1. Introduction
The seasonal tanks project, as outlined in this report, will depend on an adequate and timely supply of fingerlings, in particular of carp. While it is possible to collect fingerlings of milkfish and perhaps also of T. mossambica in the wild, this is not so for carps in Sri Lanka. They need to be spawned and reared in a hatchery. The effort needed to make carp fingerlings available constitutes a major cost of the proposed seasonal tanks programme.
In this annex the Mission first identifies the components of a carp hatchery designed to produce 1 million fingerlings per year. It then estimates the cost of operating such a hatchery. However, in order to conform with the scale of operations foreseen in the seasonal tanks programme, the costing is done for a carp hatchery capable of producing 5 million fingerlings per year.
2. Facilities
2.1 The facilities identified below should be sufficient to produce one million fingerlings in the period of one year:
| Spawners | ||
| Number of fingerlings to be provided | 1 million | |
At 50 percent survival from fry to fingerlings in 4–6 weeks time, the number of fry needed for the above | 2 million | |
At 50 percent survival from spawn to fry in 2–3 weeks, the number of spawn needed for the above | 4 million | |
At 80 percent hatching and survival up to spawn, the number of fertilized eggs needed for the above | 5 million | |
At 80 percent fertilization total number of laid eggs to yield the above number of developing eggs | 6.25 million | |
Average total weight of gravid female spawners needed to yield the above number of eggs: | ||
| Bighead carp at 100 000 eggs per kg body weight | 62.5 kg | |
| Grass carp at 50 000 eggs per kg body weight | 125.0 kg | |
| Catla at 80 000 eggs per kg body weight | 78.0 kg | |
| Rohu at 120 000 eggs per kg body weight | 52.0 kg | |
| Common carp at 60 000 eggs per kg body weight | 104.0 kg | |
| Average of the above five | 85 kg | |
At 50 percent success in hypophysation, weight of gravid female spawners required to yield 6.26 million eggs | 170 kg | |
Considering that only about 60 percent of the female spawner stock usually attain full maturity condition actual weight of female spawners required to be maintained | 284 kg | |
| Weight of oozing males required for 170 kg of female spawners | 340 kg | |
Considering that normally only 70 percent of the stock of adult males attain the freely oozing condition, total weight of male spawners to be maintained | 486 kg | |
Total weight of male and female spawners to be maintained in the farm, to be utilized for production of 1 million fingerlings as above | 780 kg | |
At 1 000 kg of spawner stock per ha, the area required for maintaining spawners needed to produce 1 million carp fingerlings | 0.78 ha preferably as four ponds each 0.2 ha |
2.2 Hatchery facilities for 6.25 million eggs
A 100 1 hatching jar with continuous filtered water supply from below, adjusted for complete renewal of water every 8–10 minutes, can successfully hatch 500 000 eggs in about 15–18 hours at 27–29°C water temperature.
If the hatchery has 5 such hatching jars, the required number of eggs could be hatched in three shifts in 3–4 days, as the required number of eggs become available.
The hatchlings will be held over for 2 more days in the hatchery, in cement tanks, with running water and aeration, until their yolk is absorbed, and they are ready for taking in food from outside.
2.3 Intensive rearing facilities to rear 4 million carp spawn to fry stage (15–20 mm) in 15–20 days
Cement tanks, each 20 m2 or more in surface area with 1.0 m or more depth of water, preferably with filtered pond water available for daily partial renewal and provided with extra aeration and a water filtration/aeration arrangement using airlift pumps could be used for intensive rearing of carp spawn.
Portable PVC pools, 10 to 20 m2 in surface area can also be used as rearing facility in any desired location.
At a stocking density of 10 000 spawn per m2 (depth 1 m), a 10 m2 tank can hold 100 000 spawn for rearing. Four hundred m2 of cement tank area would be required to rear 4 million spawn. If these are reared in two batches, half the above area would be adequate for the operation.
Aeration and water supply arrangements made for the hatchery will supply the rearing facility also.
The spawn will be fed partially on live feed and partially on compounded artificial feed.
For culture of live feed (zooplankton organisms, predominantly the water flea, Moina spp.), one earthen pond, 1 000 m2 in area, has to be set apart, besides 4 cement tanks, each 20 m2 or more in area.
Compounded artificial feed will be processed to suitable particle size depending on the size/age of fry to be reared.
2.4 Grow-out facilities to rear 2 million carp fry to fingerling size (7–10 cm) in 4–6 weeks
Grow-out facilities will be earthen rearing ponds, with supply and drainage arrangements, each pond 1 000 m2 in surface area or more.
These ponds will be prepared in advance by suitable aquatic manuring.
Two to three weeks old fry may be stocked in such ponds at a density of 1 million/ha.
Total rearing pond area required is, therefore, 20 ponds each 1 000 m2 in area (2 ha).
During the rearing period the fry will be artificially fed with compounded feed.
Water in the ponds will be partially renewed, depending on the growth of the fry and the water conditions prevailing in the ponds.
After the stock of fingerlings is removed from the rearing ponds, a limited number of selected, fast-growing fingerlings can be grown in these ponds to build up future spawner stock.
3. Cost of running a hatchery designed to produce 5 million fingerlings in a year
The type and size of facilities are discussed in the preceding section (2) of this annex. They are listed in tables 18.1 and 18.2.
It is proposed that plastic pools (with metal support) be used for intensive rearing of carp spawn. A pool with 15 tons capacity would be suitable. Each pool would be aerated using air blowers. Water will be filtered and purified using airlift pumps. Selected tanks will be stocked with carp spawn at the density of 10 to 20 per litre of water and reared to advanced fry stage (20 mm) in 15 days. They will then be released into earthen, grow out ponds.
