An integrated fish farm is a multi-trade integrated production complex. There are close ties among all the trades, all the management departments and between the fish farm and the outside of the farm. These ties display a series of proportional relationships. The main task of planning and management on an integrated fish farm is to adjust these proportions according to certain conditions and to get a comprehensive balance by quantitative analysis ao as to obtain maximum economic returns.

For the sake of brevity and practicality, we just introduce the principal statistical methods, omitting the theoretical description. Besides, here is exe point we must emphasize, that is, owing to the complexity of integrated fish farming, some parameters have not been gained; some data are not so accurate; the proportional relationships mentioned in this chapter should be adjusted during execution of the programme.

The following are the principal calculating methods of requirements of fish, livestock and crop based on the final produce of the farm.

1. Formulas of Relationships

1) Fish farming

(1) Fish yields and stocking amount

(i) Gross yield of grow-out pond

Where | N_{i} : | Stocking quantity of each spp. in different sizes in polyculture (tail/mu) |

S_{i} : | average weight of fish of each spp. in different sizes (kg/tail) | |

T_{i} : | times of gross weight gain of each spp. in different sizes | |

R_{i} : | survival rate of each spp. | |

S_{i}: | size of each spp. harvested |

(ii)

S^{1}: | target size of a certain species at transference |

N : | stocking quantity (tail/mu) |

R : | survival rate (%) |

(iii) Stocking quantity of a certain species (tail)

S : | stocking size (kg/tail) |

T : | times of weight gain |

from (a), the size of fingerlings can be known by

(iv)

The above-mentioned formulas can be applied to the yearling and 2 year-old fingerling ponds. In order to make stocking plans or forecast the yields, farmers not only should understand the relations between the items but also should understand the dove tail part of different sizes in different stages and general survival rate and weight gain of fish in different sizes.

EX. 1 One fish farm has 100 mu of grow-out ponds, it practises polyculture of various species in different sizes. The target gross yields, sizes of Grass carp and Silver carp are formulated below. The survival rates of Grass carp and Silver carp according to the records are also listed in the table. The stocking quantity and stocking sizes of Grass carp and Silver carp fingerlings are calculated by

Table

species | size (kg/tail) | gross yield (kg) | survival rate (%) | times of gross weight gain |

Grass carp | 1.5 | 60 | 85 | 4 |

0.4 | 40 | 80 | 12 | |

Silver carp | 0.6 | 60 | 95 | 3.5 summer harvest |

0.5 | 45 | 90 | 5 |

From | we can get total number of Grass carp and Silver carp (tail/mu). From |

The calculated results are shown in the following table.

species | size (kg/tail) | quantity (tail/mu) | weight (kg/mu) | total tail | amount in 100mu weight (kg) |

Grass carp | 0.32 | 47 | 15.04 | 4706 | 1504 |

0.027 | 125 | 3.38 | 12500 | 338 | |

Silver carp | 0.163 | 105 | 17.10 | 10500 | 1710 |

0.09 | 100 | 9 | 10000 | 900 |

With the same method, the yearling can also be calculated from 2-year-old fingerling and summerling from yearling. If the survival rate is 80%, the times of gross weight gain are 10 and 45 respectively. The quantity of yearlings = 4706 - 80% = 5883 tails.

The size of yearlings = 1504 - 5883 = 0.026 kg/tail.

The size of summerlings = 12500 - 80% = 15625 tails.

The size of summerlings = 388 - 45 - 12625 = 0.5 10^{-3} kg/tail.

(v) target quantity of fry (unit: 10,000)

where | N': | number of summerlings (unit: 10,000 fish) |

R : | Survival rate of summerlings from fry |

(vi) Target number of fertilized eggs (unit: 10,000 eggs)

where, | N': | target number of fry (unit: 10,000 tails) |

R : | hatching rate |

If you want to calculate the target spawning quantity, N' should be changed to target fertilized quantity, R changed to fertilizing rate.

