Thesis (M.Sc.(Zoology and Entomology))--University of Pretoria, 2008. / The thesis is structured as three separate papers to be submitted to journals for publication, with a single reference list at the end. Includes bibliographical references (leaves 130-147).

No description available.

Lack of knowledge regarding beaked whale biology restricts our ability to evaluate their vulnerability to anthropogenic threats. This work addresses critical data gaps in Blainville's beaked whale social structure and communication systems. Social analysis shows that Blainville's beaked whales in the Bahamas exhibit group living through a harem structure characterised by a single male accompanying a group of females for up to a year. This study also reveals that females preferentially associate with conspecifics in the same reproductive state, remaining together for up to three years. I show what may be the first example of social philopatry in beaked whales, with adult males possibly providing protection for kin. Analysis of data from acoustic tags reveals previously undescribed sexually distinctive vocalisations. These sounds might serve a communicative function helping to form and maintain groups. Acoustic data also reveals a distinctive double click pattern in Blainville's beaked whales that is likely physiological in nature. The same pattern is also shown in two other deep diving species, Cuvier's beaked whales and sperm whales. Species differences in the frequency of production of these double clicks may be providing a window into the evolution of odontocete echolocation. Data from a bottom-mounted hydrophone array reveals a lack of sex and / or age specific information in this species' echolocation clicks. Analysis of mother-calf pairs indicate calves from at least three months of age echolocate using clicks similar to those of adults. This work provides the first comprehensive study of possible communicative sounds in an elusive deep-diving cetacean species exhibiting a complex social structure that lies somewhere between stable groups and fission-fusion societies. Understanding the interaction between communication and social organisation enhances our ability to predict the effects of anthropogenic disturbance on this species.

Field observations were collected to assess the social behaviour and foraging strategies of free-ranging killer whales from the eastern North Pacific (near Vancouver Island, Canada) and the western South Atlantic (near Peninsula Valdez, Argentina). The Vancouver Island study concentrated on the environmental correlates of group size and the behavioural dynamics of social groups. There were no correlations between foraging behaviour and small-scale habitat use, however both group size and the spatial distribution of groups were correlated with foraging behaviour. In Argentina the subject whales intentionally stranded to capture pup sea lions. It was possible to observe details of prey choice and foraging strategy. Three social groups were observed in the study area. Area use suggested that the different groups were employing different strategies. Whales within social groups shared prey, but one group would exclude another from the best hunting areas. Whales invested the greatest effort in the area of highest yield, and on the prey-type that required the least effort to catch. Energetic calculations suggested that the rate at which these whales captured sea lion prey was just sufficient to sustain them. Two genetic components, the hypervariable 'minisatellite' loci, and the mitochondrial genome were investigated for each study population. In addition, further samples from Iceland and other populations near the sites at Peninsula Valdez and Vancouver Island were analysed. Whales within social groups at Peninsula Valdez were more closely related than between social groups. In general, whales within local populations had very high levels of genetic similarity compared to between population comparisons. This implies inbreeding within and genetic isolation between populations. Two genetically isolated populations (both near Vancouver Island) were sympatric, and the degree of genetic isolation was equal to the level seen for comparisons between the Atlantic and Pacific. A hypothesis is presented on the role of resource exploitation in the structuring of social groups, and the consequences for the genetic structuring of populations.

Whale-watching tourism depends upon the continued presence of cetacean species within a specific area. However, current evidence suggests that the distribution and/or abundance of cetaceans may alter in response to continued changes in sea surface temperature with global climate change (GCC). This thesis develops and applies a framework for evaluating the resilience of whale-watching tourism to these potential temperature-induced shifts in cetacean distribution. The framework identifies three key components that are likely to affect the vulnerability of an operator to climate change impacts on cetacean occurrence (and tourist numbers). These are the likelihood of observing a cetacean, the type of whale-watching trip, and the type of tourist. Together with an examination of an operator's adaptive capacity, these data provide the type of information required to make an assessment of resilience. Using Western Scotland as a case study, framework components were populated using species distribution modeling, a motivation-based segmentation of whale-watchers, an examination of tourist's attitudes to scenarios of a changing environment and a segmentation of trip activity. Finally, data on potential vulnerability were combined with investigation of an operator's adaptive capacity (using semi-structured interviews) to make an evaluation of resilience to climate change. Our results highlight four key findings: (1) operators have high inherent resilience to a variable environment in which uncertainty is accepted, (2) vulnerability to climate change is influenced by the type and number of trips offered by whale-watch operators, (3) adaptive capacity can be improved through enhanced perceptions of risk, and (4) vulnerability to climate change is not independent from vulnerability to other factors. Future research should focus on those areas where whale-watching is less diverse, more specialised and where, currently, the climate is less variable, as it is in these regions that vulnerability may be highest and, most likely, capacity to develop resilience at its lowest.

