Intensive cage

It is unclear how many fish cages are operated to farm milkfish in the Philippines, but the culture of milkfish in cages at sea is booming. While at the moment its relative share to the total export production is around 30%, it is expected to increase in the coming years. This can be attributed to variety of reasons, one of which is that for cage farming at sea plenty suitable locations are available, in contradiction to pond and pen farming. Also, milkfish cultured in floating cages in a marine environment have better taste, making them very suitable for the export market, and fetch higher prices.

Key features
Average stocking density

20 – 50 fry/m2

Average productivity

20 – 40 kg/m2/year

# of crops per year

3

# of days per crop

120

Harvesting season

All year round

Type of farmer

Small-scale farms and corporate farms

Potential risks
  • A potential risk could be the pollution of marine waters

Type of farmers

Most farmers operate one or two cages as a family business and these farmers tend to be not very well organized. Export oriented businesses operate large amounts of cages, ranging from 10 to a hundred.

Production and harvesting system

Farmers use a monoculture system for the production milkfish in cages. The cages are placed in the sea where there is continuous water exchange. Square cages are typically 5 by 5 meter or 6 by 6 meter. Additionally round cages are available with a diameter varying from 6 to 20 meter.

Average grow out takes around 120 days to reach 250 to 300 gram and 180 days to reach 500 gram. In all provinces milkfish are harvested year round. Most farms harvest their milkfish at 250 to 300 grams, only a small number of farms specializes in larger sizes. The fish are typically harvested all at once by lifting the net of the cage. Survival rates are between 80 – 90%.

Stocking densities and productivity

In all provinces milkfish are stocked year round with the exception of the first few weeks of the rainy season. On average 20 to 50 fingerlings per m2 but this is highly dependent on the flow rate of the water and the depth of the cage.  Additionally, planned harvesting size also influences stocking density; if one wants to grower bigger fish for a longer culture period the stocking density must be reduced. Some farms stock fry directly while others first grow the fish in smaller nursery ponds also resulting in different stocking densities.

Average productivity ranges from 20 to 40 kg per m2. 

Use of seed, feed and other inputs

Fry and fingerlings originate from hatcheries based in the Philippines and Indonesia. Most farmers use smaller ponds (2,000 m2) where the fish are nursed for a period of 30 – 45 days. Almost all operators of marine cages use commercial pellet feeds due to the lack of natural feeds that exist in marine water. In cages the FCR is between 1:1.9 and 1:2.5. No chemicals are used in intensive cage systems.

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