The spawn will be fed partially on compounded formulae feed, prepared out of locally available raw materials, and partially on live zooplankton, especially mass cultured in cement tanks using organic and inorganic fertilizers.
Water supply arrangements to the ponds and the cement tanks will be from an overhead tank. At least two, and possibly three, crops of spawn are expected to be reared in these plastic pools in a season.
The cost of running the carp hatchery for a year is shown in table 18.3. The proposed personnel consist of: Manager, Deputy Manager, Fish Culturists (2), Extension Officers (4), Fish Farm Superintendent, Laboratory Assistant, Hatchery Assistant, Foreman (mechanic), Electrician, farm labourers (45), drivers (3), and watchmen (4).
Brood stock and fish in the fry to fingerling stage are fed with a feed composed of rice bran (75 percent), fish meal (5 percent), coconut ponac (10 percent) and wheat bran (10 percent). In late 1980, the ingredients, when mixed, would have cost about Cey.Rs. 1.26 per kg. Brood stock is given a ration equivalent to 2 percent of their body weight per day. The conversion ratio for the food given to fry has been assumed to be 4:5. In total, about 100 tons of feed will be required per year.
The basic transport charge used in the calculation is Cey.Rs. 5 per km and ton transported. The charge for transporting 18 000 fingerlings in 180 tins each holding 17 litres, over a distance of 100 km then comes to about Cey.Rs. 40 per 1 000 fingerlings. The cost of plastic bags and oxygen are minimal. It is assumed that the transport will be carried out in vehicles arranged for the occasion by the recipient of the fingerlings.
Table 18.3 ends with an all-inclusive cost (even transport of fingerlings is included) just below Cey.Rs. 3 million for a year. The cost per fingerling therefore equals about Cey.Rs. 0.60. Expenditure per fingerling is about Cey.Rs. 0.30; the rest are charges for depreciation and interest.
Fixed costs are high, 73 percent of total (personnel, interest and depreciation). Thus, it is absolutely essential to keep the carp hatchery producing at, or near, its designed capacity. If this is not done, the fingerlings will become prohibitively expensive.
Table 18.1
Investments required for a carp hatchery designed to produce 5 million fingerlings per year
| Item | Unit | Cey.Rs./unit | Number of units | Cey.Rs. (in '000) | Economic lifetime | |
| Approach road | km | 500 000 | 1 | 500 | 50 | |
| Ponds: | ||||||
| - | spawners (0.2 ha each) | ha | 400 000 | 4 | 1 600 | 50 |
| - | grow-out (0.1 ha each) | ha | 500 000 | 10 | 5 000 | 50 |
| - | “moina” culture (0.1 ha each) | ha | 500 000 | 0.5 | 250 | 50 |
| Pools for intensive rearing of spawn | each | 15 000 | 100 | 1 500 | 5 | |
| Buildings: | ||||||
| - | office, lab, store | m2 | 1 500 | 500 | 750 | 40 |
| - | hatchery | m2 | 1 500 | 330 | 495 | 40 |
| - | staff quarters (22) | m2 | 1 500 | 1 760 | 2 640 | 40 |
| Vehicles | each | 130 000 | 3 | 390 | 4 | |
| Equipment (see table 18.2) | 760 | 10 | ||||
| Miscellaneous | % | 10 | 1 200 | 10 | ||
| Total | 15 085 | |||||
Table 18.2
Cost of hatchery and rearing equipment
| Quantity | US$ | |
Power generator: 440 V 3 phase, 10 kW (standby source of power), electric starting | 1 | 4 000 |
In situ water filtration unit with self priming pump run by a 5 hp motor with starter and switch | 1 | 2 000 |
Air blowers, displacement 5 m3 or above per minute under 0.3 kg. Water pressure, with sound muffler, low rpm with corresponding hp motor | 7 000 | |
Hatching jars made of transparent fibreglass or perspex; with spout at top and muffler (shower like) at the bottom | 44 | 3 000 |
| Superior quality brass wheel valves 0.75", 1", 2" and 2.5" | As required | 1 500 |
PVC pipes 2.5", 2", 1.5" and 1" as required. Air tubing, valves, connections, etc. | As required | 2 000 |
Laboratory equipment, including one stereoscopic binocular and one research microscope, photomicrographic (p.m. - 10), one ph meter, bolting silk, nylon netting, thermometers, air conditioner for temperature controlled room | As required | 10 000 |
| Vehicle for transportation of spawners and fingerlings - insulated diesel truck | 1 | 12 000 |
Fingerlings transport facilities like 02 cylinders, plastic bag sealer, etc., plastic for making bags | As required | 3 000 |
| 44 500 |
Hatchery shed, spawneries, hatching jar supporting benches, etc., machinery room, office, laboratory, temperature controlled room, etc. are to be locally constructed. Plastic pools will be used for spawn rearing.
Table 18.3
Annual running costs for a carp hatchery designed to produce 5 million fingerlings per year
| Item | Unit | Cey.Rs./unit | Number of units | Cey.Rs. (in '000) | Percent | |
| Personnel | 67 | 563 | 21 | |||
| Feed | kg | 1.40 | 100 000 | 140 | 5 | |
| Electricity | KwH | 0.60 | 100 | |||
| Transport: | ||||||
| - | fingerlings | 1 000 | 40.00 | 5 000 | 200 | |
| - | other | ton/km | 5.00 | 6 000 | 30 | |
| Office material | 50 | |||||
| Laboratory material | 25 | |||||
| Miscellaneous | % | 10 | 110 | |||
| Sub-total | 1 218 | 45 | ||||
| Depreciation | 842 | 31 | ||||
| Interest | % | 10 | 663 | 24 | ||
| Total | 2 723 | 100 | ||||
