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Results of the Japanese Abundance and Stock structure Survey in the Antarctic (JASS-A) during the 2019/20 austral summer season
Isoda, T., Katsumata, T., Yamaguchi, F., Ohkoshi, C. and Matsuoka, K.
International Whaling Commission
The results of the first survey of the Japanese Abundance and Stock structure Surveys in the Antarctic (JASS-A) are reported. A dedicated sighting vessel (SV) was engaged in the survey based on the line transect method for 25 days, from 13 January to 6 February 2020 in the western part of Area III (000?? - 015??E). The survey design was based on IWC/IDCR-SOWER survey procedures and two survey modes were used, Normal Passing mode (NSP) and Independent Observer mode (IO). The total searching distance in the research area was 1,447.9n.miles (2,681.5km), including 650.3n.miles covered in NSP mode and 797.6n.miles in IO mode. The survey coverage was 71% in the northern stratum and 83% in the southern stratum. Four baleen whale species, blue (19 schools/20 individuals), fin (72/136), Antarctic minke (119/203), humpback (90/168) and at least three toothed whale species, sperm (5/5), southern bottlenose (7/22) and killer (1/1) whales, were sighted in the research area. Blue whales were found mainly in the southern stratum of the research area. Fin whales were found mainly north of 64??S. Antarctic minke whales were the most frequently sighted whale species, and were mainly distributed near the ice edge and in the western side of the northern stratum. Humpback whales were widely distributed in the research area, and their distribution pattern was similar to that of fin whales. Estimated Angle and Distance Experiments were completed in the research area. Routine photo-ID and biopsy sampling on large whales were also conducted, and a total of 39 photo-IDs (20 blue, 14 humpback and 5 killer whales), were obtained. A total of 29 biopsy (skin and blubber) samples were also collected from 10 blue, 11 fin and 8 Antarctic minke whales using the Larsen system. Ten and eight satellite tags were deployed on fin and Antarctic minke whales, respectively. Oceanographic observation was conducted at 75 stations using the eXpendable Conductivity, Temperature and Depth (XCTD). An Argo float under the Argo oceanographic programme was successfully deployed at 40??13???S; 038??33???E. A total of three marine debris were observed in the research area. Data and samples collected in this survey will be analyzed in conjunction with data and samples obtained during past research programs in the Antarctic (JARPA, JARPAII, NEWREP-A), in the context of the primary and secondary objectives of the JASS-A.