- 著者
- イチイ タロウ Taro ICHII
- 雑誌
- Proceedings of the NIPR Symposium on Polar Biology
- 巻号頁・発行日
- vol.3, pp.36-56, 1990-03
Based on Japanese krill fishing and minke whaling data, the distribution of Antarctic krill (Euphausia superbd) concentrations was investigated in relation to bottom topography, sea-ice and hydrographic features. Data were from the Indian, Pacific and western Atlantic sectors. In early summer (December) high density concentrations of krill frequently occurred in the vicinity of southerly positioned pack-ice edges and in the embayments surrounded by the pack-ice edge. In mid and late summer (January-March) when the ice-edge was at its southern-most limit, krill fishing data indicated that harvestable areas were associated with the continental and insular shelf breaks, not with the pack-ice edge. Minke whaling data also suggested that not only sea-ice but also topographical features such as the continental shelf breaks and banks may be important factors affecting minke whale (Balaenoptera acutorostratci) distribution. Krill harvesting areas in the vicinity of the shelf breaks were often coincident with hydrographic fronts. These results suggested that hydrographic features caused by uneven bottom topography (e. g. shelf breaks or banks) may induce the formation of krill concentrations in mid and late summer. The extremely high concentration of minke whales and their food composition suggested the high abundance of E. superba around a bank on the Ross Sea shelf.
- 著者
- KOTORI Moriyuki NISHIYAMA Tsuneo TANIMURA Atsushi WATANABE Kentaro
- 出版者
- 国立極地研究所
- 雑誌
- Proceedings of the NIPR Symposium on Polar Biology (ISSN:0914563X)
- 巻号頁・発行日
- vol.1, pp.138-144, 1987-12
- 被引用文献数
- 2 4
Abundance, vertical distribution and maturity of the chaetognath Parasagitta elegans under the sea ice in a shallow lagoon (the depth of bottom, <20m) on Hokkaido in the daytime in February 1986, were examined. The abundance was estimated to be about 10-30 individ. m^<-3>. This is approximately half of the maximum densities previously reported in inshore open waters. Vertically, the maximum abundance was observed at a depth of 2 m beneath the undersurface of the ice. The size ranged 15.40-27.05 mm in body length, and most P. elegans were adult forms of Stage II in ovary maturity. These findings suggest that in the boreal waters P. elegans occurs commonly under the sea ice, and that the maturing adult forms appear in proximity of the ice even in the daytime.