FISH POND EVALUATION PROCEDURE

Fish Pond Evaluation

Criteria used for fish pond evaluation

1. WATER SUPPLY

Adequate supply of good quality of fresh and salt-water must be available year round in the site. Good quality water suitable for fish culture is rich in oxygen, nutrients and free from pollutants.

Freshwater is important for mixing with sea water to maintain salinity level especially in the dry season when evaporation is rapid. Freshwater is also necessary for the daily use of the workers in the fish farm.

2. SOIL CHARACTERISTICS

Many soil characteristics, especially those related to texture, determine its suitability for fishpond purposes. Soil texture refers to the relative proportion of sand, silt and clay content of the soil. Table 1 below shows the different soil classification based from the U.S. Department of Agriculture Classification System.

Table 1
Texture and textural name of the three main types of soil

Common name	Texture	Basic soil textural class name
Sandy soils	Coarse	Sandy; sandy loam
Sandy soils	Moderately coarse	Sandy loam; fine Sandy loam
Loamy soils	Medium	Very fine sandy loam
Loamy soils	Moderately fine	Loam, silty loam Silt
Clayey soils	Fine	Sandy clay; silty clay; clay; clay loam; sandy clay loam; silty clay loam

Areas suitable for fish production must possess properties which allow for the economical construction of dikes, efficient growth of fish food, extended water holding and load carrying capacity and favourable chemical properties.

(a) Desirable soil texture for ponds.

Soils belonging to the following textural classification are desirable for fishpond development: clay, clay loam, silty clay loam, silty loam, loam and sandy clay loam (Dureza, 1982).

Clayey soils are preferable because they are superior material for diking and holding water. They have good compaction characteristics and low permeability. A very simple general rule can be followed: As a clay content of the soil decreases, its suitability for fishpond construction also decreases. This is illustrated in Table 2

Loamy soils are also recommended. They have good organic matter content which favour the culture and growth of natural fish food.

(b) Determination of soil texture.

Soil texture can be determined by various methods ranging from the sophisticated mechanical and laboratory methods to the simple practical and field methods. The following sections outline some of these methods.

(i) Mechanical method of determination of soil texture

The amount of each soil separate (size fraction of sand, silt and clay) in a soil mixture determine its texture. The popular Bouyocous mechanical test is a reliable method of determining the amount of each soil separate in the soil through laboratory tests. The test results are then compared with a soil triangle (Fig.2.3) to determine the textural name.

(ii) Field identification of soil texture

There are three practical field identification methods to determine soil texture. These are the feel method using a modified soil triangle, feel method (alternative) and ball method.

Table 2
Relationship of soil classes and suitability for dike material (after BFAR-UNDP/FAO, 1981)

Class	Permeability	Compressibility	Compaction	Suitability
Clay	Impervious	Medium	Fair to good	Excellent
Sandy clay	Impervious	Low	Good	Good
Loamy	Semi-pervious	High	Fair to very poor	Fair
Loamy	to impervious	high	Fair to very poor	Fair
Silty	Semi-pervious	Medium	Good to very poor	Poor
Sandy	to impervious	to high	Good to very poor	Poor
Peaty	Pervious	High	Good	Poor
Peaty		Negligible		Very poor

TOPOGRAPHY OF FISH POND SITE

Topography refers to the “lay of the land” or the changes in the surface elevations of the ground whether flat, rolling or sloping, undulating, and hilly. Fishpond design, layout and specifications are made largely in accordance with the land topography.

A suitable site for fishpond has a topography that can be converted into a pond economically. The cost of construction can be greatly reduced if the surface features of the land are used to advantage.

Flat coastal swamplands whose elevation are within the range of ideal pond bottom elevation are preferred for brackishwater pond culture. In such areas, excavation or filling are at a minimum, if any. Sites with rolling topography or those with elevations varying from lower than MLLW (00 tidal datum) to 4–5 m high must be avoided as these will be too costly to level (de los Santos, 1980).

Denila (1980) describes four zones in the coastal edge as probable sites for fishpond

(a) Zone A. Marginal lands along edges usually planted to lowland rice but generally unproductive due to salt water seepage can be converted into fishpond by lowering the elevation through excavation. These are usually productive as fishponds because of good soil quality. The cost of excavation can make these areas relatively more expensive to develop due to their high elevation.

(b) Zone B. The elevation is generally high with occasional earth mounds along the edges but can be reached by tides. High dikes not necessary but development cost may be expensive if a big portion of the area needs excavation.

(c) Zone C. This area is within the ideal range of pond bottom elevation, thus excavation cost is less. However, extreme acidity may occur because of the presence of vegetation that contributes to acidity.

