingerlings. This will bring out the full potential of the fish ponds and avoid the invasion of infectious fish diseases from outside.
Farms with herbivorous and grain-feeding fish as the major cultivated species need large fingerlings. The nursery ponds generally account for 25–30 per cent; grow-out ponds, 70–75 per cent. If plankton-feeding fish are the major species, the nursery ponds should account for 15 per cent and the grow-out ponds, 85 per cent. If the production scale is large and the farm intends to breed its own fry and fingerlings, spawning ponds and hatcheries must be built. The ratio of the areas of brooder ponds to fry ponds to fingerling ponds depends on the quantity of fry and fingerlings needed for farm use and sale. In general, the ratio is about 5:10:85. The ratio of the water surface to the total farm area depends on soil quality and integrated management requirements. Generally speaking, the water area occupies about 60–70 per cent. In the Wuxi area, water area accounts for 68 per cent; pond dikes, 21 per cent; inlet and outlet channels, 11 per cent. Various fish ponds are arranged on the basis of water demands and operational convenience for the purpose of increasing the survival rate of fish. The brooder ponds, spawning ponds, and hatcheries should be close to the hatching facilities. Spawning ponds and hatcheries should be built in the vicinity of the brooder ponds to facilitate brooder transportation. Fingerling-rearing ponds should be next to the fry-nurturing ponds and the food fish ponds. In other words, the fish ponds should be arranged in such a way that the various operations of aquaculture, such as fry stocking and fingerling transfer, can be carried out in the shortest possible time with the minimum amount of labour.
|Fig. 10.1. Schematic Diagram of Xi Nan Fish Farm|
Arrangements for Other Occupations
To lead the pig excreta into the fish ponds, the pigsties are generally built on pond dikes or on highlands close to the fish pond. A small farm may centralize the pigsties; a big farm should disperse the pigsties. Pigsties built on pond dikes can be easily reached by canal or road. The pig excreta is channeled into septic tanks for fermentation before it is used. This shortens the distance of transportation.
Cow shed location
Cows need both a shed and a playground. These will occupy more area than pigsties on pond dikes. Generally, intensive cow farming is practiced. The cow shed should be built near the fish pond for the easy transportation of the wastes, feeds, and milk.
Location of duck and goose pens
Duck and goose pens are built separately along the pond dikes.
Chicken house location
Chicken houses are open with good ventilation. They are almost always built on dry ground on the highlands. To prevent the outbreak of chicken diseases, the chicken house should be located away from other domestic animal houses. For the sake of transportation, however, they should be near the roads.
Fodder crop fields
Aside from the dike and slope for crop cultivation, an integrated fish farm should have special plots for fodder crop. The area of the plots depends on the fodder requirement and the land available. If the fine feeds are provided mainly by the market, less land for fodder crops is required. Wasted plots, hilly areas, and the water surface should be put into full use. Some farms even grow crop in the fingerling-rearing ponds in the off season or in lake bays and river bends.
Farm Administration Building
The farm administration building is the headquarters of those responsible for the organization and leadership of the farm. The headquarters should be located centrally in the farm for easy access.
Industry and Sideline Occupations
For the sake of marketing, convenience of transportation, comprehensive utilization of farm produce, and enhancement of employment, a big farm should establish a slaughterhouse, brewery, fish gear repair shop, and simple processing workshops for fish, duck eggs, milk, and beans. These workshops should be arranged near the source of the produce. (See Fig. 10.1).
After determining the location and area of fish ponds, the position of ponds and pond dikes and the direction, shape and size of inflow and outflow channels must be established.
Fish Pond Size
The size of a fish pond depends on the environmental requirements of fish in different stages of growth and the requirements of operational management. In general, grow-out ponds range from 5 to 10 mu with a depth of 3–3.5 m (water depth, 2.5–3); fingerling ponds, 2–5 mu with a depth of 2–2.5 m (water depth, 1.5– 2 m); nursery ponds 1–2 mu with a depth of 1.5–2 m (water depth, 1–1.5 m). The brooder ponds have the same size as the grow-out pond.
