Crispino A Saclauso
University of the Philippines Visayas
Title: Bottom Feeding and High Density Stocking Improve Yield and Profitability of Milkfish Culture in Marine Cages
Biography
Biography: Crispino A Saclauso
Abstract
High density stocking often results in slow growth and low survival in aquaculture. This is attributed to diminished space, inequitable access to food, and aggressive behavior as a consequence of crowding and deterioration of water quality at high population densities. Under crowded conditions, aggression depresses growth that results in the deaths of subordinate conspecifics. In non-aggressive species like milkfish, crowding significantly affects size variance hypothesized to have been caused by reduced food access in high density culture where fish are fed from the top.
The study aims to improve yield and profitability of milkfish production in high density culture through bottom feeding. With increased density, yield per unit volume is also expected to increase thus diminish the area required in generating equivalent production at lower stock densities.
Milkfish at densities of 50 pieces m-3, 75 pieces m-3 and 100 pieces m-3 were reared for 120 days in replicated 5mx5mx5m floating net cages in a marine cove with a depth of 10 m and a flow rate of 8 cm sec -1. Fish were fed floating pellets through top demand feeder and hydro-kinetic bottom feeder.
Bottom feeding increased production of milkfish cultured at very high density. Net yield (kg m-3) increased by 75% with the doubling of stocking density from 50 m-3 to 100 m-3. Size variance was reduced and condition index (K) and feed conversion ratio (FCR) were improved. Bottom feeding optimizes food utilization through equitable and better access to food hence, reduces feed wastage. Bottom feeding and high density stocking enhances production efficiency without compromising environmental integrity.