(vii)

where, | W: | target body weight of female brooders (kg) |

N: | target spawning quantity | |

n: | average spawning quantity per kg of female brooder |

(2) Area of ponds

The pond areas required for each stage from summerlings to grow-out are calculated as follows: the target gross yields (polyculture) are divided by per-unit gross yield (polyculture); from summerlings to yearlings, the number is calculated out on the basis of tails. Fry nurturing needs no special ponds. The area of brooder rearing pond can be obtained from the total weight of brooders divided by stocking amount per mu.

(3) Fish feeds

(i) Calculation standard

In most cases, fish ponds in China are applied with whatever feeds available, a compound one. The formula of calculation is more complicated and it leads inconvenience to scientific management. In practice, a kind of feeds with common use and stable source often serves as a standard of calculation such as barley in southern part of Jiangsu Province or pelleted feeds in certain places. For green fodder, aquatic grass serves as a calculation standard. And then, on the basis of feed sources available and the needs of cultivated spp., the feed amount should be converted into the actual amount of feeds according to the equivalent ratio between actual amount and standard amount.

EX.2 A farm expects 1000 T barley, the department of goods and materials can only provide 50% of it, the rest are substituted by 20% bean cakes, 20% brans and 10% pellets. Evalution: the exact quantity of each substitutes.

Solve: According to the available informations, equivalent ratio between barley and the substitutes is 3/4 for bean cake, 2 for brans, ½ for pellets.

The quantity of bean cake = 1000 × 20% × 3/4 = 150 T.

The quantity of brans = 1000 × 20% × 2 = 400 T.

The quantity of pellets = 1000 × 10% × ½ = 50 T.

(ii) Calculation method

The total requirements of fine feeds are the sum of the fine feeds needed at each growth stage except hatching. The total requirements of green fodder is the sum of the green fodder needed at each growth stage except the periods of hatching and post larva nurturing. The requirements of fine feeds and green fodder are calculated by using the following formula:

A. The requirements of fine feeds at a certain stage

Where, | Y: | target net yields of each species at a certain stage. |

C: | food coefficient of a calculation standard feed fed to each species of food-feeders. | |

R: | Utilization rate of the feed (%) |

In actual production, R is within the food coefficient. To solve the requirements of fry nurturing stage, Y and C represent the number of fry(unit: 10,000) and feeds fed to 10,000 summerlings respectively.

If the fine feeds are used mixing with the green fodder, the feeds have to be calculated as fine feeds and then the same method as EX.2 is used to calculate the quantity of green fodder.

EX. 3:

A farm expects to gain 2000 kg of Black carp, 6000 kg of herbivorous fish, 2000 kg of Common carp and Crucian carp. If barley is used as a standard feed, how much is required then? If the barley provided is only 50%, the rest come from rye grass and sudan grass, then how much of the grass?

Solve: Based on the information, the barley's coefficient in rearing the above-mentioned species are 4, 3, 3.5 respectively. Total requirement of barley = 2000 × 4 + 6000 × 3 + 2000 × 3.5 = 33000 kg

Suppose the annual output of rye grass and sudan grass has been averaged out; their coefficient for herbivorous fish is about 30; Their value equivalent to barley is about 10.

Grass requirements = 33000 × ½ × 10 = 165000 kg

B. The requirements of green fodder at a certain stage

Where, | Y_{g}: | The target net yields of herbivorous fish at a certain stage |

C_{g}: | the food coefficient of a standard green fodder | |

R: | utilization rate of this fodder |

R can be omitted in production because it's within the food coefficient.

When there is a shortage of green fodder, fine feeds are used as supplementary feeds. The deficient number should be converted into the number of fine feeds according to its equivalent ratio.

for example, 1000kg of Sudan grass can be converted into 100 kg of barley. If it is used for herbivorous fish, its equivalent ratio is 10. 1000 kg (Sudan grass) ÷ 10 (equivalent value) = 100 kg (barley).