It may be necessary to construct ponds for water storage, settlement, filtering, or sun exposure. A fish pond is often rectangular, being broadest from east to west. This kind of fish pond gets more solar radiation which benefits the photosynthesis of aquatic plants, enabling them to produce more oxygen. This in turn, promotes the growth of fish and natural food organisms. The ratio of pond length to width should be 2:1 or 3:2. The length of a large pond should be increased. The width of the same types of ponds should be uniform; this requires less fishing gear and saves labour time.
All the fish ponds have the same structure with little differences in size and depth.
The embankment includes the pond dike, the partitional dike, the marginal dike, the transportation dike, and the cofferdam. The soil quality and the various uses of the dike are the main factors in deciding the width of the crown and the gradient of the slope. The dike can be narrower if the soil quality is better, the food supply is sufficient, or the land area is inadequate. Pond banks range in width from 2 to 5 m. A large pond needs a wider crown than a small pond. The width of the dikes between fish ponds and inflow and outflow canals should be kept within 5 m; the width of the dikes for pigsties, cow sheds piping, or traffic should range from 5 to 10 m. If the outflow canal is too narrow for boat traffic, the dike should be wide enough for land traffic, at least on one side of the pond.
With loamy soil, the dike slope gradient should be 1:1 to 1:1.5. With poor soil or on a grow-out pond dike, the slope gradient should be 1:2.5 to 1:3 under the water surface and 1:1 to 1:1.5 above the water surface. In a grow-out pond, a path about 0.5–1 m wide along the inner slopes should be provided for the sake of pulling nets and avoiding erosion by waves (Fig. 10.2).
A cofferdam is a structure that prevents a fish farm from flooding. It must be built 0.5 m higher than the historical peak water level. The crown width of a cofferdam is 4–6 m or even 10 m as required for the stretch against the wind and waves and the slope gradient should be large. The leeward slope should be 1:1.5 to 1:2.5; the windward slope, 1:2.5 to 1:3.5. If the slopes are well protected with grass and stone, the gradients may be reduced to 1:2. A slope several metres wide out of the dike foot should be left as a buffer zone where the aquatic plants can be planted, lessening wave attacks. If the soil is poor, an edaphic core made of soil with good coagulation should be built (Fig. 10.3).
The pond bottom is flat and it should slope from the inlet toward the outlet with a gradient of about 3‰ for a large pond and about 5‰ for a small one. A slight slope from the dyke foot to the central area of the pond aids drainage and harvest (Fig. 10.2).
Water Intake and Drainage Systems
Water intake and drainage systems maintain the water level and adjust the water quality, preventing draught and flood and the spread of fish diseases. These systems are very important and every effort must be made to ensure proper design and construction, otherwise, future operations may be endangered. An independent water intake and drainage system is required for each pond. The system includes inlet and outlet canals and other bypass channels such as aqueducts, culverts, drop basins, sluice gates, etc.
Fig. 10.2. Sketch of pond structure
Source: Chinese freshwater fish culture editorial board, 1982.
Fig. 10.3. Sectional view of flood control dikes.
Source: Chinese freshwater fish culture editorial board, 1982.
There are three types of inlet canals: general canal, branch canal, and bypass channel. The flow of water should satisfy the demand for water supply at any given time. The bottom of the inflow canal should be higher than the peak water level of the fish ponds. It should be kept dry when there is no irrigation. The sectional size of a canal is dependent upon the flowing amount of water. In cross-section, the earth dyke is trapezium-shaped with slope gradients of 1:1 to 1:1.5 on both sides. If protected with bricks and stones, it often appears to be rectangular. The slanting ratio of a canal will influence the flow speed of the water. In a field construction, the slant should be based on the slope of the land. If the slope of the land is too steep, several drop basins can be built. In constructing the canals, the following slanting ratio should be adopted: bypass channel, 1:300 to 1:750; branch canal, 1:750 to 1:1500; general canal, 1:1500 to 1:3000.
The distance of water conveyance should not be too great; otherwise, land is wasted and there are bad effects on the water supply. A general canal should supply water for 150–200 mu of fish ponds.
The inlet water locks are generally the culvert type, using underground pipes made of bricks, stones, and cement. The size of the head gate depends on the pond size, ensuring the ponds will have sufficient water at any given time. The area between the gate and the pond bottom must be cemented with stones to prevent bank erosion (Fig. 10.4).
