What Are The Steps In Fish Farming?
Throughout the centuries fish has been an important component of the population’s diet in many parts of the world. Fish catches increased rapidly over the past hundred years due to improved technology, which provided more powerful engines and sonar equipment.
This led to over fishing and caused a worldwide decrease in wild stocks. As a result, the growth in fish catches stopped some 20 years ago. The need to increase fish production by farming became therefore an urgent matter.
The term ‘aquaculture’ covers all forms of cultivation of aquatic animals and plants in fresh-, brackish- and saltwater. Aquaculture has the
same objective as agriculture, namely, to increase the production of food above the level that would be produced naturally. Today, aquaculture is responsible for an ever-increasing share of global aquatic food production, which has increased from 3.9 percent in 1970 to 31.9 percent in 2003.
Methods of fish farming
Fish farming may range from ‘backyard’ subsistence ponds to large scale industrial enterprises. Farming systems can be expressed in terms of input levels.
In extensive fish farming, economic and labour inputs are usually low. Natural food production plays a very important role, and the system’s
productivity is relatively low. Fertiliser may be used to increase fertility and thus fish production.
Semi-intensive fish farming requires a moderate level of inputs and fish production is increased by the use of fertiliser and/or supplementary feeding. This means higher labour and feed costs, but higher fish yields usually more than compensate for this.
Intensive fish farming involves a high level of inputs and stocking the ponds with as many fish as possible. The fish are fed supplementary feed, while natural food production plays a minor role. In this system, difficult management problems can arise caused by high fish stocking
densities (increased susceptibility to diseases and dissolved oxygen shortage). The high production costs force one to fetch a high market price in order to make the fish farm economically feasible.
The majority of freshwater fish are raised in ponds. Water taken from a lake, river, well or other natural source is channelled into the pond.
The water either passes through the pond once and then it is discharged, or it may be partially replaced so that a certain percentage of the total water in a system is retained. Pond systems that yield the highest fish production only replace water lost through evaporation and seepage. Water flow generally reduces the production of pond systems in the tropics.
Fish farming ponds range in size from a few dozen square metres to several hectares (ha). Small ponds are normally used for spawning and baby fish production, while larger ponds are used for the grow-out period. Production ponds larger than 10 ha become difficult to manage and are not very popular with most producers. The ponds illustrated here serve only as examples. The kind of pond a farmer will build depends very much on local resources, equipment and conditions.
Ponds are usually located on land with a gentle slope. They are rectangular or square-shaped, have well-finished dikes and do not collect run-off water from the surrounding watershed (see figure 17). It is important that sufficient water is available to fill all the ponds within a reasonable period of time and to maintain the same pond water level.
You should also be able to drain the pond completely when the fish are to be harvested. Side slopes should be 2:1 or 3:1 (each metre of height needs 2 or 3 metres of horizontal distance), which allows easy access to the pond and reduces the risk of erosion problems.
To prevent fish theft, try to locate the pond as close to your home as possible. Another method to keep thieves away from your fish pond is to place bamboo poles or branches in the water, which makes netting and rod-and-line fishing impossible. Apart from theft prevention, the poles and branches provide the fish with extra natural food.
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