FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

To find the resolution of diet algae associated problems in abalone Haliotis diversicolor post-larvae rearing, four experiments were conducted using the post-larval abalone produced from different spawners: TT type (female and male all from Taitung), NN type (female and male all from Tainan), TN type (female from Taitung but male from Taitung) and HN type (female from Ho-ping Island, Keelung but male from Tainan). In experiment 1, the survival of TT post-larval abalone at the second day (2 days post hatch, 2 dph), cultured in Petri dish at 5 light intensities, was better in the blank (86 ~ 95%) than those fed with 3 diatoms on cover glass (24 ~ 86%). At 10 dph metamorphosis finished, higher survival (8 ~ 23%) was found in the blank at 10 ~ 75 μE, while 2 diatom groups survived (4 ~ 5%) only at 100 μE. In experiment 2, the survival of NN abalone post-larvae at the next day, cultured in Petri dish, was better (39 ± 9%) in the group addition with gamma-amino butyric acid (GABA) than the group without addition (24 ± 5%). The survival rates of abalone in the cultured periods after the 3rd day were better in the group, addition with GABA at 1st day then daily change of sea water with antibiotic and provided the diatom at 2nd day, than the group without both GABA and antibiotic addition. The best survival (8 ± 10%) at 20 dph was found in the group providing the Cocconeis placentula var. euglypta. In Experiment 3, the same 6 diatoms grew in Petri dish was washed to remove the floating algae, then the TN abalone post-larvae were put in and sea water with antibiotic changed daily, the significantly best survival (51.5 ± 7.3 %) at 20 dph and largest shell length (0.77 ± 0.14 mm) at 22 dph was found in the group fed with C. placentula var. euglypta. In Experiment 4, using the same rearing method, the better growth (0.53 ~ 0.57 mm) of the HN abalone post-larvae at 13 dph was in the groups fed with C. placentula var. euglypta, Nitzschia palea and Achnanthes submarina among 11 diatoms, but their survival (4.0~5.5%) was not significantly different. Reared in the 3-L tank with plastic plates and aeration, at 19 dph the abalone fed with C. placentula var. euglypta showed again the significantly best growth (0.96 ± 0.14 mm) but no different survival (16 ± 6%) among 6 diatoms. Reared in 250-L tanks with plates and aeration, at 20 dph the abalone on each plate (511 ± 215) and survival (2.15 %) was highest in the group fed with A. submarina, and the shell length was 1.08 ± 0.25 mm. In conclusion, two diatoms C. placentula var. euglypta and A. submarina showed the better survival and growth for post-larval abalone H. diversicolor.