Abstract:

During the First Chinese Antarctic Expedition extensive IKMT (Isaacs- Kidd midwat-er trawl) tows were made. The body length, weight, sex and sexual maturity of Euphausia superba in the samples were determined. And the fecundity of 65 gravid females were measured. Among 3640 individuals, the sex of which can be determined, only 38.1% are males. Evidence shows that the larger the body length, the smaller the percehtagp of male is. In group of 51-55 mm body length the male decreases to 20.7%. In group larger than 55mm the male drops to 8.3%. This is probably due to die off of male after pairing or due to changes in behavior. The fecundity of gravid female ranges from 2457 to 10799. The relation between body weight (W) and fecundity (F) is as follows: F=4890×W-190(r=0.9178) The weight of ovary is about 42.14% (s.d. = 6.96%) of the body weight. The average body weight of spent female (3EF) is olny 65.6% of that of gravid female. The loss of weight after spawning is as big as 34.4%. There is a great variation in sexual maturity from place to place. In water north of South Shetland Islands only adults were found in swarms. Gravid female account for 20.2%, spent female 3.4%. In the eastern mouth of Bransfield Strait, owing to the influence of Weddell drift the sexual maturity is much lower than other parts observed. No gravid and spent female were found. The sub-adults were dominant in the swarms.