Cruise Report of the International Whaling Commission Pacific Ocean Whale and Ecosystem Research, 2017

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 8th annual IWC-POWER cruise was conducted between 03 July and 25 September, 2017 in the eastern part of the Bering Sea. The entire research area was within the US EEZ. 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 67a IWC/Scientific Committee (IWC/SC) meeting (IWC, 2017a). Researchers from Japan, the US and IWC participated in the survey. The cruise had five main objectives: (a) information for the in-depth assessments of North Pacific sei, humpback and gray whales in terms of abundance, distribution and stock structure; (b) 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 from the IWC-POWER cruises in 2010-12; (d) 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) 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 Captain and crew of the vessel and international researchers agreed on the procedures and objectives of the survey. The survey was conducted using methods based on the guidelines of the IWC/SC. The acoustic survey was introduced for the first 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 71.9 % (planned distance of 2,183.7 n.miles) of the original trackline with a total of 1,571.0 n.miles in the Passing with abeam closing mode (NSP) and the Independent Observer passing mode (IO). Additionally, 228.3 n.miles were surveyed during transit between Japan and the research area. Sightings of: fin (145 schools / 198 individuals), humpback (136/165), common minke (17/20), gray (15/22), North Pacific right (9 /18, including 2/3 duplicates), and sperm (25/33) whales were observed during the cruise. Fin and humpback whales were the most frequently sighted large whale species. Gray whales were sighted early in the survey, north of 64oN. There were no sightings of blue or sei whales during the cruise. The Estimated Angle and Distance Training Exercises and Experiments were completed. Photoidentification data were collected for: 15 North Pacific right (12 unique individuals, 3 duplicates), 14 gray (all unique), 55 fin, 34 humpback (32 unique individuals), 1 minke and 56 killer whales. These data are preliminary, pending further processing and photo-identification confirmation. The majority of North Pacific right whales were sighted at the western edge of Bristol Bay and in the middle of the critical habitat. Five of the nine right whale sighting were detected and localised using acoustics. A total of 60 biopsy (skin and blubber) samples was collected from 28 fin, 18 humpback, 9 gray, 3 North Pacific right and 2 killer whales using the Larsen sampling system. A total of 240 sonobuoys were deployed, for a total of 841 monitoring hours. Species detected include fin whales, detected on 46.7% of sonobuoys (112 buoys), killer whales (49 buoys, 20.4%), sperm whales (44 buoys, 18.3%), and right whales (38 buoys 15.8%), followed by humpback whales (23 buoys, 9.6%) and gray whales (4 buoys, 1.7%) and probable Cuvier’s beaked whale clicks (1 buoy, 0.4%). A total of 12 objects of marine debris were observed, considerably less than previous cruises. All survey procedures were in accordance with the guidelines set forth and agreed upon by the SC. The 8th annual cruise of this programme was successfully completed and provided important information on cetacean distribution, in particular gray and North Pacific right 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.