Thesis (M. Sc.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, June 2006.

Aspects of morphological and physiological condition of captive and net-caught dolphins were studied with respect to age, diet, reproduction and seasonal changes in environmental factors. These investigations aimed to provide base-line data on marine mammal physiological and morphological condition indices and to expand the knowledge of condition assessment of small cetaceans. By examining the interactive nature of animal condition and growth, diet and the environment, the study investigated the potential usefulness of animal condition indices to assess and monitor habitat quality. Base-line values for haematological and blood chemistry parameters were established for five captive bottlenose dolphins (Tursiops truncatus), using monthly blood samples, collected between 1992 and 1995, and corresponding measures of body weight and blubber thickness; feeding, dietary energy intake, water temperature and behavioural and medical records. Curves of best fit were used to interpret trends between leukocytic, haematological and blood chemistry parameters and morphology, diet and water temperature. WBC's and WBC differential cell types were related more distinctly to clinical changes in health, than to condition. RBC, HB and PCV were useful as short-term indicators of nutritional condition, with enhanced haematological status associated with greater food intake and improved diet quality. Weight was a more effective long-term indicator of nutritional status. The importance of blubber thickness measurements as a morphological index of condition was reinforced, with relationships between blubber thickness and haematology highlighting interactions between morphological and physiological condition. The complex interactions between haematology, diet, temperature and weight emphasised the need to account for all influential factors when considering haematological condition. The blood chemistry parameters of serum creatinine, BUN, BUN:creatinine and serum albumin provided the best indication of nutritional condition and diet quality in captive dolphins. Creatinine and BUN:creatinine also reflected changes in morphological condition. Reduced ALP was associated with nutritional stress but was more effectively used as an indication of metabolism and growth activity. LDH and CPK were highly variable and fluctuated with changing activity levels, limiting their use as condition indices. Serum sodium was an important indication of diet quality and hydration status. Many of these parameters effectively illustrated that physiological condition is compromised outside of the thermoneutral zone of the species. Bottlenose and common (Delphinus delphis) dolphins, incidentally caught in shark nets, were used to investigate the condition of free-ranging dolphins. Blood samples, taken as soon as possible after capture from drowned animals, were used to analyse physiological parameters. Dissections provided morphological data. Age and dietary status were assessed using growth layer groups in teeth and stomach content analyses, respectively. Morphological measures of net-caught dolphins reflected important interactions with diet, water temperature and reproductive status. Weight, girth and blubber thickness were valuable indicators of condition, although blubber thickness and proportional blubber weight were the best indicators of nutritional status. Condition of net-caught dolphins was difficult to assess in terms of leukocytic and haematological parameters. Stress- and post-mortem-associated changes, and variable data, reduced the usefulness of some parameters. WBC counts reflected on immunological status and served to emphasise changes in health, which may lead to deterioration in condition. WBC's showed potential as indicators of habitat quality, in terms of parasite load and/or pollution. Interactions between RBC, HB, PCV, MCV and dietary, morphological and environmental factors proved valuable in the short-term. Several haematological parameters were related to morphological condition, with weight, girth and blubber thickness, showing potential as non-invasive predictors of haematological status. Relationships between haematology and water temperature implied that dolphins have physiological and environmental "zones of comfort", within which condition is optimised. LDH and CPK were elevated by capture stress and post-mortem changes. Serum sodium and plasma glucose were good indicators of short-term nutritional status, but were altered by stress, which reduced their usefulness as condition indicators. BUN, albumin, globulin, albumin:globulin, total cholesterol and triglycerides appeared to be little affected by these changes and are potentially valuable indicators of condition in net-caught and/or free-ranging dolphins, particularly with respect to nutritional condition, and associated changes in morphology. Although data were limited, these parameters show the greatest potential as physiological indicators of animal condition and environmental health. The limitations of this study are recognised, however, results highlight the feasibility of using net-caught specimens to monitor the condition of free-ranging marine mammals, and the marine habitat as a whole. Relationships established in this study will be used to elucidate further on the interactive nature of marine mammal condition and aid in the development of a non-invasive condition assessment technique.

