This research was carried out in support of fieldwork in the Gulf of Mexico in summers
2004 and 2005 as part of the multidisciplinary Sperm Whale Seismic Study (SWSS).
Important aspects of SWSS research include oceanographic habitat characterization and
studies of sperm whale foraging and diving patterns. During the SWSS 2005 cruise,
acoustic volume backscatter data were collected using a 38 kHz ADCP for comparison
with XBT, MODIS ocean color data, and whale dive profiles extrapolated from analysis
of towed passive acoustic hydrophone array recordings of whale vocalizations. This
unique data set, collected from a cyclonic eddy, was compared with non-upwelling
conditions surveyed in the western Gulf and the Mississippi Canyon in summer 2004.
My focus was to examine the relationship between acoustic backscatter intensity from the
deep scattering layer (DSL; usually 400-600 m deep) and the depths to which whales
dived. The results of the study investigate differences in DSL characteristics between
divergent zones and non-divergent zones, and examine connections relating to variations
in sperm whale dive patterns. The analysis of 38 kHz ADCP data showed that there were significant differences in some characteristics of the main DSL dependent on time of day.
There were no significant differences in characteristics of the main DSL between
divergent and non-divergent areas or between 2004 and 2005. The comparison of the 38
kHz ADCP and the 70 kHz Simrad echosounder data yielded a relationship of 4 ADCP
counts for every 1 dB of Sv. This relationship was a promising start to a potential
calibration for the ADCP instrument. Lastly, the analysis of localized sperm whale dive
profiles identified three basic dive profiles; Deep (> 800 m), Mid-water dives to DSL
depths (500 - 800 m) and Shallow (<500 m). The analysis also showed that whale dive
behavior did not change based on time of day or location. It showed that whales are
diving above the DSL as well as through and below, however these dives are independent
of differences in DSL characteristics.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1173 |
| Date | 15 May 2009 |
| Creators | Azzara, Alyson Julie |
| Contributors | Biggs, Douglas, DiMarco, Steven |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
Page generated in 0.0018 seconds