Thesis (M.S.)--University of North Carolina at Wilmington, 2002. / Includes bibliographical references (leaves : [49]-50).

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [235]-251).

The Indo-Pacific bottlenose dolphin (Tursiops aduncus) is a common top predator along the KwaZulu-Natal coast. There have been several dietary studies done on this species, most of which have classed this predator as an opportunistic feeder preying on the most abundant prey species in that area. In KwaZulu-Natal (KZN) a dietary study was carried out in 1990, but there have been no followup studies to examine potential changes in diet. A number of bottlenose dolphins get entangled in the shark-nets set off the KZN coast each year. These dolphins provide a valuable source of information about different aspects of the ecology of this population. The aim of this study was to examine the diet of bottlenose dolphins off the KwaZulu-Natal coast with particular emphasis on temporal change in diet composition. The contents of 102 stomachs of bottlenose dolphins (58 females, 44 males) accidentally caught in the shark nets between 1985 and 2010 were analysed, and compared to historical data from dolphins caught between 1975 and 1986. A total of 94 different prey species from 37 families (32 fish families, five cephalopod families) were identified in the stomach contents. Teleosts made up the most important prey group in numbers and weight constituting 84 percent and 67 percent, respectively, while cephalopods made up 15 percent of the number and 30 percent of the weight of the prey items. Multi Dimensional Scaling (MDS) indicated that there is no resource partitioning between males and females, but significant partitioning between juveniles and adults. Six prey species contributed more than 60 percent of the weight of all prey species in the diet. These species are the most important according to their calculated index of relative importance score and are, in order of importance: Sepia sp. (cuttlefish)., Pomadasys olivaceus (piggy), Trachurus delagoa (maasbanker), Scomber japonicus (mackeral), Loligo sp. (squid). and Pagellus bellottii natalensis (pandora or red tjor-tjor). When compared to historic data, no changes in the main prey species has occurred, but the piggy has decreased in importance (1976-1986 percent IRI=45; 2000-2010 percent IRI=22), while the maasbanker has increased (1975-1986, percent RI=4; 2000-2010 percent RI=20). Stable carbon and nitrogen isotope analysis performed on tissue from the teeth of T. aduncus caught in the shark nets between 1970 and 2010 showed that there has been no significant shift in trophic level (δ15N) or in primary prey source (δ13C) over this time. The isotopic signatures of different tissues from an individual were used to create a base line and describe the differences in tissue signatures. Blubber was found to be significantly different from skin and muscle, which were found to be isotopically similar. Skin from remote biopsies can therefore probably be used in place of muscle for isotopic studies of bottlenose dolphins, while caution should be taken when using blubber. Given that T. aduncus is still listed as “data deficient” by the International Union for the Conservation of Nature (IUCN), and the potential for climate change and expanding fisheries to alter the distribution and abundance of their prey species, long term dietary studies such as this are important in order for their effective conservation and management.

In an attempt to correlate genetic data with possible species delineation, this study investigates the presence of chromosomal variants between the North Atlantic bottle nose dolphin, Tursiops truncatus, and the North Pacific bottle nose dolphin, T. gilli. Blood samples were obtained from oceanaria in the United States. Location of capture was correlated with karyotype to compare chromosome morphology with geographic range.

The Eastern Scottish population of bottlenose dolphins (Tursiops truncatus) is the northernmost population of this species. The resident core of this population consists of 120 to 150 different individuals. This small size and its geographical isolation from other populations raises questions about its viability and whether the population has behavioural patterns that differ from those common to other populations of the same species. Microsatellite genetic diversity was low and mitochondrial DNA genetic diversity values were lowest in East Scotland compared to other populations worldwide and to neighbouring populations around UK waters. It has been well documented, from four different field sites worldwide, that male bottlenose dolphins form alliances with preferred male associates. These alliances can last for several years and the males involved show association coefficients similar to those of mothers and calves (0.8-1.0). These alliances appear to be of great importance in obtaining matings for the males. In the Eastern Scottish population males do not form alliances. No evidence of strong associations between individuals of either sex was found and there was no correlation between association and relatedness patterns. I suggest that the isolation and small size of the population together with reduced genetic diversity affects the pressure of kin selection for altruistic behaviours. There is no gain in competing or associating with close relatives for access to mates and it might be more important to avoid inbreeding by dispersing. Although evidence of gene flow between East Scotland and its neighbouring populations was not confirmed with Bayesian clustering analysis, a small set of individuals from Wales were found to be closely related to individuals from the East Coast of Scotland. In general the dynamics found in UK water populations resemble those of the Western North Atlantic with sympatric populations of coastal as well as pelagic individuals.

Two sympatric species of dolphins (Atlantic spotted dolphins, Stenella frontalis and Atlantic bottlenose dolphins, Tursiops truncatus) have been long-term residents to Little Bahama Bank. This study assessed whether there was a change in residence patterns or diurnal foraging depths of bottlenose dolphins following a large emigration event in the resident spotted dolphin community on this sandbank. Photo-identification was used to identify individual bottlenose dolphins and compare pooled years before (2010-2012) and after (2013-2015) the spotted dolphin emigration. The identified community size and overall residency of the bottlenose dolphins remained similar, although two bottlenose dolphins emigrated over deep water to the site spotted dolphins emigrated. Bottlenose dolphins diurnally fed in shallower water but remained in the same geographic foraging locations. Reasons remain unknown for this depth change, but potential changes in the productivity of primary bottlenose dolphin foraging habitats or reduction of spotted dolphins from shallower depths remain possibilities. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