Thesis (Ph. D.)--University of Florida, 1979. / Vita. Typescript. Includes bibliographical references (leaves 189-199).

The vital rates of beluga, Delphinapterus leucas, harvested in northern Quebec are within the range reported by previous studies in Alaska and the Canadian and Soviet Arctic. Small sample size and inadequate estimates of survivorship rates prevent meaningful calculation of population growth rate. The pattern of changes in vital rates over the life cycle of beluga and analysis of errors associated with stage classification indicate that the demographic information in a 6 x 6 age-grouped Lefkovitch matrix is similar to that in a 38 x 38 age class Leslie matrix. A 3 stage, length-based model composed of newborns, juveniles and adults contains less demographic information than the larger matrices, but is superior to a juvenile/adult classification scheme. The 3 stage model applied to length frequency data from aerial photographic censuses should provide an alternate method of demographic analysis when harvests are small or absent. Colour is a poor criterion for stage classification. / Sensitivity analysis of fecundity and survivorship indicates that survival of gray animals (older juveniles and early breeders) has the most influence on population growth rate. Changes in fecundity have little effect on growth rate. The high sensitivity of population growth rate to juvenile and early adult survival demonstrates that these estimates should be improved if more precise knowledge of beluga demography is required for management purposes. / The age-length data used to evaluate errors associated with stage classification indicate that belugas in Hudson Bay are smaller than those elsewhere, but not to the large degree previously reported. Beluga in estuaries are represented by all size classes. Examination of the integumentary heat loss show beluga and narwhal, Monodon monoceros, to be equally insulated, but only belugas frequent warmer estuarine waters.

No description available.

In this thesis I take a multi-disciplinary approach to identify and characterise ‘Evolutionary Significant Units’ (ESUs) and ‘Management Units’ (MUs) of killer whale in the eastern North Atlantic. Several markers and traits including mitochondrial DNA control region, 15N stable isotope values, tooth wear, tooth count, total body length and pigmentation pattern indicated sympatric lineages could be categorized in to two ecologically & morphologically disparate types, which should be considered as distinct ESUs. One type (type 2) appears to be a specialist and may predate cetaceans. The other type (type 1) appears to be a generalist, although the total niche width of the population appears to be more dependent upon between-individual variation than within-individual variation in dietary composition. However, the other indicator of long-term diet, apical tooth wear, was found in all type 1 individuals, suggesting some overlap in the components of the diet. There are shallow genetic differences between the two types based on mtDNA control region, however analysis of bi-parentally inherited nuclear DNA markers are needed to see if the two types are reproductively isolated. The data above on diet is further supported by observational data of individuals moving between the Icelandic herring grounds to the seal pupping haul-outs around the Northern Isles, Scotland. However, large scale movement of individuals is mostly correlated with the movement of large predictable prey stocks such as the Icelandic and Norwegian stocks of Atlantic herring. Therefore there is the potential for prey choice to cause intrinsic isolation through temporal or spatial isolation even when the prey type is similar, e.g. mackerel, Icelandic herring or Norwegian herring. The microsatellite data are consistent with this pattern and taken together the genetic and mark-recapture data identify four demographically independent MUs of type 1 killer whales. We only identify one community or MU of type 2 killer whales, which is small (10 individuals) and appears to be suffering from demographic stochasticity. Our results suggest intrinsic isolation through temporal and spatial isolation as the most parsimonious mechanism for reducing gene flow between populations of the same type. Further work is needed to determine if there is gene flow between types or if adaptive divergence feeds back to reduce gene flow through mate choice.

Thesis (Ph. D.)--University of Florida, 1979. / Vita. Typescript. Includes bibliographical references (leaves 189-199).