(d) Zone D. The elevation is low or just a little higher than the 00 datum (MLLW). It is very exposed to wave action which may require expensive big dikes and wave protection structures. No acidity problem, hence, may be ideal for shrimp culture.

2.1 Criteria used

2.1.1 Water supply

Adequate supply of good quality of fresh and salt-water must be available year round in the site. Good quality water suitable for fish culture is rich in oxygen, nutrients and free from pollutants.

SOIL CHARACTERISTICS OF FISH PONDS

Many soil characteristics, especially those related to texture, determine its suitability for fishpond purposes. Soil texture refers to the relative proportion of sand, silt and clay content of the soil. Table 3 below shows the different soil classification based from the U.S. Department of Agriculture Classification System.

Table 3
Texture and textural name of the three main types of soil

Common name	Texture	Basic soil textural class name
Sandy soils	Coarse	Sandy; sandy loam
Sandy soils	Moderately coarse	Sandy loam; fine Sandy loam
Loamy soils	Medium	Very fine sandy loam
Loamy soils	Moderately fine	Loam, silty loam Silt
Clayey soils	Fine	Sandy clay; silty clay; clay; clay loam; sandy clay loam; silty clay loam

(a) Desirable soil texture for ponds. Soils belonging to the following textural classification are desirable for fishpond development: clay, clay loam, silty clay loam, silty loam, loam and sandy clay loam (Dureza, 1982).

Loamy soils are also recommended. They have good organic matter content which favour the culture and growth of natural fish food.

(b) Determination of soil texture. Soil texture can be determined by various methods ranging from the sophisticated mechanical and laboratory methods to the simple practical and field methods. The following sections outline some of these methods.

(i) Mechanical method

(ii) Field identification

There are three practical field identification methods to determine soil texture. These are the feel method using a modified soil triangle, feel method (alternative) and ball method.

Table 4
Relationship of soil classes and suitability for dike material (after BFAR-UNDP/FAO, 1981)

Class	Permeability	Compressibility	Compaction	Suitability
Clay	Impervious	Medium	Fair to good	Excellent
Sandy clay	Impervious	Low	Good	Good
Loamy	Semi-pervious	High	Fair to very poor	Fair
Loamy	to impervious	high	Fair to very poor	Fair
Silty	Semi-pervious	Medium	Good to very poor	Poor
Sandy	to impervious	to high	Good to very poor	Poor
Peaty	Pervious	High	Good	Poor
Peaty		Negligible		Very poor

TOPOGRAPHY OF FISH POND SITE

Denila (1980) describes four zones in the coastal edge as probable sites for fishpond (Fig. 2.7).

2.1.5 Type and density of vegetation

Coastal fishponds in the tropical and sub-tropical zones are constructed on tidal lands, river estuaries, bays and sheltered coasts. The vegetation present in these areas are varied depending on the land elevation and soil type. However, mangrove trees pose serious concern to fishpond development because of their extensive rooting system.

Fig. 2.7 The four zones in typical swamps as probable sites for fishpond (After Denila, 1980)

2.1.6 Climatic and watershed conditions around the site

The climatic factors largely affecting site selection and fishpond design are wind and rainfall. The direction of prevailing wind is reckoned with in designing the layout of fishponds as it generates erosive wave action against the dikes. The wind energy also causes natural water circulation and aeration in the pond. For rainfall information, maximum intensity, duration, frequency and annual distribution within the watershed are important as these are associated with flooding that would affect the site.
The land area that surrounds or lies above the site is referred to as a watershed. This drains its collected surface runoff through a river, river system or body of water causing flood water which could affect the site. The volume of flood water or runoff are affected by the rainfall and soil characteristics, type of vegetative cover, topography, and area of the watershed. Much higher rate of runoff can be expected in a watershed that has high rainfall intensity and duration, clay or heavy-textured soil covered with less vegetation or grassland, high slopes and covering large area than a watershed characterized with low rainfall intensity and short duration, loamy or coarse-textured soil that is forested with flat or gently rolling slope and small area.
The pattern and recurrence of maximum height of flood waters in the site must be determined. These information can be obtained from the rainfall or flood records of appropriate agency for each country. It is common, however, that the sites are located in remote areas where such records may not be available. In this situation, rough information on flood may be obtained from knowledgeable residents who have seen the recurrence of floods for years in the area.
The design of fish farm should be based on a flood height with recurrence interval of 10–15 years. Longer recurrence interval of 25 or 50 years means much higher flood level and hence, much bigger dikes and structures which makes the design uneconomical or impractical. It would be more economical to repair damaged fishponds (designed for 10–15 years flood) during the sudden occurrence of say 25 years or longer term floods than to design the entire farm for such floods.

