南极斯科舍海南极磷虾种群雌性群体结构时空变化

Spatio-temporal variability in stock structure of female Antarctic krill(Euphausia superba)in the Scotia Sea,Antarctic

斯科舍海是南极磷虾资源分布最为密集的海域,也是磷虾渔业的传统渔场,但该海域磷虾种群结构较为复杂且多变,而种群中的雌性群体对于种群的结构稳定与规模维持极为关键。为了解该海域磷虾资源中雌性群体的结构与动态,利用2016—2022年1—9月由渔业调查随机收集的样本,对该海域雌性磷虾群体的结构时空变动进行了分析。结果显示,各年间雌性磷虾的发育阶段存在显著差异,2016—2022年间,磷虾种群中主要以亚成体占优,其次为成体,而幼体的比例较低。从性腺成熟度年变化来看,亚成体2FC和2FD个体的比例多高于2FB个体。季节上,冬春季的群体结构较为简单,而夏秋季的种群结构非常复杂,冬季亚成体比例占绝对优势。此外,各区域(南极半岛、南奥克尼群岛和南乔治亚岛)间的雌性磷虾群体结构存在差异;南奥克尼群岛区域的成体比例最高(65.4%),而南乔治亚岛区域的亚成体在种群中占绝对优势(89.9%),未出现幼体。

The Scotia Sea is the most densely distributed area of Antarctic krill(Euphausia superba)resources,and is also the traditional fishing ground for krill fishery,but population structure of krill is complex and varies widely in this region.It plays the key role of females in the population for stabling structure and maintaining size of population.In order to understand the population dynamics of krill in this region,the temporal and spatial variability in female stock of krill resource in this region was analyzed using samples randomly collected by fishery surveys from January to September,2016 to 2022.The results showed that there were significant differences in the development stages of krill annually.During 2016-2022,female krill stock was mainly dominated by subadults,followed by adults,and the proportion of juveniles was low.For the perspective of the annual variation of sexual maturity,the proportions of subadults(stages 2FC and 2FD)were generally higher than that of stage 2FB individuals.In terms of seasons,the female stock structure was relatively simple in winter and spring,while that was very complex in summer and autumn,the subadults was predominant in the stock.In addition,the structure of female krill stock was different between regions,the proportion of adults in the South Orkney Islands was the highest(65.4%),while the subadults was predominant in the stock(89.9%)and no juveniles occurred at South Georgia.