1Yaeyama Station, National Center for Stock Enhancement, Fisheries Research Agency, Ishigaki, Okinawa 907-0451, 2Kamiura Station, National Center for Stock Enhancement, Fisheries Research Agency, Kamiura, Oita 879-2602, 3Tamano Station, National Center for Stock Enhancement, Fisheries Research Agency, Tamano, Okayama 706-0002, Japan
This study investigated the effects of delayed initial feeding on the growth, feeding, and survival of early stage red spotted grouper Epinephelus akaara larvae in relation to the absorption of endogenous reserves at 26°C. Five different feeding regimes were prepared as follows: No. 1: rotifers fed initially at 0 hours after the onset of feeding (HAOF), No. 2: rotifers fed initially from 6 HAOF, No. 3: rotifers fed initially from 12 HAOF, No. 4: rotifers fed initially from 18 HAOF, and No. 5: starved control. The larvae were fed rotifers (a small Thai strain) at a density of 20 ind./mL except for No. 5. Feeding amounts and survival showed a tendency to be lower when the onset of feeding was delayed. Larval growth showed significant differences between No. 1 and No. 2-4 at 66 HAOF (p<0.05 or 0.01). In contrast, starved larvae (No. 5) showed negative growth from 12 to 66 HAOF. The beginning of the negative growth point coincided with the time of complete oil globule absorption. These results indicate that larval growth was closely related with endogenous reserves, and larvae possess a very short period during which they are resistant to food deprivation. We conclude that their growth and survival are affected if they fail to initially feed within 6 HAOF at 26°C.