| Oceanography > Issues > Archive > Volume 15 > Issue 3 |
2002, Oceanography 15(3):20–25, http://dx.doi.org/10.5670/oceanog.2002.11
Blue Whale Habitat Associations in the Northwest Pacific: Analysis of Remotely-Sensed Data Using a Geographic Information System
Authors | First Paragraphs | Full Article | Citation
Authors
Sue E. Moore | NOAA/Alaska Fisheries Science Center, Seattle, Washington, USA
William A. Watkins | Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
Mary Ann Daher | Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
Jeremy R. Davies | NOAA/Northwest Fisheries Science Center, Seattle, Washington, USA
Marilyn E. Dahlheim | NOAA/Alaska Fisheries Science Center, Seattle, Washington, USA
First Paragraphs
Detection of stereotypic call sequences are now commonly used to locate blue whales (Balaenoptera musculus) in the North Pacific (e.g., Watkins et al., 2000a; Stafford et al., 1998; 2001; McDonald et al., 1995). Offshore hydrophones, such as those of the U.S. Navy Sound Surveillance System (SOSUS), have extended our monitoring capability to unprecedented spatial and temporal scales, providing the foundation for descriptions of basin-wide seasonal call patterns (Stafford et al., 1999; Clark, 1995). Consistent seasonal patterns of blue whale calling have been described for both the Northeast (NE) and Northwest (NW) regions of the Pacific basin (Watkins et al., 2000a), with clear differences in call structure suggestive of separate populations (Stafford et al., 2001). Overall, blue whale calls were two to three times more numerous in the NW region (40°N to 55°N latitude, between 150°E and 180°W longitude) than in other regions of the North Pacific, with consistently high calling rates from August through November (Watkins et al., 2000a: Figure 1). Monthly summaries of call occurrence and seasonal depictions of blue whale call locations (Watkins et al., 2000b) demonstrated the year-round occurrence of blue whales in the NW Pacific, with the fall-winter period showing the strongest signal. This was surprising because it belied the oft-repeated assumption that all blue whales migrate south in fall to winter, at temperate latitudes, and occupy North Pacific waters only in late spring and summer (e.g., Bowen and Siniff, 1999). Clearly, the NW Pacific presents suitable habitat for blue whales year-round, although the actual number of whales producing the calls remains unknown.
Environmental and habitat features are examined here to investigate oceanographic correlates to the seasonal variability in blue whale call rates and locations in the NW Pacific. Bathymetry and remotely sensed oceanographic data (i.e., sea surface height, temperature and chlorophyll-a concentration) were compared with call data locations via a geographic information system (GIS). The GIS provides the means to integrate remotely sensed acoustic and satellite data over very broad temporal and spatial scales. The results serve to demonstrate the potential of GIS as a tool for the investigation of habitat associations for blue whales in a remote area and at ecological scales for which standard survey techniques are impractical.
Full Article
Citation
Moore, S.E., W.A. Watkins, M.A. Daher, J.R. Davies, and M.E. Dahlheim. 2002. Blue whale habitat associations in the Northwest Pacific: Analysis of remotely-sensed data using a geographic information system. Oceanography 15(3):20–25, http://dx.doi.org/10.5670/oceanog.2002.11.