The design of the outflow canal is almost similar to that of the inflow canals, except that the bottom of the outflow canal should be 0.3 m lower than the pond bottom. If the canal is used for drainage in the flood season, it should be large enough to drain the water in a limited time. Outlet water locks are often the trough type; however, it is difficult to close the gate tightly because of the strong water pressure. It is also inconvenient to lift it up; hence because of its easier operation, the terraced type of outflow sluice is used. The sluice gate should be big enough to drain all the water in a limited time (Fig. 10.5).
The inflow and outflow canals should be arranged alternately: one side for irrigation and the other for drainage. This will not only prevent the spread of fish diseases but also assist the rearing of brooders and flood control (Fig. 10.6).
Open ditch versus hidden culvert
Inflow and outflow canals may not only be an open ditch but may also be a hidden culvert or a combination of the two. The ditch has many advantages: e.g., simple construction, less labour and material, easy maintenance. However, it occupies a large area of land, obstructs traffic, and loses a large amount of water. The hidden culvert also has many advantages: e.g., it occupies a small area of land, does not obstruct traffic, and loses only small amount of water; however, its construction requires a large financial investment. For the sake of convenience, several maintenance wells should be built at intervals along the channel to avoid the accumulation of silt.
Fig. 10.4. Sectional view of an inlet lock.
Source: Chinese freshwater fish culture editorial board, 1982.
Fig. 10.5. Sectional view of an outlet lock.
Source: Chinese freshwater fish culture editorial board, 1982.
Fig. 10.6. Plane figure showing opposite inlet and outlet type ponds.
Based on the level measurement, the area of fish ponds, and the depth of excavation, the volume of earthwork can be calculated. The amount of excavation should be approximately equal to the amount of filling. The excavated soil should be piled as near as possible to the fill site. This will shorten transportation time and save labour. Therefore, the excavation and filling work should be well coordinated. In balancing the earthwork, if the soil excavated is more than the required fill, it is appropriate to decrease the size or depth of the fish ponds or to increase the stocking area or the height of the weir.
Before implementing any corrective measures, the reason for the leakage must be determined. If the pond bottom or dike contains sand or grit soil, which may cause pond leakage, spread clay soil on the pond bottom; it will be evenly distributed by the inlet water. The clay particles will enter the cracks on the pond bottom during the leakage, plugging the cracks. In certain countries, about 10 m3 / ha of cow dung is spread on the pond bottom a few times; this greatly controls leakage by blocking the soil pores. If the leakage is due to poor construction of the pond dike, compacting of the soil may stop the leaking. If the leaking persists, spread heavy clay soil or turn over the dike for rebuilding until the leakage stops.
Improvement of Acid Soil
Acid soils are common in many parts of the world, e.g., lateritic soil in the tropics, humic soils in the temperate zone, and acid sulphate soils in Southeast Asia (“coastal mangrove soil,” pH < 3). In the Philippines, there are about 100,000 ha of fish ponds on acidic soil; the fish yields are very low. Acidic soil can be regulated with quicklime (Ca (OH)2) or limestone (CaCO3). However, the feasibility of this method depends on the local economic conditions. According to Swingle (1961), practical experience has shown that soils of pH 5 require approximately 2 t/ha of limestone; those with pH 4, 4–6 t/ha.
Newly dug fish pond often contain heavy metals that could harm fish growth and cause “body-curved disease” of fry. Therefore, in the first 2 years, it is better to farm 2-year-old fingerlings and adult fish. If the new ponds are to be used to nurture fry, the water should be changed before stocking the fry to wash away the elements that are harmful to the fry.
I. Ichnographical Drawing with a Theodolite
Within a given area designed for a fish farm, set several points where a theodolite is used for making measurements of horizontal angles and sight distances. Draw an ichnography and calculate the land area.
Selected land area: 25–30 mu.
Based on the shape of the area, set several points as point 1, 2, 3, … n with numbered stakes as indicators.
Place the theodolite at point 1, put the horizontal level at 0°, and point the axis of the telescope toward true north. Record the readings and run the telescope clockwise towards point 2; record the reading and calculate the magnetic bearing of point 2.
