Culture and economics of wild grouper (Epinephelus coioides) using three feed types in ponds

The performance of wild Epinephelus coioides juveniles was compared by feed ing with live tilapia juveniles, fish by-catch, and formulated diet for 5 m onths in grow-out ponds. To minimize cannibalism, the groupers were graded into small (BW=24.9 +/-7.3 g), medium (45.8 +/-5.7 g), and large (84.1 +/- 30.0 g) size groups as block in a Randomized Complete Block Design (RCBD) a nd reared in nine 350-m(2) ponds. To supply the tilapia juveniles, adult ti lapia were grown 2 months prior to stocking of grouper at a rate of 15 tila pia/grouper. Grouper fed by-catch were significantly higher (P<0.01) than t he other treatments in terms of final length and total production. The qual ity of by-catch could be gleaned by its efficient feed conversion ratio (FC R) of 1.0 (dry basis), significantly better (P<0.01) than the formulated di et that had an FCR of 2.8. Using by-catch, 47% of the harvest weighed >400 g and only 14% was classified <200 g. The cost of juvenile grouper and feed s represented 88-89% of the total investment in all treatments. Economic se nsitivity analysis showed that a combination of improvement in factors such as price of grouper juveniles, feeds, yield, survival, and FCR would resul t in higher return-on-investment (ROI). When cost and returns were consider ed, feeding juveniles with by-catch was more profitable because it resulted in net income of Php 361,623/ha/year, an ROI of 155%, and a payback period of 0.4 year. The results clearly show that these economic indicators appea r to be attractive, thus making grouper pond culture using by-catch a viabl e industry. More research efforts should, however, be directed towards deve loping a cost-effective formulated diet for the grow-out culture of E. coio ides. (C) 2001 Elsevier Science B.V. All rights reserved.