The 782 ha brackishwater milkfish ponds of Jepara are operated by 448 fish farmers, or a holding of roughly 1.7 ha per farmer. It is not uncommon to see small areas of less than 1.0 ha being run by an operator, or such small areas being sub-leased to a third party.
While such ponds should, by reason of their limited extent be almost completely developed by now to such a degree that they could yield very high production, this, unfortunately is not true.
The ponds are single units, mainly for producing marketable milkfish, with a temporary “baby box” for the nursery, sluice for taking in water and drainage purposes. It is quite usual to see water only in the peripheral ditches and in longitudinal canals purposely excavated to hold the fish during the neap tide cycle. Maintenance of adequate water depth during the whole crop season is almost impossible. It appears as if this is not recognized as a major problem, that this situation is normally desired.
Main reasons for the intermittent exposure of the pond beds are (1) high elevation of the pond bottoms, (2) faulty sluices and (3) leaking dikes. The tidal condition has further aggravated the problem, in that water uptake can be limited. It is not surprising therefore that the small areas, with constant leaks through the dikes and sluices are quite often dry in the centre.
Under these conditions it is doubtful if the Government's efforts to raise production to a base level of 800 kg/ha/year, even if fertilizers and technical know how are made available, will succeed. Thus, the first consideration before improved techniques could be employed will be on proper development of the ponds. This will include (1) deepening and levelling to enable them to contain at least 20 cm of water at all times, yet be easily drained and substantially dried for periods not less than 2 weeks, and (2) putting up a workable layout to include provisions for better rearing of fry and fingerlings, easier water management, and ease in harvesting.
This is a very tedious, time consuming and expensive job. Care should be taken to leave as much of the top layer of the pond bottom to preserve some of the pond's fertility, otherwise enrichment of the soil if all of the top layers are removed will become a problem.
This nevertheless can be solved by “stripping”, i.e. digging alternate, parallel strips to pre-computed depths, leaving sufficient areas in between so that soils could be distributed and used to fill the excavated portions to the desired level.
7.2.1.1 Economical Tools Adaptable for Jepara Fishpond Improvement
The following labour saving devices introduced by the expert at the Centre might be of interest to local fish farmers who would like to undertake this work.
(1) Metal Digging Blades: - An improvement over the local “chankol” are two types of iron digging blades. The Malabon and Ilongo types, so named after the places in the Philippines where they originated, are best suited for fishpond work, the former for old areas where mangrove roots are no longer present, the latter for newly opened swamplands.
The Melabon type is a flat black iron plate, from 3 to 5 mm thick, with a blade about 20 cm wide at one end and tapering to and fitted with a wooden cross handle at the other. The length of the blade is 40 to 50 cm.
The Ilongo type is a long slender blade made of steel. Old spring leaves of tractors, big trucks, locomotive engine cabs, etc. are used to make them. It is about 12–15 cm wide at the cutting end, tapering almost to a sharp point at the other, to which a longitudinal wooden handle is fixed. The length of the blade is from 60 to 80 cm. The broad end as well as the sides are sharpened. It can slice through roots 5 cm in diameter or even more. Its sharp sides are sometimes used like a machete to cut at small shrubs and branches.
The technique of cutting out soil blocks for dike construction purposes is simple and easily learned. These blades are used also for digging puddle trenches, deepening of canals, repair of leaks and also for prying out jammed flushboards.
(2) Wooden Flatbeats: - Peripheral ditches are typical of Jepara fishponds and so are man-made islands. The ditches are the original areas from where soil for dike construction was taken. To provide canals where fish can seek refuge when pond waters are very low, strips parallel to one dike and extending from a peripheral canal to the other at the opposite end are dug. Instead of carrying it about, the excavated soil is thrown beside the trenches, forming islands. These high areas are utilized to some extent by planting them with agricultural crops. Nevertheless, the productive pond area is considerably much reduced. Other than carrying the soil in baskets, no cheaper method is used in transporting soil over far distances.
As an economical tool for this purpose, two wooden flatboats were introduced by Expert in the Centre's ponds. These boats, 4.2 m × 1.2 m × 0.3 m are flat bottomed with the top also as a flat deck. Completely sealed, they can carry almost one ton of load. Their shallow draft makes them ideal for work where water is only 30 cm deep.
(3) Slide Boards: - These are long flat wooden boards at least 25 cm wide and 2.5 cm thick. One side is planed to give a smooth surface. On both edges, a narrow strip of wood is nailed to form guard rails. The slide boards are set where soil has to be transported up to five m or further from the excavation site. The one end, at the excavation site, is raised, thus forming an inclined plane. At least two labourers are needed, one to do the excavation work, the other to receive the soil blocks at the other end. Water is splashed occasionally over the boards to make them slippery.
Soil may be transported to an even greater distance by setting a series of boards end to end and employing additional men to push the blocks until they reach the lower tip.