(4) Manure for fish culture

Total requirements of manures are the sum of manures needed at different stages. If manures applied come from different sources, a kind of manures with common use and stable source serves as calculation standard. The actual amount can be calculated out according to equivalent ratio. The target amount of manure at a certain stage, M is:

M = (Y_{1}-n Y_{2}) C

Where, | Y_{1}: | the target net yield of filtering fish |

Y_{2}: | the target gross yield of feed-eaters | |

n: | net yield of filtering fish which feed on the plankton produced out of excreta of the feed-eaters per unit gross yield. |

However, the rate varies with the species and feeds and ecological factors. Generally, it ranges from 0.2 to 0.6;

C: the manure conversion coefficient of a certain kind of manures to fish flesh

In fact, this coefficient results from many ecological factors and will be obtained in the actual practice in each specific farm. The animal manure takes faeces as standard. The urine should be converted into faeces by certain ratio.

EX. 4

A certain farm is expected to produce herbivorous fish and filtering fish of 15000 kg each in grow-out pond with terrestrial grass to feed herbivorous fish and with livestock manure to fertilize pond water. Now there is about 100,000 kg of pure pig excreta. If the rest is replaced by cowdung, how much will it be needed?

Solve: Based on the experiment, the conversion coefficient of pig excreta and cowdung is 25 and 40 respectively. Suppose 0.5 kg of filtering fish can be raised by virtue of plankton produced by excreta of herbivorous fish. We use pig excreta as a standard.

M = (15,000 – 0.5 × 15000) × 25 = 187500 kg.

Subtract 100,000 kg of pig excreta; cowdung needed is as follows:

(5) The area of crop production

Ref Chapter 7 section 2. Calculate grass planting area only because the economic returns of planting manure crop and fodder crop are poorer than that of planting grasses for fish farming.

(6) The number of animals matched with fish farming and the construction area of animal shed.

After total requirements of manures are worked out, the requirements of different kinds of manures can be allocated and calculated according to the local conditions and so the numbers of different animals can be calculated out.

(i) Number of a certain animal raised in its production period.

Where, | M = | The requirement of a certain animal manure (kg) |

m: | the amount of excreta of one animal during a production period (the urine should be converted into faece) | |

c: | periods of animal raising in one year (the time can be overlapped) |

(ii) The construction area of animal houses

Where, | N: | total number of a certain animal raised in the whole year |

C: | unoverlapped raising periods of a certain animal in one year. For example, fattening pigs need 5–6 months, so there will be 2 periods in one year. | |

s: | average construction area for one animal. If the quantity is not the same in different raising period, use the following formula: |

S = Ns

Where, N = the greatest number in a batch (See Fig. 8–4–1)

2) Drawing up the model diagram of plans

(See Fig. 8–4–2)

2. Appraisal of Economic returns of Integrated Fish Farming

2.1. Appraising methods and procedures

1) Methods

(1) The methods of material collection

(i) Surveying method

In term of scope, investigation can be divided into general surveying, sampling and typical surveying. In terms of form, live coverage and questionaire through correspondence. Investigation through various methods can get better results, nevertheless, general surveying combining with typical surveying are commonly practised.

Before investigation, the objective, contents and targets ought to be fixed; the precis of investigation be designed; the table of investigation be drawn up and then the surveying can be conducted deeply and widely as planned.

(ii) Experiment method

Due to the weak points of investigation, the trial and error procedure should be performed for complement and verification. Experiment on the site should be held before any new decision on technical measurements is adopted. In order to give a correct appraisal, it's necessary to get technical and economic data as complete and accurate as possible.

(2) Data analysis and processing

There are several methods of data analysis:

- Comparative analysis
- Cut and try
- marginal analysis
- regressional analysis
- linear analysis

(3) Selecting the best after the appraisal

After the appraisal, the best plan can be selected in line with the local conditions and enterprise capabilities by using the abovementioned methods and overall & systemetical analysis.

