Publication: Advances in Polar Science (APS). Antarctic Research. Vol. 6, No. 1, 58~72, June 1995
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Author: Zhong Xuefeng and Wang Rong
CNARC member: Polar Research Institute of China (PRIC)
Abstract: Experiments and observations on reproduction of Antarctic krill, Euphausia superba Dana, were conducted on board ship of R/V "JIDI" during the austral summer of 1993 in the Prydz Bay region. The development of ovaria oocytes in gravid females, spawning episodes, and brood size were studied. The sexual maturity process and spawning season were discussed Fifty-three live gravid females captured at two stations in January, 1993 were cultured in a cool-room on board. They spawned within 1 to 16 days after capture. Most of them spawned only once except two, that spawned secondly on the 5th and 7th day after first spawning. The brood size of first spawning ranged from 225 to 5919 eggs with the average of 2132 eggs. The second brood was rather small, about 500 eggs. There were 0-213 (mean 32) mature oocytes remained in the post-spawn ovaries, and revitellogenesis was not observed. Brood size increased with the increasing of body length, but the correlation was not good. The number of ovarian oocytes in gravid females ranged from 2188 to 9263 with a mean of 5283. The composition of oocytes of different type varied in different samples. That all oocytes become completely matured seems to be an indication of pre-spawning. Spawning could take place through the summer with the peak-spawning occurring from late January to late February. Interannual variation in peak spawning season might be significant.
Keywords: reproduction, Antarctic krill, the Southern Ocean