2.1.7 Other criteria

There are other factors which are significant in fishpond site selection. These are equally as important as those previously mentioned and likewise require the same careful evaluation during the survey.

a. Accessibility. This is important for the transport of construction equipment and material, and for production inputs required for daily operations. Transporting costs can considerably increase if materials are manually carried through long distances. It is better if the site is accessible throughout the year by means of land and water.

b. Availability of labour. The cheapest sources of labour are those which can be provided by the local residents, or people living within or near the area. It is important that the customs and tradition of local labourers are known. The pattern of labour distribution and utilization should be considered as this is important in preparing the calendar of activities. In the Philippines, it is generally difficult to obtain enough labour during the rice planting and harvesting season or during milling season for sugarcane.

c. Availability and cost of material. In fishpond production, it is important that critical production inputs such as fishseeds, fertilizers, pesticides and other related materials are readily available when needed. For some inputs, especially inorganic fertilizers, the supply is restricted and the cost is uncontrolled for non-agricultural uses. Other inputs like organic manures are difficult to obtain, or may be available only at certain times of the year. If purchase in bulk is necessary, then storage space must be available. If material is to be imported, restrictions and corresponding costs must be known.

d. Availability of marketing outlets and prices. Aquaculture products are highly perishable. Immediately upon harvest, products must be disposed of to maintain good quality and for better prices. If marketing outlets are located at a distance, larger quantities must be harvested and transported requiring some post-harvest marketing practices. If so, then the required support facilities especially ice-making plants must be available.

e. Availability of credit and technical assistance. Fishpond operations require high initial capital investment. In this respect, credit at reasonable terms play a major role in providing the needed cash outlays.

Technical assistance may be obtained from government extension services, public or private university research stations and lending institutions. The services rendered by these agencies are important especially in cases of emergency.

f. Pattern of land and water use. It is important to assess the pattern of land and water use in the area to determine the impact of this on the project. Activities such as navigation, fishing, industries, public utilities, recreation and nursery areas must be included in the overall assessment. It is best that a complementary rather than competitive relationship between these various uses and the project be established.

g. Peace and order situation. Good peace and order conditions at site are favourable for both public and private interests.

2.2 Making the decision

The success of coastal fishpond operations depends not only on the general site suitability for fish production but also on other related factors such as input and labour availability, accessibility, marketing considerations and others. Site selection not only involves the determination of desirable physical, chemical and biological factors. It is also important in providing valuable information in the preparation of the overall design and layout of the facility, engineering modifications to be made and the choice of management practices appropriate for the given site.
It is important to remember that there is no site that possesses all the desirable characteristics for fishpond operation. Moreover, no two sites are exactly identical with one another. Hence, the degree of suitability of various sites evaluated vary from one area to another.

2.2.1 Method of evaluation

The evaluation of the suitability of fish farm sites involves a detailed survey of both technical and non-technical aspects, and the processing of information gathered in order to make the final selection.

a. The survey. If possible, the survey should be comprehesive to cover aquacultural, ecological, engineering, socio-economic, management and financial aspects. As a standard practice at least two surveys should be conducted during the year—one each during the dry and rainy seasons. It is important to evaluate the prevailing conditions for different seasons because there are factors that change at different times of the year. A wrong judgement could be made in the selection if only one survey is conducted.

Conducting the survey can be a costly, laborious and time-consuming exercise if the proper steps, procedures and preparation are taken for granted. Adisukresno (1982) recommends the following to save money, time and effort:

i. Sufficient and complete questionnaires or forms should be prepared before leaving for the survey;

ii. Questionnaries must be properly and completely accomplished during the survey;

iii. An itinerary or travel schedule should be prepared;

iv. Only trained or capable personnel should conduct the survey;

v. Needed field equipment should always be put together and brought along;

vi. A list of people to be the met and purpose of meeting should be prepared ahead of time.

b. Processing of information. Data and information collected during the survey are combination of quantitative and qualitative; thus, it is very difficult to arrive at a general decision. The most commonly used method of deciding the suitability of sites from among a number of prospective sites surveyed is the point and ranking system.

c. Applying the point and ranking system. Under this system, all data and information are transferred into numbers or assigned numerical points or scores. The scoring could be from 1 to 10 or from 1 to 100. A site with the most desirable characteristic for a certain criterion is assigned the highest score, the lower the value, the less ideal or desirable site becomes and vice-versa. For example, in evaluating the accessibility, if a road leads right into the central area, a score of 10 can be given to this site; if reached within walking distance, 9; and if reached along across a river or creek, 8 or less. With regard to the type of vegetation, presence of Nypa sp. can be ranked lowest; mangrove with Avicennia sp. can be ranked highest, and so on.

