MORPHOLOGYCAL DEVELOPMENT AND GROWTH OF YELLOWFIN TUNA Thunnus albacares LARVAE FROM CAPTIVE BREEDING
This trial was designed to study morphological and larval development of Yellowfin tuna, Thunnus albacares to develop optimal larval rearing strategy. Trial was conducted in hatchery of Institute for Mariculture Research and Development (IMRAD), Gondol-Bali. Eggs was collected from broodstock reared in floating net cage. Mean diameter of eggs were 872 ± 18 µm and oil globule 207 ± 7 µm. Larval rearing tanks were fiberglass reinforce plastic (FRP) with volume of 6 m3. Mean notochord length of newly hatched larvae (D-0) was 2.56 ± 0.11 mm with diameter of oil globule of 0.20 ± 0.00 mm, transparent, eyes, mouth and digestive system were not developed yet. During the trial, 10 larvae were sampled randomly daily from D-1 to D-12, on D-15 and on D-20. Larvae were observed under binocular microscope equipped with digital camera and connected to computer with ACT-1 and WinRoof software for further image analysis.
The results showed that newly hatched larvae until D-2 had some pigmentation on the body (melanophore), eyes, mouth and digestive system developed further. At late D2, mouth and anus were opened and pigment disappeared. On D-3, yolk and oil globule were totally absorbed and larvae started to exogenous feeding by actively swimming to search for feed.
Teeth on lower and upper jaw were already appeared on D-7. Dorsal and pelvic fin started develop and notochord started to bend on D-12. Caudal fin started to change from rounded to fork-like shape on D-15 and metamorphose to juvenile started on D-20 with mean total length of 18.32 ± 0.78 mm and fork length of 15.55 ± 0.59 mm.