The digging blades, wooden flatboats and slide boards go hand in hand in excavation and levelling work. Pond workers of the Centre have been persuaded to make use of these simple devices. Since their usefulness has been demonstrated, participants who come to the Centre for training have been familiarized with their use and advantages.
All the excavated soil may not have to be brought to the perimetre dikes. Some could be used for constructing partition dikes for the various ponds and canal system needed for an efficient layout for rearing milkfish from fry to marketable size. Such additional improvements considered necessary are indicated below.
7.2.2.1 The Nursery System
This is composed of the nursery pond and the fingerling pond, with a catching pond separate or common for both. The nursery pond is the most elevated pond in the entire setup. Its size depends upon the number of fingerlings required by the production pond, extra provisions for mortality up to the time the fingerlings are stocked added, and its capacity to hold and grow fry to early fingerling size. The normal stocking rate is about 30 fry per m2, more if it is properly prepared and fertilized.
The fingerling pond is much larger and lower than the nursery pond. Here, early fingerlings from the nursery pond will be grown to medium or post fingerling sizes. The normal stocking rate for fingerlings is from 10 000 ha to 20 000 ha for a 30 day period. As a holding pond, it could accomodate, while waiting for better prices, marketable milkfish at from 0.5 to 1.0 kg per m3 of water.
7.2.2.2 Catching Pond
This is the deepest compartment, an accessory to the production pond for easy harvesting of marketable fish It is constructed in front of the main sluice. It should hold at least 40 m3 for each hectare of production pond. It is here where the fish are drawn by simple water management, taking advantage of the instance of the fish to go against the current.
Fish harvested from the catching pond are cleaner. Carefully taken out while still alive and killed in iced water in a portable pool or tank very little scales are loosened, the guts are clean and the freshness retained very much longer.
7.2.2.3 Supply Canal
This is provided to effect independent water management of the different ponds in the layout. In some cases, it is also used as catchment area for fish in lieu of the catching pond.
7.2.2.4 Sluices
All ponds and canal system are provided with appropriate sluices. The openings are of varied dimensions, sufficient to fulfil the water requirement of the ponds they service. They are classified as main, secondary and tertiary sluices. The main sluice supplies the needs of the entire pond, the secondary sluice that of the production and fingerling pond, and the tertiary sluice, that of the nursery pond. For Jepara conditions, Kalimantan wood, properly painted with one or two coats of coal tar may be used for the sluices. Wooden gates thus painted should last, properly maintained, for at least five years.
Suggestions for operation and management of a pond system, improved and developed as recommended above, are indicated in Appendix 1.
Expenses for development and improvement will be very high in view of rapidly rising prices and costs of commodities and services. Development time should also be as quick as possible. The fish farmers may have to rely on outside sources for financial assistance. Bank Rakyat Indonesia gives out capital investment and operational expense loans if collaterals are available. For fish farmers without any collateral the Government may have to formulate policies for granting such loans and make them available on easy repayment plans.
The fish farmer should also be included in programmes where he can avail himself of the needed supplies and materials at government prices. As of 1975, fishponds have been excluded from the BIMAS and INMAS agricultural improvement schemes. Chemical fertilizers were out of his reach. It is encouraging to know that the Government plans to make these items available to fish farmers very soon.
Experienced, technically trained men should be on hand to attend to the farmer's technical and marketing problems. There are at present only a few who could provide this service. There is need for expertise on cooperatives and a well organized outlet system for taking care of his produce, from icing, packing and transporting to selling in end markets of bigger centres of population where there is more demand and consequently better price for this fish.
For areas with small holdings per farmer, it will be well to set up a commercial nursery unit that can produce fingerlings in sufficient quantities to enable him to make at least three croppings per year. It may be privately run, with government technical assistance provided, or the Government might instal its own milkfish fingerlings nurseries in strategic areas where the best interest of the farmers could be served.
Main canals should be widened and/or deepened at regular intervals to ensure enough tidal flow and satisfy the water management programme for the individual ponds along them. The narrow tidal range already creates a problem of water intake and drainage. Siltation and constriction of water passages further aggravate the situation, making shallow ponds which otherwise could be easily dewatered entirely difficult to drain.
Most important perhaps is the profit incentive. Between 1974 and 1975, cost of inputs, operation, service and living have risen. Prices of some supplies and materials used in raising milkfish and the wholesale price of marketable milkfish itself are compared below.
| Items | 1974 | 1975 | Increase (%) |
| Fry, each | Rp 2.5 | Rp 5.0 | 100 |
| Rice bran, per kg | 12.5 | 27.0 | 116 |
| Cow dung, per kg | 1.0 | 2.0 | 100 |
| Milkfish, marketable, per kg | 250.0 | 275.0 | 10 |
At this stage, government assistance will be needed to enable the fish farmers to venture on this bold programme. Without it the pond operators in areas with small holdings, already operating at subsistence level, may not be able to organize themselves into an effective group that can give the leverage needed to get these facilities and assure them better profits.
