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SC/69A/ASI/13
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Resource ID
19942
Access
Open
Document Number
SC/69A/ASI/13
Full Title
Results of the Japanese Abundance and Stock structure Survey in the Antarctic (JASS-A) during the 2022/2023 austral summer season
Author
Tatsuya Isoda, Taiki Katsumata, Yujin Kim, Chikara Omukai, Seiichiro Teruya, Marin Miyagi, Reiko Nagata, Hidenori Kasai, Nobuo Abe And Koji Matsuoka
Authors Summary
This paper describes the results of the sighting survey of the Japanese Abundance and Stock structure Survey in the Antarctic (JASS-A) conducted using line transects and distance sampling methods from 10 January to 6 February 2023 in the western part of Area VI East (145°-130°W). The survey included coastal ice-free areas, south of 71°30'S and the total effort was 2,168.6 nautical miles. In addition to collecting systematic sighting and oceanographic data, biopsy, photo-ID, and satellite tracking experiments were conducted.
Publisher
IWC
Publication Year
2023
Abstract
The results of the fourth survey of the Japanese Abundance and Stock structure Surveys in the Antarctic (JASS-A) are reported. Two dedicated sighting vessels (SVs) were engaged in the survey based on the line transect method for 28 days, from 10 January to 6 February 2023 in a part of Area VI East (145°–130°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 71°30'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 2,168.6n.miles (4,016.2km), including 1,051.1n.miles covered in NSP mode and 1,117.57n.miles in IO mode. The survey coverage was 76% in the northern stratum, 91% in the southern stratum and 75% in the coastal ice-free waters. Four baleen whale species, Antarctic blue (20 schools/31 individuals), fin (59/137), Antarctic minke (242/521), humpback (21/46) and at least two toothed whale species, sperm (7/7), and killer (11/117) 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 74 photo-IDs (26 Antarctic blue, 11 humpback and 37 killer whales) were obtained. A total of 89 biopsy samples were collected from eight Antarctic blue, 20 fin, 28 Antarctic minke, six sei, 16 humpback, two pygmy right and nine killer whales during the whole survey. Satellite tags were deployed on eight fin, 25 Antarctic minke, two sei, two humpback and one pygmy right whales during the whole survey. Oceanographic observations were conducted at 137 casts using the eXpendable Conductivity, Temperature and Depth (XCTD). Nine 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.