赤点石斑鱼的胚胎和仔鱼形态发育

OBSERVATIONS ON THE DEVELOPMENT OF EGG AND LARVAE OF RED SPOTTED GROUPER

本文介绍了以人工繁殖所获的赤点石斑鱼受精卵为材料,进行孵化、培育的结果,连续观察了该种鱼的胚胎发育过程及其仔鱼的形态,并对其作了详细描述。

Fertilized eggs of red spotted grouper,Epinephelus akaara(Temminck ot Schlcgel)were obtained from induced spawning. The development of the eggs and larvae of thisfish were observed and studied in May, 1983 at Yan Tian mariculture ExperimentBasc, Nan Hai Fish. Res. Inst. The egg is pelagic (but the fertilized egg is demersal at the salinity below 27‰and pelagic abovre 29. 5‰), spherical in shape measuring 0 .74±0. 03 mm in diameter.The yolk is colorless, transparent, with a single oil globule, 0. 15±0. 01 mm in diame-ter. The egg develops to 2-cell stage 43 minutes after fertilization at the watertemperature 25. 0℃, salinity 30‰. The first egg hatches about 24 hours after fertiliza-tion at 25. 0--25. 9℃. No melanophores appeared in the periool of the embryonic deve-lopment. The newly hatched larvae measured 1.09--1 .21 mm in total legth. The number of myotomes is 11+14 =25. No pigment cells appeared in the body, but the surface ofthe body as well as the marginal fin and the yolk sac is covered with granules, and thefirst appearce of the melanophores was observed on the dorsal part of the alimentarycanal 15. 5 hours after hatching. The 3 days old larvae attained 2 .47--2. 62 mm in total length. The mouth opens,and the position of anus transfers to the middle part of the body and opens at situationof 10 th myotome, and it was measured 0. 125--1 .36 mm in mouth cleft length. Theyolk is almost obsorbed and oil globule was entirely consumed. In 4.5 days the larvae attained 2.49--2.70 mm in total length and yolk wasentirely obsorbed. In the stage of 6 days, total length of larvae was 2. 85--3. 17 mm.The dorsal fin base appeared just above the 1--8th myotome. The larval development of red spotted grouper is found to be similar in its earlylife history to those of other serranids, such as the brown spotted grouper(Epinephelustauvina Forskal) in Kuwait Waters, White-spotted green grouper (E. amblycephalusBleeker) and green grouper(E. awoara Temminck et Schlegel) in the East ChinaSea.