Set a leveling rod at point 2 and theodolite at point 2. Write down the reading of the lower and upper stadia hairs. Calculate the distance between points 1 and 2. See Figures 10.7, 10.8 (Shanghai Fisheries College, 1961).
Turn the telescope clockwise toward point n and record the reading to calculate the azimuth of angle 1.
Set the leveling staff at point n and use the same method as in step 4 to calculate the distance between points n and n-1.
Move the theodolite to point 2, level and centre it and repeat steps 4, 5, and 6 to calculate the distance between points 2 and 3 and between points 1 and 2 and the azimuth of angle 2, etc. See Fig. 10.9.
An example is shown in Table 10.1.
|Fig.10.7||A1 A2||upper stadia hair||Fig.10.8.||l||sight distance between point A and point B|
|B1 B2||lower stadia hair||F||focal point|
|P||scale distance between point a and point b||N||centre of the instrument|
|D||distance between N and the rod|
Fig. 10.9. Magneic azimuth.
Fig. 10.10. Area calculation.
Table 10.1. Measurement record form.
|Point of origin||Measured point||Compass reading||Horizontal azimuth||Sight distance reading|
|1||2||00340||Lower stadia hair, 2.044|
|upper stadia hair, 0.963|
|sight distance, 1.081|
|Horizontal distance, 108.1 (m)|
|Lower stadia hair, 2.143|
|upper stadia hair, 0.429|
|sight distance, 1.714|
|Horizontal distance 171.4 (m)|
Calculation and correction of angle deviation
In theory, the total amount of interior angles of a polygon should be as follows:
Σβ = (n - 2) 180°
When n represents the number of interior angle in a polygon or within a closed line and β represents the interior angle. In practice, however, the sum of the interior angles measured σβ, is often not equal to the sum, σβ, because of errors in measurement. The difference between the two is called the closed difference of the angles;
f = Σβ—Σβ
First, we must calculate whether f is within the range of allowable error, which is different in different instruments. If a theodolite is within 6' or 15', the allowable closed error of the angles is ± 25 or 45. If the error is beyond the allowable range, the reason must be found. If f is less than the allowable range, adjustment is made: the error with the opposite sign, is added to each interior angle. In theory, the total corrected angles should be almost the same as σβt.
Land area calculation
The ichonograph that is drawn can be divided into a number of triangles, squares, or trapezoids (Fig. 10.10). The side parameters are measured with a tape measure.
II. Elevation Measurement with Leveling Instrument
Based on the ichnographical measurements, typical points are selected for elevation measurements for design and calculation of fish ponds and earthwork.
At the practical site, several points are selected according to topographical features. Elevation should be measured on the basis of the closest national standard sea level point. If there is none, a hypothetical point can be set as a standard to establish an independent system. Then, from this hypothetical point of origin, the elevation of each point can be measured.
Direction is set with a theodolite and a tape measure is used to calculate distance. In general, there is a survey point every 20 m. These points are marked with numbered stakes and are called elevation control points. The number of these points can be changed in designing and constructing the fish ponds based on the topographical features.
The leveling instrument is placed in a wide sighted view. The leveling staff is set on each control point (Fig.10.11) and the elevation of each point is calculated (Table 10.2).
Table 10.2. Elevation measurement with leveling instrument.
|Control point||Reading on leveling staff no.||High|
III. Design and Layout of an Integrated Fish Farm
Based on the practical work done with Fieldwork Guides I and II and the instructor's lecture, an integrated fish farm can be designed.
Design an integrated first-livestock-crop farm with herbivorous fish as its major species (60 per cent fish yield).
Design an integrated fish farm with a plankton-feeding fish as its dominant species (60 per cent fish yield).
Fig. 10.11. Elevation measurement.
Note the following:
Net yield is about 200 kg/mu.
The fine feeds needed by the livestock are provided by the market.
Fry are provided by the market and fingerlings are nurtured by the farm.
Calculate the area of the fish ponds, the width of the dike crown, the position and structure of the inflow and outflow canals, the amount of soil to be excavated and to be filled, the area of the fodder crop land (including dike crown and slopes). Determine the positions and number of livestock and poultry houses on the farm.