The biology of bottlenose dolphins from the east coast of southern Africa is investigated. Births occur predominantly in summer, after a one year gestation period. Calves are born at a length of approximately 103 cm and a mass of nearly 14 kg. Neonates are closely attended by the mother, she determines the calf's respiration rate and behaviour as it swims in a negative pressure vortex high on her flank. The initial weeks are marked by the calf's acquisition of swimming skills and its ability to regulate its own respiration rate. Although the calf takes solid food between six months and one year, suckling may continue for as much as three years. Initial growth is rapid but slows with the approach to puberty. Females reach sexual maturity at about ten years of age and may undergo a series of rapid ovulations before fertilisation occurs. Subsequently, the mean ovulation rate indicates a three year calving interval. Males show a mass growth spurt at the onset of puberty, between 10 and 12 years, and reach sexual maturity between 12 and 15 years of age. In both sexes, physical maturity and asymptotic size are reached at about 15 years and maximum life-span is in excess of 40 years. Although a wide variety of fish and cephalopods are taken, the fishes Pomadasys olivaceum, Scomber japonicus, Pagellus bellotti, Trachurus delagoae, and the cephalopods Sepia officinalis and Loligo sp. contribute some 60 % by mass of all prey taken. Different sex and maturity classes of dolphins consume differing sizes and species of prey, implying a partitioning of food resources within the group. Comparisons of stomach volumes with estimates of prey mass and nutritional requirements suggest that calves and lactating females may need to feed more often than other sex and maturity classes. Examination of shark stomachs indicates that shark predation may be an important component of dolphin natural mortality. Four species of shark, the Zambesi (Carcharhinus leucas), the tiger (Galeocerdo cuvien), the great white (Carcharodon carcharias) and the dusky shark (Carcharhinus obscurus) are implicated as dolphin predators. Estimates from the number of these four species caught annually and the frequency of occurrence of dolphin flukes and vertebrae in their stomachs suggest that a minimumof 20 bottle nosed dolphins or 2.2 % of the estimated population in southern Natal coastal waters are killed each year by sharks. Some 32 bottlenose dolphins, about 4 % of the estimated population, are captured in shark nets annually. Calves of two years or less constitute nearly 45 % of the catch, while lactating females make up a further 15 %. An analysis of biological, environmental and physiographic factors associated with each capture, suggest that feeding and probably prey movement and distribution are directly associated with capture. PCB, t-DDT and dieldrin concentrations in the blubber of male bottlenose dolphins increase with age and reach levels that may impair testosterone production. In females, there is an 80 % decline in residue concentrations after the first or second ovulation. Evidence presented suggests that first born calves receive possibly lethal doses of residues within two months of birth. Residue concentrations in dolphins from different geographical areas varied significantly, implying a degree of isolation of sections of the population. Investigation of reproductive parameters indicates that mortality of bottlenose dolphins off Natal probably equals or exceeds the replacement rate. The necessity for and requirements of further research on the natural history of bottlenose dolphins off the east coast of southern Africa are summarised. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.

Part one of this thesis examined the tropical oceanic cetacean community occurring between Togo and Angola (6°N-11°S latitude).  Twenty-two cetacean species were recorded during 5905.3 hr of dedicated survey effort from platforms of opportunity between 2004 and 2009.  Sperm whales (<i>Physeter macrocephalus</i>) and humpback whales (<i>Megaptera novaeangliae</i>) were the most frequently-sighted species, and exhibited significant differences in occurrence related to water depth and survey month.  Five species inhabited both neritic and oceanic waters, while the remainder were exclusively oceanic.  The habitat preferences and niches (based on depth, seabed slope, sea surface temperature (SST) and frontal strength) of eight species were examined using classification trees and a principle component analysis.  Water depth and SST appeared to be the primary variables (of those examined) explaining the presence of most species.  Part two of the thesis was a study of the Atlantic humpback dolphin (<i>Sousa teuszii</i>), a species endemic to nearshore eastern tropical Atlantic (ETA) waters.  A total of 1,626.8 km of boat- and vehicle-based effort in Namibe Province during 2008, produced 52 <i>S. teuszii </i>sightings.  Further sightings were recorded during 53.7 hr of shore-effort at Flamingos (<i>n</i>=6) and opportunistically (<i>n</i>=13). Ten individuals were photo-identified. Multiple resightings (and an absence of unmarked animals) indicated low abundance, high site fidelity and year-round occurrence.  <i>Sousa teuszii </i>produced simple (85% had a single inflection point) whistles in the 2.5-23.4 kHz fundamental frequency range and broadband click trains with repetition rates varying from 5.8-250.8 clicks/s.  The implications of the findings for the future monitoring and conservation of cetaceans in the ETA are discussed.

I examined summer home range use of Altantic spotted dolphins in the Bahamas from 1991-2004. Home ranges for 86 dolphins using the 95% Fixed Kernel Density (FKD) estimator averages 62.o km2+=22.96 km2 and ranged from 24.8 km2 to 148.4 km2. Older animals and males had the largest ranges. Home range size did not vary with female reproductive status. core areas were defined by the 50% FKD contour and averaged 10.32 km2 +=5.47 km2. Habitat use was different between reproductive states for females. Non-reproductively active (NRA) females used deeped habitat. Behavioral use of the home range varied spatially. The core area was an important foraging area for males and reproductively active females. NRA females foraged more outside their core area compared to the core area. / by Bethany Augliere. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

No description available.

