North Pacific Right Whale (Eubalaena japonica) Seasonal and Diel Calling Patterns from Long-Term Acoustic Recordings in the Southeastern Bering Sea, 2000–2006

Authors

Lisa Munger, Scripps Institution of Oceanography, University of California, San Diego
Sean Wiggins, Scripps Institution of Oceanography, University of California, San Diego
Sue Moore, NOAA, Alaska Fisheries Science Center
John Hildebrand, University of California, San Diego, 9500 Gilman Drive, mail code 0205, La Jolla, California

Date of this Version

10-2008

Comments

Published in MARINE MAMMAL SCIENCE, 24(4): 795–814 (October 2008).

Abstract

We assessed North Pacific right whale (Eubalaena japonica) seasonal and daily calling patterns in the southeastern Bering Sea (SEBS) using long-term hydrophone recordings from October 2000 through January 2006. We detected right whale calls on the SEBS middle shelf (<100 m depth) as early as May, intermittently throughout summer and fall, and as late as December. Calls also were detected on one day in June 2005 on the SEBS slope (>1,000 m), but were not detected near Kodiak Island from April to August 2003. In months with calls, detections occurred on more days in July–October (≥6 d/mo), than from May to June or November to December (≤3 d/mo). Calls were clustered in time and were usually detected on 1–3 consecutive days with a median interval of 6.5 d for calls >1 d apart. Hourly calling rates were significantly higher at night than during the day. These data indicate that right whales occur in the SEBS later in the year than previously known, intermittently pass through the middle-shelf study region, and usually remain there no longer than a few days. Right whale habitat use in the SEBS may intensify in mid-summer through early fall based on higher monthly and daily call detection rates.