Apahap production in floating net cages
Efforts to raise the seabass or apahap are starting to bear fruit,
A study by Nestor D. Demenden, senior agriculturist of DA-Region 1, concentrated on culturing apahap.
The trial as conducted in Sto. Tomas, La Union. Water depth ranged from 1.5 to 2.5 meters during low and high tides, respectively.
Temperature and salinity ranged from 24.2 to 34.8 degrees centigrade and 32 to 36 percent respectively.
Bamboo was used to construct the platform where the net cages were suspended. Three bamboos (bayog) were arranged to form the raft-like structures needed to complete the platform. Four bamboo poles were arranged parallel with each other at two meters distances. They were fixed perpendicularly above it, forming six square holes for the net cages. Styrofoam floaters were fixed on the corners and inner joining of the platform. Anchors prevented it from drifting.
The net cages are square net walls (inverted mosquito netlike0 measuring 1.5 meters x 1.5 meters x 1.5 meters. A fine meashed net 9B net) was used for the juvenile cages where the fish was raised from two months.
The seabass were later transferred to the production cages, which was made of polyethylene net measuring 400/12 x k 12.
The fish were fed with cropped trash fish at 10 percent of biomass for the first two months. This was gradually reduced o seven percent on the third and fourth months, and five percent on the fifth month onwards. Feed was broadcast to the fish in the morning and afternoon daily.
Results showed that from an initial weight of 20.5 to 21.56 grams, the fish reached 282.3 to 302.4 grams in 180 days – or had a production of 10.73 kilograms per cubic meter mean net bodyweight gain. The project had an ROI of 67 percent from a food conversion ratio (FCR) of 6.93. The survival rate of the fish was 70 percent.
The trial also indicates that municipal waters can be used as both fishing ground and aquaculture area. – Wilhelmina Puyaban (Mariano Marcos State University)
Soruce: Greenfields, 1993