A TEST OF AN ON-FARM SELECTION PROCEDURE FOR TILAPIA GROWTH IN INDONESIA

Modern intensive fish farming encourages the use of superior strains o f fish developed in centralized research institutions. In many artisan al fish farms these strains may not be available or suitable: environm ental conditions may differ from those optimal for the superior strain s, or the species of fish desired in particular farming systems may no t have been the subject of a selection programme. In such cases, the o ption would be for farmers to improve their own strains using procedur es that are within their financial and technical capabilities. One gen eration of mass selection for size-specific growth rate of tilapia was performed on a fish farm in West Java, Indonesia. Selection was appli ed in two steps over the 6 month grow out period following the initial stocking of size-graded fingerlings acquired from the farmer. Size gr ading, rather than age-matching, was a key step in simplifying the pro cedure for on-farm use. Selection and testing of the offspring were co nducted in hapa nets set up in farm ponds. The selection resulted in a significant positive response of 2.3% as measured by the percent diff erences of the lengths of the selected offspring from the control offs pring. A rough estimate of realized heritability amounted to 0.12.