Aquaculture Crsp 22nd Annual Technical Report

Work under this investigation included farm survey, extension, and research components using both the CLSU research station and demonstration farms. An experiment was conducted for the determination of optimal stocking sizes, considering the growth and survival performance of various sizes of fingerlings along with economic factors. Size #22 sex-reversed nursery phase fingerlings of Nile tilapia (Oreochromis niloticus) of the Genomar Supreme Tilapia or GST strain were grown in 15 2 x 2 x 1m hapas in pond at a stocking density of 200 fish m-3 to attain size #10. After two weeks, another batch of size #22 sex-reversed fingerlings were grown in 15 nursery hapas at 200 fish m-3 to attain size #14. In the grow-out phase, 12 500m2 ponds were used in the study to determine the growth, yield, and survival of Nile tilapia (Oreochromis niloticus L.) in ponds. The treatments consisted of the following: I) direct stocking at size #22; II) stocking at size #14; and III) stocking at size #10. The various treatments and replicates were assigned randomly in the ponds following a completely randomized design. Treatment III gave the highest extrapolated fish yield (3,799 kgha-1), followed by Treatment II (3,065 kgha-1) then Treatment I (2,738 kgha-1). Analysis of variance on fish yield showed significant difference between Treatments I and III (P < 0.05). Specific growth rate likewise significantly differed among treatments (P < 0.01). Survival rate of Nile tilapia was also significantly affected by stocking size of fingerlings. Higher survival rate was obtained with larger size of fingerlings at stocking for grow-out production In addition, a farm survey was conducted, in which 70 participating farmers were queried on a range of practical issues. This has established a database of farm practices (see Appendix 1) which is being expanded upon by additional survey work, and which will be useful for a variety of applications.