Technologies- La Niña

(Fisheries Sector)

Small farm reservoirs (SFRs) and small water impounding projects (SWIP) are used not only for irrigation, but also for fish production. With the heavy rainfall during La Niña, the size and depth of water impoundments can increase significantly, making these suitable for culture-based fisheries. Productive fishery is maintained by the optimum stocking in floating net cages of desirable fish species such as tilapia and carps that can thrive on natural food. Harvesting is done after five months of culture or when the residual water in the SFR/SWIP becomes inadequate to support fish production. The list of materials for a proposed fish cage is in page 242.

A floating net cage consists of the following structures:

a. Framework from which the net enclosure is attached and suspended. Bamboo poles serve as ideal material for the floating framework, serving as a catwalk and as a flotation system together with sealed plastic containers for increased buoyancy.

 

b. Net enclosure

A 5 m x 10 m x 2 m polyethylene net with mesh size # 14 is recommended.

c. Anchor or the mooring device made from wooden pegs/stakes, concrete blocks, or sand bags to keep the cage structure in position.

Requirements for Adoption

a. Minimum

• minimum SFR/SWIP area – 3 ha

• minimum effective water depth – 3 m

• minimum duration of effective water depth – 4 months

b. Support System

• hatchery facilities/source of quality tilapia fingerlings

• supplemental feed to support semi-intensive cage culture

• credit facilities to finance the capital investment for the cage culture project

• minimum capital investment of P20,000/cage

• LBP and QUEDANCOR can be tapped to provide soft loans for tilapia cage culture.

• training and extension services to provide the farmer with the basic information on cage management and operation

Advantages

• can adjust to the fluctuation of water depth and volume in the SWIP and SFR

• can sustain semi-intensive fish production

• maximizes the use of available water resources

• reduces risk of stock loss/escape during floods/heavy rains

• ease in securing/harvesting the stocks

• optimum recycling of farm inputs and wastes

• Wastes from the cages serve as fertilizer for the SFR/SWIP which in turn provide nutrient-rich water for crops.

Limitations

• vulnerability of cage structure to destruction during severe cases of flooding and very strong typhoons

• increase risk of theft and poaching

• higher capital investment

• require additional labor inputs

Recommendations

• Cage Design/Arrangement

- Construct square or rectangular cages to provide uniform water flow across the entire width of the cage.

- Install cages in a linear arrangement to facilitate efficient water exchange and create less resistance to wind and wave action.

• Culture Management

- Use Nile tilapia fingerlings (Oreochromis niloticus) for culture approximately 1 g in weight.

- Maintain stocking density of 10 fingerling/m3.

- Stock in early morning and during the cool part of the day.

- Give supplemental feeds (commercial feed pellet) at 5% of the total biomass preferably in two rations (morning/afternoon). Adjust the amount of feeds monthly.

- Provide feeds with 29% crude protein content.

This may be prepared by mixing 59 kg rice bran and 41 kg of fish meal to prepare 100 kg of feeds. Wheat flour, cowpea, or cassava can be used as binder.

- Promote the technology through information dissemination and technology-demonstration.

Possible Areas of Application

• Practically in any inland area with SWIP/SFR, but more particularly in CAR,
  Regions 3, 4, 10, and 12.

Dysfunctional Consequences

• Profitable cage operation may give way to the expansion of cages in small natural lakes with indigenous/endemic fishes.

• The farmer, out of convenience, may attempt to continue cage operation even during months when water may start to recede and could not maintain an effective water depth suitable for cage culture.

Sources of Technology

• Aquaculture Division and Technology Centers of the Bureau of Fisheries and Aquatic Resources (BFAR), 860 Quezon Ave., Quezon City;

• Technology and Livelihood Resource Center (TLRC), Gil Puyat Avenue , Makati City;

• Philippine Council for Aquatic and Marine Research and Development (PCAMRD), Los Banos, Laguna

List of materials for the proposed floating fish cage (5 m x 10 m x 10 m²).

  References

Costa-Pierce B.A. Small water bodies for sustainable fisheries production. ICLARM, Pub. 1991. p. 3-5.

Equia, R.V.; Equia, Ma. R.R; Basiao, Z.V. Simpleng gabay sa pagtitilapia: Pagpapalaki ng tilapia, 1996. - (Aquaculture Extension Manual No. 22).

Masatsune, Nomura, Tomyoshi. Fishing techniques. Japan International Cooperating Agency (JICA), 1975.

M N R. The culture of tilapia, 1982. - (MNR Instructional Manual No.1).

Roquel M.M. Socio-economic evaluation and policy analysis of the national program on small farm reservoir in the Philippines: A preliminary report, 1993.

SWIP’S/DDs. Ongoing projects. National listing of small water impounding projects, 1999.

Villacorta, L.G; Dureza, L.A. (eds.). Tilapia farming: Genetic improvement and advances on culture technology. In: Proceedings of the Third National Symposium and Workshop on Tilapia Farming, 25-27 November 1993. University of the Philippines Visayas, Iloilo City, 1994.

Yanmar Diesel Engine Co. Ltd. Yanmar Marine Engine Handbook.