Cruise report of the 2019 IWC-Pacific Ocean Whale and Ecosystem Research (IWC-POWER)
Koji Matsuoka, Jessica Crance, James W. Gilpatrick, Isamu Yoshimura and Chikamasa Ohkoshi
International Whaling Commission
IWC-POWER cruises in the North Pacific follow the series of IWC/IDCR-SOWER (Southern Ocean Whale and Ecosystem Research) cruises that were conducted in the Antarctic since 1978. The 10th annual IWC-POWER cruise was conducted between 03 July and 25 September, 2019 in the Gulf of Alaska, within the U.S. Exclusive Economic Zone. The survey was conducted aboard the Japanese R/V Yushin-Maru No. 2. The cruise was organized as a joint project between the IWC and Japan. The cruise plan was endorsed at the 67B IWC/Scientific Committee (IWC/SC) meeting. Researchers from the IWC, the U.S., and Japan participated in the survey. The cruise had five main objectives: (a) obtain information for in-depth assessments of North Pacific sei, humpback and gray whales in terms of abundance, distribution and stock structure; (b) obtain information on the critically endangered North Pacific right whale population in the eastern Pacific; (c) completion of coverage of the northern range of fin whales following on the IWC-POWER cruises in 2010-12; (d) obtain baseline information on distribution, stock structure and abundance for a poorly known area for several large whale species/populations, including those that were known to have been depleted in the past but whose status is unclear; (e) obtain essential information for the development of the medium-long term international programme in the North Pacific in order to meet the Commission???s long-term objectives. At the pre-cruise meeting, the crew of the vessel and international researchers agreed on the procedures and objectives of this survey. The survey was conducted using methods based on the guidelines of the IWC/SC. The acoustic survey was included for the 3rd time to acoustically monitor for the presence of marine mammals, with particular importance for detecting and locating North Pacific right whales. Survey trackline coverage was 75.3 % (2,118.7 of a planned distance of 2,476.2 n.miles), with a total of 1,091.4 n.miles in Passing with abeam closing mode (NSP) and 1,027.4 n.miles in Independent Observer passing mode (IO). Additionally, 636.7 n.miles were surveyed during transit between Japan and the research area, and transit within the research area. During the entire the cruise, sightings of: blue (18 schools / 20 individuals), fin (239/405), sei (25/42), common minke (6/6), humpback (147/289), gray (6/15), sperm (36/47), Baird???s beaked (2/37) and killer (50/248) whales were observed. Blue whales were widely distributed in the research area. Fin and humpback whales were the most frequently sighted large whale species. Sei whales were mainly sighted in the western part of the research area. Gray whales were only sighted near south of Kodiak Is. No North Pacific right whales were seen, although they were acoustically detected. Photo-identification data were collected for: 6 gray, 16 blue, 51 fin, 30 humpback and 19 killer whales. These data are preliminary, pending further processing and photo-identification confirmation. A total of 75 biopsy (skin and sometimes blubber) samples were collected from 2 gray, 12 blue, 45 fin, 4 sei and 12 humpback whales. A total of 229 sonobuoys were deployed, for a total of over 820 monitoring hours. Species detected include fin whales, detected on 56.1% of sonobuoys (119 buoys), sperm whales (112, 52.8%), killer whales (76, 35.8%), blue whales (54, 25.5%), humpback whales (47, 22.2%), North Pacific right whales (10, 4.7%), and sei whales (4, 1.9%). Other species detected include Baird???s beaked whales (3, 1.4%), Pacific white-sided dolphins (3, 1.4%), earthquakes (33, 15.6%), and unknown calls/signals (12, 5.7%). Although North Pacific right whale gunshot calls were detected in their Critical Habitat at the end of the survey, the animal was never sighted due to inclement weather and infrequent calling. The Estimated Angle and Distance Training Exercise and Experiment were completed. A total of 42 objects of marine debris were observed. This cruise was successfully completed and provided important information on cetacean distribution, in particular blue, fin and sei whales, in an area where limited survey effort had been conducted in recent decades, in a poorly-known and logistically difficult area. These results will contribute to the aforementioned objectives of the IWC/SC.