7 Harvesting Fish
Harvesting is the collection of fish from a pond for sale at market, or for cooking and preservation for family use. Harvesting can refer to collecting all the fish or to taking out only some of the fish (this happens often in tilapia ponds having both young and adult fish).
If the pond can be drained, harvest the fish by draining the pond into the catch basin and collecting the fish with a scoop net. If the pond cannot be drained, drain out as much water as possible and use a series of nets to catch the fish.
Types of Nets
There are different kinds of nets which can be used in ponds. Some nets, such as the one shown here are gill nets. Gill nets often have mesh sizes from 2-3cm; they are often used to harvest the largest fish in a pond and leave the smaller fish until they grow larger.
They are called gill nets because the fish pokes his head through the net mesh, and is caught around the gills as he tries to wiggle through the net.
Another net used to harvest fish is the seine. A seine can collect all the fish in the pond at one time because it has smaller openings (mesh size) than the gill nets, and it is usually made of heavier fibres to hold the fish. (See the end of this section for instructions on making a seine.)
Both seines and gill nets have lead sinkers (weights) attached to the bottom ropes. These weights hold the nets at the bottom of the pond (so the fish cannot escape underneath the nets as they are pulled). Seines and gill nets also have floats attached to the top ropes to help the net form an enclosure: the entire pond is netted with one sweep of the net.
Netting a Pond
Let out as much water as possible. NEVER LET THE WATER OUT COMPLETELY. As the fish have less and less water in which to live, they become excited and use up more oxygen when there is less available. Plan on harvesting while the water is draining out so the fish are caught before they are stressed. Or, drain the pond almost completely, and then let water slowly trickle through while netting the fish.
USING A SEINE
Place the net at one end of the pond and slowly draw the edges down the sides of the pond. Bring the middle of the net across the pond.
When near the other side, begin pulling the edges up onto the bank so that the net forms a u-shape in the pond. Pull up the bottom rope of the net along the pond bottom until it breaks the water surface. At this point the net is a bag shape and will hold the fish in (some seines already have a bag woven into them).
Pick the fish up one by one and transfer them to buckets or tubs of clear water for later weighing and transport.
OTHER HARVESTING METHODS
Fish also can be harvested by other methods. One method is to catch them with a hook and a line, but this method is time-consuming. In some parts of the world fish are harvested by dynamiting or poisoning the water. But these methods are dangerous and should never be done in a pond or any other waterway: dynamite and poisons can kill people and other animals, in addition to fish. NEVER HARVEST FISH BY DYNAMITING OR POISONING THE POND. There are easier and cheaper methods than these.
Marketing Harvested Fish
Once fish are harvested, they must be marketed. Marketing includes the transportation and sale of fish. As the introduction to the manual pointed out, one very important thing to consider before building a pond is the availability of a market. If a market is further away, the farmer must have transportation to it over passable roads. If the market is very near, he may want to advertise the date of his harvest by word-of-mouth so that the people will come directly to the pond to buy the fish. Also, he may want to make an agreement with a tradesman at the market so that he is sure he has a buyer for his fish when they are harvested. If there is no market, or if the farmer is going to use all the fish himself, then he probably will want to preserve some of the fish (see fish preservation).
Containers for storing live fish being taken to market.
Transporting fresh fish to market must be carefully done, so that the fish are not damaged. Usually, fish are handled in the same way they were handled when put into the pond. If it is not possible to get the fish to market right away, they must be preserved -- either on ice for quick sale in a nearby market; or salted, dried, smoked, or canned if going to a distant market. These methods are discussed in the next section.
Remember: Fish spoil very quickly in warm temperatures. Sell or preserve the fish right after harvesting.
After Harvest
After the pond is harvested, it should be prepared for the next stocking of fish:
* Plow the bottom of the pond
* Clear out predators, sticks, rocks, etc.
* Dry the pond bottom until the soil cracks
* Put lime on the pond bottom
* Wait two weeks
* Add water to the pond
* Check the water quality
* Put new fish into the pond
* Begin daily and monthly management of fish and ponds
* Breed
* Market
* Harvest
* Begin again
MAKING A SEINE
A seine can be made using materials found in the market. The materials needed are:
* rope
* cork floats
* lead sinkers (or-something heavy to help the net sink)
* netting
* sewing needle for nets
The directions for making the net are as follows:
* Tie a rope that will be used for the top and bottom lines between two trees. Use nylon rope, if possible, because it will last longer than cotton or hemp.
* Mark each rope at 15cm intervals. Make sure the rope is longer than the final net by a few meters.
* Stretch the netting until the meshes close completely; then count the number of meshes in a 23cm section. Good netting for a general seine will have 6 to 9 meshes in a 23cm stretched section.
* Use nylon string that is very strong. Wind a long section on a net needle. Then tie the end onto the lead line rope (top rope) at the first marking. Pass the needle through the number of meshes counted in the 23cm section of netting. Tie the string on the rope at the second marking.
* Repeat the process until the last marking on the top rope is reached.
* Pound the sinkers, or string them, onto the bottom rope at the 15cm intervals. Tie the cork floats onto the top rope at the same intervals.
* String the bottom line onto the netting in the same way as the top line.
REMEMBER:
The net must be washed, repaired, dried in the shade, folded, and put away in a cool, dry place after each use. A net which is taken care of in this way will last much longer.
