Cruise report of the 2018 IWC-Pacific Ocean Whale and Ecosystem Research (IWC-POWER)
Koji Matsuoka, Jessica Crance, Amy James, Isamu Yoshimura and Hedenori Kasai
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 9th annual IWC-POWER cruise was conducted between 03 July and 25 September, 2018 in the central Bering Sea. The survey was conducted aboard the Japanese R/V Yushin-Maru No. 2. Researchers from the IWC, the US, and Japan participated in the survey. The survey was conducted using methods based on the guidelines of the IWC/SC. The acoustic survey was included for the 2nd 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 % (planned distance of 2,237.9 n.miles) of the original trackline, with a total of 1,685.5 n.miles in Passing with abeam closing mode (NSP) and Independent Observer passing mode (IO). Additionally, 421.6 n.miles were surveyed during transit between Japan and the research area. During the entire cruise, sightings of: blue (8 schools / 12 individuals), fin (135/199), sei (5/7), common minke (17/17), North Pacific right (3/3), humpback (86/122), gray (27/88), sperm (35/36), Bairdâ€™s beaked (2/24) and killer (20/136) whales were observed. Fin and humpback whales were the most frequently sighted large whale species. Gray whales were only sighted north of 64N. A solitary NP right whale was sighted north of 64N near St. Lawrence Island in the Central Bering Sea. There were no sightings of blue or sei whales in the Bering Sea. Photo-identification data were collected for 3 North Pacific right, 41 gray, 8 blue, 69 fin, 39 humpback, 33 killer and 4 sperm whales. Two of three right whale sightings were detected and localised using acoustics. A total of 76 biopsy (skin and sometimes blubber) samples were collected from 6 blue, 24 fin, 29 humpback, 7 gray, 3 North Pacific right and 7 killer whales using the Larsen sampling system. A total of 253 sonobuoys were deployed, for a total of almost 700 monitoring hours. Species detected include fin whales, detected on 46.5% of sonobuoys (101 buoys), sperm whales (72 buoys, 33.2%), killer whales (56 buoys, 25.8%), right whales (27 buoys 12.4%), and humpback whales (24 buoys, 11%). Other species detected include gray whales (10 buoys, 4.6%), Bairdâ€™s beaked whales (1 buoy, 0.5%), probable fish grunts (7 buoys, 3.2%), a double knock sound that we believe is attributed to fish (1 buoy, 0.5%), and possible earthquakes (2 buoys, 1%). A total of 19 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 9th annual cruise of this programme was successfully completed and provided important information on cetacean distribution, in particular gray, fin 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.