Cage Culture of Silver Pompano

Aquaculture’s role in the Philippine fisheries industry has dramatically increased in the recent years. In 2007, 47% of the overall fish supply was contributed by aquaculture alone (BAS Regional Production Data, 2007).

With regards to cultured species, the paradigm shift from the promotion of traditional species to high-value species is gaining momentum with considerable impact on the domestic and international fish trade. Advances in aquaculture technology will make many high-value species available for culture and it is seen that these species will dominate the trade in the years to come.

On the other hand, the concept of seacage farming or mariculture is becoming popular among researchers, investors, stakeholders and commercial producers due to the decline of wild fish stocks. Most of the species being reared in this culture system are marine high-value species such as the silver pompano, Trachinotus blochii, Lacepede, a very promising food fish which has received considerable attention due to the following:

  •   its ability to readily adapt in the culture environment;
  •   acceptance of formulated feeds; and
  •   rapid and uniform growth rates compared to other farmed fish.

Geographic Distribution

Indo-Pacific: Red Sea and East Africa, to the Marshall Island and Samoa, north and southern Japan, south to Australia Habitat Juveniles inhabit sandy shorelines and shallow sandy or muddy bays near river mouths, while adults move out in schools to clear seaward reefs. Found near coral and rock reefs.

Food Habit

Feed primarily on sand mollusks and other hard-shelled invertebrates.

Description of the Cultured Species

The Trachinotus blochii has several common names such as Asian Pompano, Silver Pompano, Snub-nosed Pompano, Pompano, Buck-nosed Trevally, Dart Golden O, Golden Permit, Ladyfish, Long Dorsal Fin Pompano, Moonfish, Ovate Pompano, Palometa, Permit, Pompio, Round Pompano, Snub-nosed Dart, Snub-nose Swallowtail, Spinous Dory, Tropical Permit, Tropical Pompano (source: www.zipcodezoo.com).

Silver pompano belongs to the Carangidae family (trevally and jacks) and can be considered as selective grazer – feeding primarily along the bottom. Large and well-developed pharyngeal plates indicate an eventual adult specialization to feed on hardshell organisms such as clams or crabs.

The stomach of the pompano is well-defined and sac shaped, indicating omnivorous food habits. The characteristics of silver pompano exhibit a strong schooling behavior and high tolerance to a wide range of salinity. It takes three to four years for the fish to mature as broodstock.

Source of Stocks

At present, the supply of pompano fingerlings for grow-out in cage/pond comes mainly from hatcheries. Size of the fingerlings ranges from 0.5 inch to 1.5 inches depending on the availability.

Site Selection

Floating net cages should be installed in calm waters particularly in protected areas such as coves, sheltered lagoons, and bays. This would avoid damage to the structures during strong winds and waves.

  • The site should be free from pollution (industrial, agricultural, river and stream run-off) and as much as possible, protected from natural calamity such as floods, typhoons and others.
  • The site must be easily accessible, secured and must be within the fish cage belt or mariculture zone designated by the Local Government Units.
  • The site must also have good water exchange to maintain good water quality.

Cage Structure

The ideal size of cage for the culture of finfishes, particularly silver pompano is 4m x 4m x 3m. It is more manageable and modular farming system can be applied. Larger sized cages could also be used depending on the site, materials, and  management/ financial capability of the farmer/ investor.

The cage frame should be made up of High Density Polyethelene (HDPE) pipes as much as possible. Although expensive, it is resistant to big waves and strong currents. Other materials like galvanized iron (GI), wood or bamboo could also be used for calmer water area. The cost of bamboo is much lesser than the wood. However, bamboo poles have to be replaced once a year to ensure the safety of the stocks. Construction should also be durable enough to withstand strong wind and wave action.

HDPE pipes are buoyant and can serve as floaters of the cage. For the materials stated above, floaters are needed such as plastic drums, styrofoam, etc to provide buoyancy to the raft and also to the net cages.

