Abstract:

The data used in this paper was obtained from the comprehensive oceanographic survey during the First Chinese National Arctic Research Expedition in Chukchi Sea and Bering Sea in July and August 1999. The characteristics of ecological groups, species composition, horizontal and vertical distribution of Chaetognatha in both Chukchi Sea and Bering Sea are described and the relationships of Chaetognatha density and some other environmental factors are discussed. The results show that seven species of Chaetognatha were recorded which belongs to 3 ecological groups. The number of Chaetognatha was higher in Bering Sea than in Chukchi Sea. The density of dominant species determined the total Chaetognatha abundance and it was higher in south than in north. The density was high in water layer of 50-200m and low in water layer of 500 -800m in Chukchi Sea. In the other hand, the density was comparatively high in layers of 200-500m in Bering Sea during the daytime and aggregated in water layers 0-100m, particularly in 0-50m during the night, showing a pattern of up and down migrations in day and night, respectively.