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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Characteristics of the deep scattering layer in the Gulf of Mexico as they relate to sperm whale diving and foraging behavior

Azzara, Alyson Julie 15 May 2009 (has links)
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.
62

Temporal and Spatial Analysis of Killer Whale Sightings in the Galapagos Marine Reserve, Ecuador

Smith, Kerri 2012 May 1900 (has links)
A study was conducted using data compiled from two sources to test the hypothesis that killer whales display seasonal variability in their occurrence in the Galapagos Marine Reserve (GMR), Ecuador. Three questions arise from this hypothesis: 1) do killer whale sightings display temporal variability; 2) are sightings spatially associated with resources; and 3) if sightings are spatially associated with resources, does the spatial association change temporally? I combined and evaluated two sets of GMR killer whale sighting data (n=154) spanning a twenty-year time frame collected via opportunistic sightings by an observer network and shipboard line-transect surveys. I tested for a (a) correlation between the total annual sightings and bi-annual seasonality (upwelling versus non-upwelling); (b) correlation between the total annual sightings and the Multivariate El Nino Southern Oscillation Index (MEI); (c) correlation between sightings, the MEI, and seasonality; (d) spatial association between sightings and resources; and (e) spatial change in sightings with seasonality. Sightings were roughly equally distributed between non-upwelling (56%) and upwelling seasons (July-December). No direct correlation was found between sightings and the MEI. Sightings occurred more often than expected by chance during the peak upwelling months of August-November when the MEI was within one standard deviation of the average (binomial z=2.91, p<0.05). Sightings were spatially associated with areas of high chlorophyll a values (binomial z=4.46, p&lt;0.05), pinniped rookeries (binomial z=6.03, p&lt;0.05), and areas with high combined resource value (binomial z=5.36, p&lt;0.05). The spatial distribution of sightings did not shift with seasonality, with the exception that sightings occurred less often than expected in areas of low combined resource value during the upwelling period (binomial z=-3.17, p&lt;0.05). Though variability in observer effort should be considered when evaluating these data, these results do not suggest a strong pattern of seasonal occupancy or that killer whales are responsive to El Nino Southern Oscillation events. Further research is needed to determine if killer whales in the GMR comprise a single resident population, multiple resident and transient populations, or if killer whales observed in the GMR are part of a population inhabiting the eastern tropical Pacific region, which visit the area at various times.
63

Songs of a humpback whale (Megaptera novaeangliae) in Taiwan and evolution of communication in cetaceans

Yu, Hsin-Yi 09 September 2002 (has links)
Humpback whales (Megaptera novaeangliae) belong baleen whales. They migrate between high-latitude summer feeding regions and low-latitude wintering regions where calving and make place.There were 1~60 humpback whales whaled every year during 1920~1967 in southern Taiwan. However, only a few sights were recorded in the past twenty years. A male humpback whale was sighted on the east coast of Taiwan in March, 2000. His songs recorded during between three-day tailing were analysed. There were five themes and nine units in the songs, a complete song duration lasted about 14.2 minutes. The maximal sound pressure level was 189.6 dB (n=32, SEM =2.81). The acoustic characters (i.e., signal duration, time between two signals, theme duration, fundamental frequency) of the songs were not significant different. A visual comparison of the spectrograms of the sound units from this particalar whale with those northwest Pacific Ocean showed similarity. This individual was a member of the population in the northwest Pacific Ocean. This conclusion was also supported by the result of Photo-ID of its fluke. Ceatceans live in the water and develop the special model to produce sounds. There are two kinds of communicative signals: pulses and whistles. These two signals were characters of phylogenetic relationship and the outgroup was red deer. There were two monophyletic groups. Evolution of communicative signals in cetaceans was whistle existent and added the pulses signals. Last, the whistles lost and only with pulses. The fumctions of pulse signals in communication was unknown in delphinidae. Sperm whales, pygmy sperm whales, dwarf sperm whales, Baird¡¦s beaked whales and Hector¡¦s dolphins were only use pulse signals. The reason of this change was unclear.
64

Spatial distribution of rorqual whales in the Strait of Jacques Cartier, Gulf of St. Lawrence, Quebec, Canada

