By Rafael D. Guerrero III
Calauan is a second-class municipality in the province of Laguna about 75 kilometers south of Manila.It has a population of more than 80,000 people and elevation of 65 meters above sea level. While it is known as “The Home of the Sweetest Pineapple in Laguna,” the town is also a major producer of Nile tilapia fry and fingerlings for culture in the floating cages of Taal Lake in Batangas, which produced over 22% of the total farmed tilapia production (261,210 metric tons) in the country in 2015.
We visited the tilapia hatcheries in Barangay San Isidro in Calauan recently to assess their setups. The hatcheries consist of earthen ponds that were developed from once irrigated rice fields. Water is mainly from an irrigation source. Ranging in size from 1 to
6 hectares per hatchery, the hatchery areas are leased by financiers from their owners
who may also be employed in the operations.
The tilapia breeding and nursery ponds in the Calauan hatcheries measure 300-600 m2 each or larger with water depths of 0.6-1 meter. Nile tilapia breeders (mature male and female fish) with body weights of 50-80 grams a piece (3-4 months old) are initially
stocked in the ponds at a density of 4-5/m2 and sex ratio of 5 females to a male. With feeding of commercial pellets, 500 of the breeders can produce 100,000 fry in a month during the good weather months of June to November. Fry released by the mouth-brooding female breeders are collected 2-4 times a day along the edges of the breeding ponds at about 10 days from stocking of the breeders for 2-3 weeks using fine-mesh dip nets.
After a month of breeding, the ponds are drained and the breeders are transferred to net cages in nearby ponds for conditioning (rest and recuperation) period of 3-7 days. The breeders are then restocked in the ponds for the next breeding cycle. The breeders are utilized by the hatcheries until they attain weights of more than 300 grams each in about 18 months when their productiveness declines.
Most of the 1-2-day old fry (from the time they are released by the females) produced in the Calauan hatcheries are bought by buyers who supply the nursery operators in Laurel, Batangas. Rearing of the fry to fingerling-sizes (more than 1 inch long) is done in nursery ponds for 5-6 weeks before being brought to the lake for further growth in floating nursery cages and stocking in the grow-out cages. The fry are sold at R4,000 per thousand (P0.04 each) in Calauan and transported in closed plastic bags with water and pressurized oxygen.
Some hatcheries in Calauan like the MGB Aquafarm treat the newly-collected fry for sex reversal by feeding a commercial male hormone-feed for three weeks in nursery ponds at a stocking density of 500/m2.The treatment enhances the growth of the fry and results in their being 95-99% males which makes them yield more in the grow-out cages because of the male’s growth advantage over that of the female in the species. After the sex reversal treatment period, the fingerlings are further reared to larger sizes in the ponds for another 2-3 weeks before being brought to Taal Lake for stocking in floating nursery and grow-out cages. Transport of the fingerlings from Laguna to Batangas is also done using oxygenated plastic bags with water. The sex-reversed fingerlings sell for P0.45-P0.50 each.
The major problems encountered by the tilapia hatchery operators in Calauan are mainly related to weather conditions. During the hot months (April-May), water temperature in the ponds (higher than 32OC) can cause mortalities particularly for the fry/fingerling due to heat stress. On the other hand, during the cool season (December to February) when water temperatures can be 24-26OC, fry production goes down by as much as 50% because of the reduced breeding capacity. Breeders tend to be inactive and take in less feed at lower water temperatures compared to their normal temperatures of 28-32OC.
The hatchery operators of Calauan also said that they need government assistance in the form of technical services (extension), improvement in the quality of tilapia breeders and financing with low interest rates for increasing their productivity and economic returns.
This appeared in Agriculture Monthly’s November 2018 issue.