Experimental Starvation of Acanthopagrus schlegelii Larvae, and Definition of the Point of No Return

Abstract:

The potential effects of starvation on the growth, feeding, and survival of Acanthopagrus schlegelii larvae were investigated at a water temperature of 18℃~19℃ by using ecological experimental methods. Along with the detection of the initial feeding rate and the point of no return (PNR), the optimum initial feeding time of the larvae were also ascertained. The results showed that larvae started feeding on the third day post hatching (dph), and the yolk sac and the oil globule disappeared at 4 DPH and 6 dph, respectively, which suggested that the duration of the mixotrophic stage was about 3 days and larvae were vulnerable to starvation. When the fish opened their mouths, the initial feeding rate was only 30%, which then rapidly increased to the highest level of 90% at 5 dph, after which it gradually declined to 45% at 7 dph, which denoted the PNR. Significant variation was found between the starved and control groups after 6 dph (P<0.05). Reduced mobility, distorted or deformed bodies, and increased mortality were observed in the starved larvae after the PNR. All the starved larvae died before 10 DPH. In brief, our study suggested that A. schlegelii larvae were vulnerable to starvation and the optimum initial feeding time of the larvae was within 4 days after their mouths opened.