Euphausiids collected from the Australian Sector of the Southern Ocean during the BIOMASS SIBEX cruise (KH-83-4)

• Main Authors: Terazaki,Makoto, Wada,Masako
• Format: Report
• Language: English
• Published: Ocean Research Institute, University of Tokyo/Ocean Research Institute, University of Tokyo 1986
• Subjects: Antarctic; Kidd; Southern Ocean; The Antarctic; Antarc*; Euphausia superba; Memoirs of National Institute of Polar Research; Polar Research; Thysanoessa macrura
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1880; http://id.nii.ac.jp/1291/00001880/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1880&item_no=1&attribute_id=18&file_no=1

Euphausiids were collected in the Australian Sector of the Southern ocean during the BIOMASS SIBEX cruise (KH-83-4), with a 10-foot Isaacs-Kidd Midwater Trawl. The biomass of euphausiids in the epi- and mesopelagic layers of the Southern Ocean was 0.58-16.96g (wet wt.) per 1000m^3 and the total number of individuals was 6.8-103.1/1000m^3,accounting for 1.3-11.2% of the total biomass. Generally, the biomass and the total number of euphausiids in the Subtropical Water were the smallest in the Southern Ocean. Six genera including 18 species occurred, and Thysanoessa macrura, Euphausia superba, E. triacantha, E. crystallorophias and E. frigida were collected from the Antarctic Zone. A total of 270 surface swarms were observed by sighting survey at 62°S and southward in the Antarctic Zone. The surface swarms of E. superba consisted almost exclusively of immature individuals, 22-25mm in mean body length. The density of these swarms was 147-778g/m^3. As a result of a parallel grid survey by using the acoustic system, many scattering layers appeared at the depth between 10 and 100m. The main organisms scattering were adults of E. superba and T. macrura. The evidence of mating of E. superba was recognized in the females larger than 38mm in body length and the occurrence of many females with spermatophores attached suggests that they were in the main breeding season.