2) Procedure

The procedure of appraisal of economic returns of integrated fish farming technique is as follows:

(See Fig. 8–4–3)

2.2. The main indicators of economic returns of integrated fish farming techniques

The indicators of economic returns of integrated fish farming techniques is a measurement of the farming management. Due to the complexity of integrated fish farming, any individual indicator can't represent the whole farming activities. Therefore, it is a must to introduce a series of indicators for the general analysis. The common indicators practised in both research and the actual production are as follows:

1) The indicators of economic analysis

(1) Production indicators

It mainly reflects the productivity and the level of technical and economic management. This production is the yield indicator in kind (material object). In an integrated fish farm, however, there are varieties of produce, but they can't be simply added one another & they must be changed into the protein production or energy output for easy calculation.

There are 2 kinds of production: total production and per-unit yield. The total production refers to the total amount of one kind of products such as fish, milk or egg, etc. in a year. The per-unit area or volume yield refers to fish and crop yields in one unit land area or unit surface or unit water body while the yields of husbandry and poultry are calculated based upon the number of head. The formula is as follows:

The per-unit area yield indicates the effects of utilization of land or surface and the animal production capabilities. If the other factors do not change, the higher the per-unit area yield, the better the economic returns.

For the per-unit area fish yield, the methods of calculation varies a great deal in many places. In general, the average per-unit area yield should be as follows: the total yield is divided by the whole pond area including fingerling rearing ponds or the yield can be calculated out as yield of grow out pond and yield of and fingerling pond. Pond area means the area of a fish pond excluding the pond dyke. In China, the pond fish culture employs the polyculture system. Different techniques are practised in different stocking models, the yields of each species differs, thus, resulting in different economic benefits. So in appraisal, per-unit area yield for each specific species is necessary for calculation.

Production indicators also include commodity indicators. This refers to the products entering the circulation. The percentage of commodity in total yield is called commodity rate. These two indicators represent the contributions (in other wprds, social benefit) made by the labourer in an integrated fish farm.

Total yield or per-unit area yield can be divided into gross and net yield too. The gross yield includes the input weight of fry or young animal while the net yield does not. So the net yield indicators can accurately represent the production level.

(2) Output value and income indicators

(i) There are 2 kinds of output value: total output value of the farm and that of any specific trade. The former is a total amount of the product value of all trades. The latter is a total amount of the value of each trade such as aquaculture or livestock output value. The total output value reflects measure of value for the final results of the farm management. The output value of a certain product equals product of the yields multiplied by its price. There are two kinds of prices which are used to calculate output value: current price & constant price. The current price is the local price of the year when the product is produced. The constant price indicates the fixed price in a certain year as the basis of output value calculation in a certain period which is also called comparative price. The constant price fixed in 1980 serves as a standard for appraisal of economic returns of integrated fish farming techniques.

(ii) Total income

It indicates the revenues which can offset the expenditures, wages in kind and in cash. It is different from the total output value because the latter includes weight gain of both fingerlings and young animals which are unsold while the revenues refer to the income of sold products. The total output value excludes non-productive income while the revenues include the interests and rent of non-productive income etc. The total output value is evaluated by using comparative price while the revenues by using actual price.

(iii) The per-unit area output value and income

The total output value and revenues of aquaculture, crop and animal husbandry are respectively divided by the stocking area, cultivated area and head of reared animals to obtain the accurate per-unit area output value and income of fish, crop and animal, per-unit animal output value and income. If the other factors do not change, the higher the indicators, the greater the economic returns.

(3) Cost indicator

The production cost of integrated fish farming is the sum of embodied labour and living labour, that is, the sum of total expenses of production means and wages measured in value. It's a synthetic indicator of labour consumption.

Production cost: There are 2 kinds-the total cost of the farm and the total cost of each trade. The total cost of aquaculture includes the costs of fingerlings and food fish. For comparison, the cost indicators are calculated according to the following formula:

Per-unit area production cost of fish or crops

Per-unit product production cost of a certain product

Per-unit product output value cost

The three indicators of per-unit area, per-unit product and perunit output value cost can accurately reflect the farming consumption. They are important indicators in appraising the economic returns of integrated fish farming techniques. Therefore, the lower the cost, the greater the economic returns.

