| Popis: |
[Abstract]Successful spawning of yellowfin tuna, Thunnus albacares under land-based concrete tank facilities has been started almost two decades ago at the Achotines Laboratory of the Inter-American Tropical Tuna Commission (IATTC), Las Tablas, Los Santos, Panama. However, very little attempt has been made to study nutritional aspects of this valuable species. The quality of eggs and their offspring completely relies on quality of broodstock diet. ln addition, broodstock diet together with some environmental factors regulates the spawning performance, fecundity, hatching and larval performance. Two trials were conducted from May 22 -June 26 (Trial 1) and November 1 -December 13 (Tria12), 2011. Time to spawn, fertilized eggs, hatching rate and water parameters were collected on regular basis. Similarly, egg and oil globule diameter, length of newly hatched larvae (NHL) were measured and eggs and NHL were sampled for proximate analysis. The water quality parameters during the experimental period were fairly constant and may have no effect on spawning or hatching rate. The size of eggs was found very similar in both trials under the existing condition. The fecundity was found to have direct effect with the feed composition, and spawning was delayed by five minutes each day while the feed composition was in changing state in trial 1 (phase 1). The effect has c1early observed with low protein and lipid content in eggs and NHL in phase one. The results from this study indicated the delay of spawning might be due to low levels of lipid and protein transferred in eggs from diet. It seems that the prevailing environmental condition in Achotines laboratory is suitable for rearing broodstock; however, providing correct nutrition to the broodstock, the egg quality, spawning performance, hatching rate and larval performance could be improved in certain extent. |
