Results of the Japanese Abundance and Stock structure Survey in the Antarctic (JASS-A) during the 2021/2022 austral summer season
Tatsuya Isoda, Taiki Katsumata, Eisei Ueta, Hidenori Kasai and Koji Matsuoka
The results of the third 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 33 days, from 11 January to 12 February 2022 in the eastern part of Area VI East (130?W?120?W). For the survey, the research area was divided into northern and southern strata. In addition, surveys were conducted successfully in coastal ice-free waters, south of 72?S, an area that is normally covered by pack-ice and therefore of difficult access to vessels. 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 1,333.5n.miles (2,469.6km), including 659.0n.miles covered in NSP mode and 674.4n.miles in IO mode. The survey coverage was 62% in the northern stratum, 92% in the southern stratum and 83% in the coastal ice-free waters. Four baleen whale species, Antarctic blue (5 schools/6 individuals), fin (44/64), Antarctic minke (83/142), humpback (26/36) and at least four toothed whale species, sperm (9/10), southern bottlenose (1/1), Arnoux?s beaked (1/8) and killer (5/71) whales, were sighted in the research area. Antarctic minke whales were the most sighted whale species. This species was also frequently sighted in the coastal ice-free waters. Fin and humpback whales were the second and third most sighted species, respectively and both species were found only in the northern stratum. Estimated Angle and Distance Experiments were completed in the research area. Routine photo-ID and biopsy sampling on large whales were also conducted during the whole survey (including transit). A total of 26 photo-IDs (seven Antarctic blue, nine humpback and ten killer whales) were obtained. A total of 43 biopsy samples were collected from two Antarctic blue, 12 fin, 15 Antarctic minke, 11 humpback, one Bryde?s (in the transit area) and two killer whales. Nine and 15 satellite tags were deployed on fin and Antarctic minke whales, respectively. Oceanographic observations were conducted at 116 casts using the eXpendable Conductivity, Temperature and Depth (XCTD). One marine debris was 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.