(4) Net output value and net income indicators

(i) Net output value

It refers the new value created by the producers, that is, the total output value deducts all the value consumed in the operating process. The production results can be clearly shown. The net output value is calculated according to the constant price. It is a remainder of the revenues substracted by the total production cost. For state-owned fish farm; it includes tax and profit; for the collective or individual farms, the operating cost excludes the labour payment so it is actually an incomplete cost. Thus, the net income includes the taxes and gross profit which contains the accumulation funds, welfare funds and bonus. Owing to the difference of the collective farm and individual farm, the net income can be calculated according to the same standard or compared directly with gross profit.

The net output value and net income indicators are operating results and also it is a synthetic indicator which can accurately reflect economic benefits. The following three indicators are often adopted to appraise the net output value and net income.

Net output value or net income per-unit area

Net output value of per-unitproduct

Net output value of cost (net income)

In the last formula, if the numerator and the denominator refer to the net output value and production cost of the farm or a trade or a product respectively, the percentage shows the net output value rate of cost respectively; if the numerator refers to the profit, the percentage will show profit rate of cost.

The three indicators stated above are the important factors in appraising the farm activities and they can accurately reflect farming consumption and results and utilization rate of all kinds of the natural resources. The higher the data, the greater the economic benefits.

(5) Labour productivity

It refers to the produce and output value which per-unit living labour creates on an integrated fish farm. The formula is as follows:

There are four indicators commonly used for comparison between living labour consumption and farming achievements:

(i) Net output value created by each labourer

This formula can be applied on a farm, a certain trade or a certain product. In the state-owned farm, the labourers are quite stable whole in the collective or individual farms, there is a great change for labbourers. In actual apprasial, 300 work days are generally considered to be one man-year. This accurately reflects the new contribution to the society by each labourer, excluding the effects of embodied labour on labour productivity. The higher the value, the greater the economic benefits.

(ii) Net income created by each labourer

(iii) Profit made by each labour

These two indicators have the same functions with the net output value in appraisal.

(iv) The commercial produce contributed by each labourer per annum

An integrated fish farm produces varieties of products, but they can't be simply added one another. In order to analyse the indicator of the whole farm, the measurement form of products should be uniformed e.g. protein. This indicator reflects the social contribution by the labourers

(6) Investment analysis

The following two indicators are commonly used for investment analysis.

(i) Return of investment

If the investment is applied to enlarge the production scale or renovate the old facilities, the average profit per annum should be changed to the increment of average profit.

(ii) Coefficient of returns in investment, which is a reciprocal of the indicator above, reflects the economic returns per-unit investment in quota turnover period. The shorter the turnover, the higher the coefficient, the better the economic returns.

2) Technical Analysis Indicators

(1) The fish growth rate and daily weight gain of animals

(i) The fish growth rate

(ii) Daily weight gain of animal

(2) Times of weight increment

From gross yields and net yields, we'll have gross and net weight increment. The formula: total fish yields of pond divided by the stocked quantity equals times of weight increment. The above-mentioned three technical indicators reflect the growth rate of fish, livestock and fowl under the conditions of different technical measures.

(3) Food coefficient

(4) Conversion rate of food

This indicator is called feed reward, that is, certain quantity of animals is gained out of per-unit quantity feeds.

(5) Manure conversion coefficient

This indicator is new concept summerized out of the actual practices of integrated fish farming. This indicator varies with manure quantity, ecological conditions and technical management. The above-mentioned indicators represent the relationships between input of feeds and fertilizers and output of fish, livestock & fowl.

(6) Protein or energy utilization rate

From another aspect, it represents the relationships between the input and output. Among this formula, manure has nothing to do with other factors except fish. Energy utilization rate is used in appraising the economic returns of integrated fish farming compound ecological system techniques. Thus, various embodied labour and living labour should be converted into energy.

(7) Feed equivalent ratio

It refers to the ratio between new feeds or substitutes coefficient and standard feeds coefficient. It indicates the effects of comprehensive utilization.