Doniol-Valcroze, Thomas. January 2001 (has links)
The spatial distribution of four species of rorqual whales was studied along the north shore of the Gulf of St. Lawrence during the months of June to October from 1989 to 2000. A research effort of 6511 hours at sea yielded 849 sightings of blue whales (Balaenoptera musculus), 5291 of finback whales (Balaenoptera physalus), 3822 of humpback whales (Megaptera novaeangliae) and 6489 of minke whales (Balaenoptera acutorostrata). Spatial and behavioural data were collected at sea using inflatable boats, and Global Positioning Systems (GPS) were used to obtain accurate positions. These data were plotted and analysed using a Geographic Information System (GIS) to test the hypotheses that patterns of distribution were not random, were associated with bathymetry and reflected specific differences in habitat use. The resulting maps illustrated the clustered distribution of rorqual whales linked to sea-bottom topography, probably associated with areas of local upwelling and increased productivity. Blue and fin whales shared almost the same distribution, humpback whales were found in slightly deeper, offshore waters whereas minke whales were more abundant in shallower waters. Little attention has been given until now to local patterns of distribution in the area and such information can be useful for practical management considerations. The results emphasise the importance of scale in ecological studies of marine mammals and the need for further research using additional oceanographic parameters, in order to better understand habitat selection.
65

The deglaciation and postglacial marine emergence of the Little Whale River area, New Quebec.

Archer, David Ronald. January 1966 (has links)
Fluctuations of sea level in the recent past are well documented in the landscapes of northern Canada by the existence of raised strandlines with marine shells and emerged off-shore deposits. However details of these fluctuations in many areas remain to be resolved and their relationship to glaciation and deglaciation needs to be determined. [...]
66

Sperm whale diet in New Zealand

Gómez-Villota, Felipe Unknown Date (has links)
Stomach contents of 19 mature sperm whales, 18 males and one female, that stranded on New Zealand beaches between the mid 1990s and 2004 were examined, identified and measured. Three of the stomachs were empty. All other samples consisted almost entirely of cephalopod beaks. A total of 23,223 cephalopod beaks (10,647 upper and 12,576 lower), representing at least 36 species in 17 families were found in the remaining 16 stomachs. Non-cephalopod remains in the stomachs of sperm whales stranded in New Zealand included limited quantities of fish, salps, crustacean exoskeletons, a copepod, some wood and sand.The present investigation represents the most comprehensive study of the diet of sperm whales in New Zealand since the early 1960s. The results show that oceanic squid of the families Histioteuthidae, Cranchiidae, Onychoteuthidae and Octopoteuthidae are the most common remains found in the stomachs of sperm whales stranded on New Zealand beaches, with the families Onychoteuthidae, Histioteuthidae, Octopoteuthidae and Architeuthidae being the most important by estimated weight in whale diet, and the families Cranchiidae, Pholidoteuthidae and Ancistrocheiridae secondarily so.The beaks of three cephalopod species thought to be restricted to Antarctic waters (Kondakovia longimana, Mesonychoteuthis hamiltoni and Psychroteuthis glacialis) were found in 12 of the stomachs, suggesting these whales had recently migrated into New Zealand from more southern feeding grounds. The amount of local cephalopod beaks in the stomachs suggests some of the stranded sperm whales did not feed much within New Zealand waters in the days prior to stranding.The beaks of Taningia danae, Octopoteuthis megaptera, Octopoteuthis sp. 'Giant' and Lepidoteuthis grimaldii are illustrated and described. Oblique and lateral illustrations of the lower beaks are given, as well as sections of the rostrum, jaw angle, shoulder and lateral wall, to show the major identifying features for each of the species.Squid are an important component of food chains in the Southern Ocean and they act as both high-level predators and prey for apex predators. Therefore, seasonal fluctuations in their abundance must have cascading effects on the diets of apex predators. With increasing global fishing effort, and with cephalopods representing over 4% of the global annual catch, there are competing interests between the ocean's top teuthophagous predators and the fishing industry.Uncertainty of the effects fisheries have on the marine ecosystem has stimulated numerous research studies in recent years. However, despite the economic and ecological importance of cephalopods, there are few ecological studies on them or their significance in the trophic systems of the deep-sea and their life cycles and distribution patterns are only now beginning to be understood. Additional dietary studies that investigate the cephalopod composition and size-class structure in the diet of predators are needed to assess their importance in deepsea food webs, and the potential impact that deep-sea fisheries might have on associated and dependant species, namely apex oceanic predators.The results of this study provide the first significant insight into the diet of the sperm whale, one of the most important apex predators in New Zealand waters.
67

Assessing the status of the endangered North Atlantic right whale using genetic and demographic data /

Waldick, Ruth. January 1999 (has links)
Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references. Also available via World Wide Web.
68

An environmental profile : the whale watchers of Encounter Bay, South Australia /

Reid, Elizabeth. January 1993 (has links) (PDF)
Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1994. / Includes bibliographical references (leaves 96-102).
69

Mercury and selenium in beluga teeth tools for biomonitoring and dietary exposure assessment /

Kinghorn, April. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Natural Resource Science. Title from title page of PDF (viewed 2008/01/15). Includes bibliographical references.
70

Maintaining contact : design and use of acoustic signals in killer whales, Orcinus orca /

Miller, Patrick J. O. January 1900 (has links)
Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology, and the Woods Hole Oceanographic Institution), 2000. / Vita. Includes bibliographical references.

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