The mooring system is made of concrete blocks or plastic drums filled with cement which are used as sinkers placed at the bottom in the four corners of the cage. It should be strong enough to hold and maintain the floating cage structure to withstand from all types of weather condition.

Net Cages

  • Nursery Net – B-net
  • Grow-out Nets – P.E.Knotted Net,  Super G No. 14 (mesh size 40cm)

Culture Techniques

A. Nursery Phase – Nursing or conditioning from fingerlings to juvenile stage.

  • Nursing or conditioning is necessary when fingerling size ranges from 0.5 to 1.0 inch.
  • Proper acclimatization of fingerlings prior to stocking should be done to achieve higher survival rate. This can be done in floating cages or hapa nets (4m x 4m x 3m) installed a week before stocking.
  • The nursing phase is also the period of weaning or training the fingerlings to feed on commercial feeds (fry mash).
  •  Stocking density ranges from 30-50 pcs/m3.
  • The stocks are fed with fry mash three to four times a day at 10- 20% body weight.
  • Culture period from fingerling to juvenile stage is more or less one month. This should be done with proper feeding management and daily monitoring of stocks.

B. Grow-out Phase

  • • The grow-out phase involves the rearing of fish from juvenile (12.0g to 15.65g) to marketable size (250g to 1.0 kg average body weight).
  • The net cages are made of knotless black nets (Super G No.14) installed outside the hapa net a week prior to stocking.
  • The stocking rate of silver pompano is 30 pcs m-3. Stocking is done early in the morning by hauling the bottom of the hapa net to the surface and transferring the juveniles by scooping to the grow-out nets. The hapa nets are removed.
  • Juveniles are individually counted before releasing to the main net.
  • After three months culture, the nets are replaced with bigger sized mesh nets (40cm) to ensure good water exchange and to avoid attachment of potential harmful metabolites.
  • Monthly replacement of nets is recommended.
  • Feeds and Feeding Rate – the stocks are fed with commercial pellets.

Feeding Rate:  Month -Feeding Rate (%BW) – Frequency

  • 1st – 10 – 3x daily
  • 2nd – 8 – 3x daily
  • 3rd – 6 – 3x daily
  • 4th – 4 – 3x daily
  • 5th – 4 – 3x daily

Sampling of Stocks:

  • Monthly sampling is done to determine the growth of stocks and to adjust the feeding ration.
  • Monitor water parameters regularly. The following are the optimum range for pompano:  (Values are taken from the research of Chavez et al., 2008 )
    • Salinity – 30-35 ppt
    • Temperature – 27-30°C
    • Dissolved Oxygen – 6.0 – 7.6mg/L
    • Water depth – 5.0m – 7.5m
  • The period of rearing ranges from four to seven months depending on the fish size requirement (pcs/ kg) in the market.
  • If properly managed and monitored, an initial stocking size of 12.0g to 15.65g) can be grown to produce the following desired size: Culture Period – Size Range
    • 4 months – 3-4
    • 5 months – 2-3
    • 6-7 months – 1-2

Harvesting

The stocks are ready to harvest after four to five months culture or as soon as the stocks reach the size of 250g per piece or more. Harvesting is done by hauling the bottom of the cage net to the surface and by scooping the stocks.

Random sampling is done and all stocks are counted individually to determine the rate of survival.

Post Harvest

Live marketable size silver pompano commands a high price in the domestic market. Hence the fish must always be kept in good condition.

Transport of live silver pompano is done in waterless, fiber glass tank or drums with aeration and oxygenated plastic bags packed in styrofoam boxes.

Water temperature is adjusted by gradually adding packed ice to lower the temperature to about 18°C-20°C.
Crushed ice are also placed on top of the plastic bags, tank or drums to maintain the coolness of water during transport.

Cost and Return of Seacage Farming (288 m3) of Silver Pompano (2 croppings)

For more information, please contact:

BFAR Region 4A – RFRDC
Freshwater Fisheries Research Station
Bambang, Los Baños, Laguna
Tel.: (049)827-3612 Fax: (049)536-8206

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