Monitoring cetaceans in the North Pacific

Abstract

Two projects were undertaken in order to monitor cetaceans in the North Pacific. The first was designed to obtain passive acoustic data from the U.S. Navy's Northern Edge Range. Three instruments were deployed in April 2008 to monitor both high (up to 25 kHz) and low (up to 1 kHz) frequencies for odontocetes and mysticetes, respectively. Unfortunately, these instruments did not record any data. The second project was to analyses retrospective data obtained by analysts at the Whidbey Island NAVFAC for broad regions of the North Pacific. Long-term (1996-2002) trends of blue and fin whale vocalizations were found to have strong seasonal and geographic differences. Furthermore, the number of fin whale call events detected increased significantly over time throughout the North Pacific. Onset and continuation of fin whale calling seemed to be primarily driven by day length, while blue whale calling behavior was influenced by combinations of sea surface temperature, surface chlorophyll a concentration, and day length.