Male bottlenose dolphins (Tursiops sp.) in Shark Bay, WA, form several levels of alliances. Determining the relationship between paternity, relatedness and alliance membership is crucial in seeking evolutionary adaptive explanations for alliance formation. Previous behavioural data have revealed a social system whose complexity is unparalleled outside humans. Pairs or trios of male dolphins cooperate as stable first-order (1? alliances to sequester and control reproductive females. Two 1?alliances sometimes cooperate as small second-order (2? alliances to attack other 1?alliances or defend against attacks. Some males choose a different strategy by forming large superalliances of approximately fourteen individuals to attack 1?and 2?alliances. Kinship appears to play a role in the structuring of male alliances, but its importance differs with the alliance type. Relatedness analyses showed that on average, males in 1?and 2?alliances are strongly related, while members of the superalliance are not. Further, the strength of the association of partners within the superalliance was not correlated with their genetic relatedness. Thus, within one sex, it appears that there may be more than one simultaneous mode of group formation and its evolution. There was also an association between alliance behaviour and reproductive success as predicted by some theories of group formation. I assigned nine paternities to six out of 107 mature males. Males with alliance partners were significantly more successful in fathering offspring than males without partners. Compared to non-allied males, the chance of obtaining a paternity was significantly higher for members of 1?alliances, and reproductive success was significantly skewed among 1?alliance members. Assessment of kinship and relatedness required a number of technical developments and some preliminary data. I first refined a biopsy system in order to obtain tissue samples from free-ranging dolphins with minimum behavioural effects irrespective of age-group or gender. Then I carried out population genetics analyses, which demonstrated that there was only weak population structure within Shark Bay. Microsatellites showed a weak pattern of isolation by distance, and eight haplotypes of the mitochondrial DNA control region suggested weak female philopatry. The high number of migrants between locations allowed all samples from East Shark Bay to be pooled for subsequent analyses.

Recent advances in technology permitted the first simultaneous digital recording of intranarial pressure and on-axis acoustic data from bottlenose dolphins during a biosonar target recognition task. Analysis of pressurization events in the intranarial space quantifies and supports earlier work, confirming that intranarial pressure is increased when whistle vocalizations are emitted. The results show complex relationships between various properties of the biosonar click to the intranarial pressure difference at the time it was generated. The intranarial pressure that drives the production of clicks is not the primary determinant of many of the acoustic properties of those clicks. A simple piston-cylinder physical model coupled with a sound production model of clicks produced at the monkey-lips/dorsal bursae complex yields an estimate of mechanical work for individual pressurization events. Individual pressurization events are typically associated with a single click train. Mechanical work for an average pressurization event is estimated at 10 Joules.

The Risso’s dolphin (Grampus griseus G. Cuvier, 1812), one of the largest in the family Delphinidae, with groups ranging from a couple to over 80 individuals, can be found in temperate and tropical regions worldwide. They prefer waters 400 - 1000 meters deep and proximity of continental slopes. Their social structure was suggested to be based on age and sex, with strong bonds between adult males and between adult females. In Chile, prior to my research, there is only one publication on Risso’s dolphins; according to this report, they occur continuously along the Chilean coast. La Herradura, a small and shallow bay, is located on the central-north coast of Chile, facing the Pacific Ocean. During a one year of study (April 2011 to April 2012), daily scans of the bay were conducted, covering the interior of La Herradura, and photo-identification boat surveys were undertaken within and outside the bay. In the course of this 1-year study, a total of 13 encounters were recorded outside the bay and 16 encounters inside the bay. The occurrence of Risso’s dolphin outside the bay did not show any clear pattern across the year. Dolphin groups encountered outside had a mean group size of 20 individuals (SD=19.5) and a median of 16. Of these groups, 38.5% had calves and the main behavior showed by the groups was travelling and foraging. Inside La Herradura bay, the groups of dolphins were seen primarily during the morning (8:00-12:00); this pattern was consistent across the study period. The mean group size was 63 individuals (SD=45.3) and a median of 46 individuals. The 87.5% of these groups had calves among them and the main behavior observed was milling. A total of 747 individuals were photographically identified across 44 encounters and were used for mark-recapture analyses. Supplementary data, collected opportunistically between 2007 and 2010, provided by Mr. Oliver Yates, were included to increase the robustness of the analyses. Most of the individuals were sighted just once or twice during the 5-year period (2007-2012). The estimated size of the population generated by POPAN parametrization in program MARK was 3468 individuals (SE=188.5; 95% CI 3144 to 3889). Overall, Risso’s dolphin in the La Herradura area had very low site fidelity and the associations among individuals were generally weak (mean HWI=0.17 ±±SD=0.06). However, HWI picked at 0.2-0.3 and the results of principal coordinate analyses (5 clusters, modularity= 0.24) seem to indicate a grouping pattern that, although not rigorously tested due to the limitation of the sample size, might be indicative of preferential cluster-type associations within an overall fluid society. Overall, in Coquimbo, Risso’s dolphin groups with calves seemed to use the La Herradura Bay as a resting site during the morning, probably after having spent the night foraging. The animals display typical fission-fusion dynamics. However, it is possible that the dolphins form a substantially more structured social grouping, which could only be tested with a longer study period and larger sample size. / published_or_final_version / Biological Sciences / Master / Master of Philosophy