普里兹湾邻近海域大磷虾的种群结构研究

POPULATION STRUCTURE OF THE ANTARCTIC KRILL IN THE PRYDZ BAY REGION,INDIAN OCEAN SECTOR OF THE SOUTHERN OCEAN

本文依据 1 989/ 1 990和 1 990 / 1 991南极夏季在普里兹湾邻近海域所获取的拖网样品 ,对大磷虾 (Euphausia superba Dana)的种群结构进行了分析。体长频数分布表明 ,种群中主要包括4个年龄组 ,即 1 + 、2 + 、3 + 、和 4+ 龄。 5 + 和 5龄以上的高龄组所含比重很小 (<3 %)。雌性临产个体 (3 DF)的体长频数分布表明 ,大磷虾的初次性成熟年龄为 3龄。生殖群体也以 3 +龄为主 ,4+龄次之。种群组成存在着明显的地区差异。普里兹湾以北海域是典型的双态分布 ,1 + 龄占有相当大比重 ;测区东西两侧以成体虾为主 ,极少有 1 + 龄虾。种群组成的年际变化也是明显的 ,特别表现在补充群体 (1 + 龄 )

The results presented in this paper are based on the net sampling carried out on two marine science cruises,in 1989/1990 and 1990/1991 austral summer ,in Prydz Bay region by Chinese Antarctic R/V 'Jidi'.The population structures of Antarctic krill(Euphausia superba Dana)were studied.Length/Frequency distribution shows that krill population in this area mainly consists of four age groups,i.e.1 +,2 +,3 +and 4 +,except the larvae.5 +and >5 +age groups account for a very small proportion of the population (less than 3%).Regional differences in population structure are evident.Samples collcected from the north of the Prydz Bay presented typical bimodal L/F distribution,with a strong 1 +age group.Catches from the east and west part of the research area presented a monomodal L/F distribution,with the subadults and adults as the bulk of the population,no or very few juveniles appeared.Annual variation in population structure between the two years was obvious especially in the strength of 1 + age group.