Effect of starvation on the initiation of feeding, growth and survival rate of juvenile seahorses, Hippocampus trimaculatus Leach and Hippocampus kuda Bleeker

In the investigation, the effect of starvation on the feeding ability, growth and survival rate of juvenile seahorses of Hippocampus trimaculatus Leach and Hippocampus kuda Bleeker during their early development was investigated. Newborn seahorses of H. trimaculatus and H. kuda could feed on prey and showed a great tolerance for starvation at temperatures of 23–25 and salinities of 32–33 ppt. When kept on starvation regimes of 0, 24, 48, 72 and 96 h, the first feeding rate (the proportion of juveniles within a sample with food in the gut) of juveniles of H. trimaculatus was 60%, 80%, 60%, 20% and 10%, respectively, and the first feeding intensity (the number of copepods consumed per juvenile per 60 min) was 5.3, 31.4, 7.6, 0.7 and 0.7 copepods per juvenile per hour, respectively. The first feeding rate of juveniles of H. kuda was 80%, 100%, 100%, 90%, 10% and 0, respectively, and the feeding intensity was 6.5, 20.2, 45.8, 14.5 and 0.7 copepods per juvenile per hour, respectively. Juveniles of H. trimaculatus reached the point-of-no-return (PNR) at 116.7 h postpartum and the PNR of juveniles of H. kuda was 115.6 h. The survival rate of the 24 h starvation group of H. trimaculatus was the highest, at 80.8 ± 2.9% (P < 0.05). When starved for more than 72 h, no H. trimaculatus juvenile could survive past 6 days. The survival rates of the 24 and 48 h starvation group of H. kuda were higher than that of controls at 7 days postpartum. However, when starving for more than 72 h, the longer the time of starvation, the lower the survival rates. The standard length of juveniles (H. kuda or H. trimaculatus) of starvation groups was significantly different from that of controls (P < 0.05). The relationship between the satiation amount and the age of juveniles of H. trimaculatus could be formulated: SA = 0.0284e0.2135D (R2 = 0.9567, P < 0.01).