Grow-out of milkfish in net-walled marine pens in La Union

Abstract

Grow-out of milkfish in 125 m² net-walled marine pens was tested in Santo Tomas Cove, La Union at three stocking densities of 6, 9, and 12 fish/m² and using commercial feed (crumbles and pellets) with 25–30% crude protein. After 115 days, survival of milkfish in marine pens was 92–97%. Fish stocked at 12/m² or 1,500/pen grew to average weights of 286 g, larger than the fish stocked at lower densities. Feed conversion ratio was 2.3 at the highest density and worse at the lower densities. Costs and returns of milkfish grow-out in marine pens at three densities showed that feeds were the most costly component (55–69%) of production. The milkfish harvest was equivalent to about 33 mt/ha at the stocking of 120,000 fish/ha. Only at this high density was adequate profit made for a 48% return on investment per crop. Two crops are possible in the Ilocos region during the dry season from November to June. Grow-out of milkfish in marine pens can be improved if seed and feeds could be procured at lower cost.