Cruise report of the 2021 IWC-Pacific Ocean Whale and Ecosystem Research (IWC-POWER)
Hiroto Murase, James W. Gilpatrick, Jr., Isamu Yoshimura and Hiroshi Eguchi
IWC-POWER is a joint research program between IWC and Japan conducted in the North Pacific, which has followed since 2011 IWC/IDCR-SOWER (Southern Ocean Whale and Ecosystem Research) that were conducted in the Antarctic Ocean from 1978 to 2010. The 12th annual IWC-POWER cruise was conducted between 2 August and 30 September 2021 in the eastern North Pacific (between 40?00?N and US and Canadian EEZ boundaries, 135?00?W and 155?00?W, comprised entirely of the High-Sea). The survey was conducted aboard the Japanese R/V Yushin-Maru No. 2. The cruise plan was endorsed at the 68C IWC/Scientific Committee (IWC/SC) meeting. Same as previous IWC-POWER cruises, the present cruise made a valuable contribution to the work of the IWC/SC on the management and conservation of populations of large whales in the North Pacific in a number of ways, including providing: (a) information for the ongoing assessments of North Pacific sei, humpback and gray whales in terms of abundance, distribution and stock structure; (b) information on endangered North Pacific right whales; (c) baseline information on distribution, stock structure and abundance for a poorly known area for other cetacean species/populations, including those that were known to have been depleted in the past but whose status is unclear; (d) essential information for the development of the medium-long term international programme in the North Pacific to meet the Commission?s long-term conservation and management objectives. At the pre-cruise meetings, the crew of the vessel and international researchers confirmed the objectives and agreed on the procedures of this survey. The survey was conducted using methods based on the guidelines of the IWC/SC. Survey trackline coverage was 77.2 % (1562.5 n.miles of a planned distance of 2,022.4 n.miles)., with a total of 833.7 n.miles in Passing with abeam closing mode (NSP) and 728.8 n.miles in Independent Observer passing mode (IO). During the entire cruise, sightings of: blue (6 schools / 7 individuals), fin (79/115), sei (25/40), Bryde?s (20/22), sperm (19/22) and killer (1/4) whales were observed. Blue and fin whales were mainly distributed in the northern part of the research area. Sei whales were distributed in mid-latitudes of the research area. Bryde?s whales were distributed in the southern part of the research area. North Pacific right whale was not sighted during the cruise. A total of 19 biopsy (skin and sometimes blubber) samples were collected from 3 blue, 9 fin, 4 sei, 2 Bryde?s and 1 killer whales. Photo-identification data were collected for: 7 blue, 31 fin, 15 sei 13 Bryde?s and 3 killer whales. These data are preliminary, pending further processing and photo-identification confirmation. No acoustic survey was conducted in the cruise. The Estimated Angle and Distance Training Exercise and Experiment were completed. A total of 88 objects of marine debris were observed. Feasibility experiment of dive behavior tagging was conducted at the discretion of Japan and the tags were deployed 2 fin and 3 sei whales. This cruise was successfully completed and provided important information on cetacean distribution, in particular blue, fin sei and Bryde?s whales, in a poorly-known and logistically difficult area, where limited survey effort had been made in the recent decades. These results will contribute to the aforementioned objectives of the IWC/SC.