| 摘要: |
| 本文依据1989／1990和1990／1991两个南极夏季在普里兹湾以北海域所获的拖网样品，应用分布混合分析方法，研究大磷虾种群的年龄结构。结果表明，种群内最多可能包括6个年龄组：当年幼体，l+，2+，3+，4+和5+龄虾。年龄组成的地区变化较大，特别是1+龄虾，有时很强，有时完全不存在；5+龄虾的比重很小，平均不到1%，在多数样品中分析不出来。在全部6734尾所分析的大磷虾（当年幼体0+不包括在内）中，1+龄占25.63%，2+龄占22.53%，3+龄占43.46%，4+龄占7.89%，5+龄占0.49%。由于取样点都在外海，1+和2+龄虾的比例大大低于大磷虾种群实际应有的比例。在成体中3+龄虾占绝对优势（83.8％），反映生殖后的死亡率相当高。从各年龄组的平均体长可以发现，从未成体（1+）到次成体（2+）体长增长很快（14.22 mm/a），而从次成体到成体（3+），生长主要是性腺发育，体长增长缓慢（5 mm/a）。 |
| 关键词: 南极磷虾 年龄组成 普里兹湾 |
| DOI： |
| 分类号: |
| 基金项目:国家八五攻关专题，85－905－02－01号 |
|
| AGE-GROUPS OF ANTARCTIC KRILL (EUPHAUSIA SUPERBA DANA) BY DISTRIBUTION MIXTURE ANALYSIS FROM LENGTH-FREQUENCY DATA |
|
Wang Rong,Lu Beiwei,Li Chaolun,Wang Wenqi,Ji Peng
|
|
Institute of Oceanology, Academia Sinica, Qingdao 266071
|
| Abstract: |
| Age-groups of krill (Euphausia superb Dana) collected from the Prydz Bay region in austral summer of 1989/1990 and 1990/1991 were studied by means of distribution mixture analysis from length-frequency data. The results showed that krill population might consist of as many as six age-groups: 0+, 1+, 2+, 3+, 4+ and 5+. Differences in age structure of samples collected at different stations were great, especially in the strengths of 1+ age-groups. Age group 5+ was very weak (small), no more than 1% by average. Among the 6 734 specimens (larvae not included) analysed, 1+ accounted for 25.63%; 2+, 22.53%; 3+, 43.46%; 4+, 7.89% and 5+ 0.49%. The proportions of 1+ and 2+ age-groups observed might be much lower than the real ones in the krill population, since all the samples used for the present study were from the open area. That the 3+ was the dominant (87.3%) age-group among the adults indicated that mortality after spawning must be high. The increases between the mean body lengths of successive age groups showed that high growth rate (14 mm/a) occured in the stage from 1+ juvenile to the 2+ subadult, and decreased rapidly (5 mm/a) during the stage from subadult to the adult (3+), owing to the growth of sexual products. |
| Key words: Antarctic krill, Population structure, Prydz Bay |