2.1 Criteria used

2.1.1 Water supply

Adequate supply of good quality of fresh and salt-water must be available year round in the site. Good quality water suitable for fish culture is rich in oxygen, nutrients and free from pollutants.

2.1.3 Soil characteristics

Many soil characteristics, especially those related to texture, determine its suitability for fishpond purposes. Soil texture refers to the relative proportion of sand, silt and clay content of the soil. Table 2.2 below shows the different soil classification based from the U.S. Department of Agriculture Classification System.

Table 2.2
Texture and textural name of the three main types of soil

Common name	Texture	Basic soil textural class name
Sandy soils	Coarse	Sandy; sandy loam
Sandy soils	Moderately coarse	Sandy loam; fine Sandy loam
Loamy soils	Medium	Very fine sandy loam
Loamy soils	Moderately fine	Loam, silty loam Silt
Clayey soils	Fine	Sandy clay; silty clay; clay; clay loam; sandy clay loam; silty clay loam

Loamy soils are also recommended. They have good organic matter content which favour the culture and growth of natural fish food.

(i) Mechanical method

(ii) Field identification

There are three practical field identification methods to determine soil texture. These are the feel method using a modified soil triangle, feel method (alternative) and ball method.

Table 2.3
Relationship of soil classes and suitability for dike material (after BFAR-UNDP/FAO, 1981)

Class	Permeability	Compressibility	Compaction	Suitability
Clay	Impervious	Medium	Fair to good	Excellent
Sandy clay	Impervious	Low	Good	Good
Loamy	Semi-pervious	High	Fair to very poor	Fair
Loamy	to impervious	high	Fair to very poor	Fair
Silty	Semi-pervious	Medium	Good to very poor	Poor
Sandy	to impervious	to high	Good to very poor	Poor
Peaty	Pervious	High	Good	Poor
Peaty		Negligible		Very poor

2.1.4 Topography of the site

Denila (1980) describes four zones in the coastal edge as probable sites for fishpond (Fig. 2.7).

2.1.5 Type and density of vegetation

Fig. 2.7 The four zones in typical swamps as probable sites for fishpond (After Denila, 1980)

2.1.6 Climatic and watershed conditions around the site

2.1.7 Other criteria

g. Peace and order situation. Good peace and order conditions at site are favourable for both public and private interests.

2.2 Making the decision

2.2.1 Method of evaluation

i. Sufficient and complete questionnaires or forms should be prepared before leaving for the survey;

ii. Questionnaries must be properly and completely accomplished during the survey;

iii. An itinerary or travel schedule should be prepared;

iv. Only trained or capable personnel should conduct the survey;

v. Needed field equipment should always be put together and brought along;

vi. A list of people to be the met and purpose of meeting should be prepared ahead of time.

2.1.6 Climatic and watershed conditions around the site

2.1.7 Other criteria

g. Peace and order situation. Good peace and order conditions at site are favourable for both public and private interests.

2.2 Making the decision

2.2.1 Method of evaluation

i. Sufficient and complete questionnaires or forms should be prepared before leaving for the survey;

ii. Questionnaries must be properly and completely accomplished during the survey;

iii. An itinerary or travel schedule should be prepared;

iv. Only trained or capable personnel should conduct the survey;

v. Needed field equipment should always be put together and brought along;

vi. A list of people to be the met and purpose of meeting should be prepared ahead of time.

The evaluation procedure employed for fish ponds is basically centred on location, serviceable, durability and profitability.

The location for earthen pond is limited to areas where there is clay soil and underground water of a flowing stream. It is therefore sited in swampy areas where clean fresh water is available and must be free of any industrial emission that can cause pollution unlike vats and concrete ponds that can be sited anywhere regardless of location.

The strength, durability and serviceability of earth ponds and wooden ponds (vats) can not equate that of a concrete fish pond with up to ten years of service before repair or maintenance if properly designed.

Nigeria is Africa’s most populous nation, yet suffers a lot of food insecurity and there is an increasing demands for the fish food particularly catfish within and outside the country. The use of reinforced concrete design model for catfish has rarely contributed to the country’s economy due to its high initial cost of construction.

However, an alternative design model/method is necessary to boost the country’s economy through fish farming and the related fish product. There is therefore need to source for an alternative method of pond fishery that is both effective and economical.

FISH POND EVALUATION PROCEDURE