The long-beaked common dolphin, Delphinus capensis (Gray 1828), is one of the most enigmatic predators feeding in the annual sardine run (Sardinops sagax) off the coast of KwaZulu-Natal (KZN), South Africa. In recent years, unpredictable inter-annual variations in the timing, spatial extent and intensity of the sardine run have been documented, possibly resulting in changes in the suite of prey available to the common dolphin during winter. Although the diets of a number of predators during the sardine run have been studied in detail (e.g. sharks and flying seabirds), little is known about the diet of long-beaked common dolphins during this period. Each year, a low number of common dolphins are incidentally caught in the anti-shark nets in the waters of KwaZulu-Natal. These captures provide a valuable source of data on selected aspects of the ecology of the long-beaked common dolphins along the KwaZulu-Natal coastline. The objective of this study was to provide new dietary data for the common dolphins feeding in the waters of KwaZulu-Natal during winter over the period 2000 to 2009, as well as to determine if any dietary changes had taken place since the common dolphin diet was last assessed, over 15 years ago. Stomach contents from 95 common dolphins (55 females, 40 males) caught between 2000 and 2009 were analysed and compared to historical data from dolphins caught between 1974 and 1992. Mesopelagic fish and squid dominated the diet, with 23 fish and 5 squid species represented in adult dolphins. Multidimensional Scaling (MDS) indicated that there was no resource partitioning between adult male and female dolphins. Numerical analyses indicated that there was a shift in the principal prey species consumed by the dolphins over the past decade, particularly during the winter. Prior to 1992, sardine comprised up to 49% of the total stomach contents, while chub mackerel (Scomber japonicus) was the dominant prey item (66% by mass) recorded in the stomach contents over the period 2000 to 2009. The shift in the relative contributions of sardine and mackerel in the diets of the dolphin appeared to correspond to fluctuations in the availability of the two principal prey species. Between 2000 and 2009, the diversity of the dolphins' diets was highest during the sardine run, reflecting the presence of a wide suite of predatory teleosts in the waters of KwaZulu-Natal during the annual sardine run. Conversely, prior to 2000, the diet was dominated by sardine during the peak of the sardine run, whilst diet diversity increased after this period. Apart from sardine and chub mackerel, elf (Pomatomus saltatrix), maasbanker (Trachurus delagoa), strepie (Sarpa salpa) and flying fish (Exocoetid sp.) also formed important components of the diet both prior to 1992, and over the last decade. Blubber thickness was assessed as an indicator of animal condition. No significant change in blubber total weight (R² = 0.0016, N = 185), nor dorsal, lateral or ventral blubber thickness (R² = 0.3146, R² = 0.0003, and R² = 0.0003 respectively, N = 78) was seen over the last 30 years (1970 to 2009). Results of stable isotope analyses conducted on tissue derived from the teeth of D. capensis indicated that there has been no significant shift in the trophic position (δ¹⁵N) and potential prey consumed (δ¹³C) over the corresponding period. These data would suggest that the long-beaked common dolphins along the KwaZulu-Natal coastline can be considered as opportunistic predators generally consuming the most abundant prey species available locally. As common dolphins feed opportunistically, this dietary shift appears to indicate changes in the shoaling characteristics of the most abundant fish prey in KwaZulu-Natal during winter. Given the “Data Deficient” status of the long-beaked common dolphin on the IUCN Red Data List, and the strong climatic forcing of the sardine run, such dietary data have important implications for their conservation in the light of expanding fisheries and climate change.

The population of bottlenose dolphins off the east coast of Scotland has been studied since the late 1980s, initially focused on the inner Moray Firth, where a Special Area of Conservation (SAC) was designated under the EU Habitats Directive. The population has since expanded its distributional range and currently ranges from the Moray Firth to the Firth of Forth. The main aims of this thesis were: (1) to estimate population parameters for this population using a 25 year individual recognition dataset, and (2) to increase knowledge of the distribution and abundance of dolphins in areas outside the SAC, especially to investigate areas of high use in St Andrews Bay. Apparent survival rate for adults and sub–adult dolphins was estimated at 0.946 (SE=0.005) accounting for temporary emigration caused by the population's range expansion. Sex-specific survival was estimated for males (0.951, SE=0.013) and females (0.956, SE=0.011) using multistate models to minimize bias caused by individuals of unknown sex. Using a newly developed approach, fecundity rate was estimated at 0.222 (95% CI=0.218-0.253) from an expected mean inter-birth interval of 4.49 yrs (95% CI=3.94-4.93). Total population size was estimated as ~200 individuals, after accounting for temporary emigration and for heterogeneity in capture probabilities. In St Andrews Bay, an area used regularly in summer by approximately half the estimated population, habitat use modelling identified the entrance to the Firth of Tay and waters around Montrose as high use areas for dolphins, whose presence was influenced by tidal current speed and direction. The results suggest that the conservation and management plan for this small and isolated population of bottlenose dolphins should be reviewed to adapt it to current knowledge, especially regarding the uncertainty around the potential impacts of offshore renewable energy developments off the east coast of Scotland.

The historical range of the Indus River dolphin has declined by 80% since the 19th century and has been fragmented into 17 river sections by construction of irrigation barrages. Dolphin sighting and interview surveys showed that river dolphins persist in six river sections, have been extirpated from ten, and are of unknown status in the remaining section. Logistic regression and survival modelling showed that low dry season river discharge was the primary factor responsible for the Indus dolphins range decline. Abundance of the three largest Indus dolphin subpopulations was estimated using tandem vessel-based direct counts, corrected for missed animals using conditional likelihood capture-recapture models. The entire subspecies was estimated to number between 1550-1750 in 2006. Dolphin encounter rates within the Guddu-Sukkur subpopulation (10.35/km) were the highest reported for any river dolphin and direct counts suggest that this subpopulation may have been increasing in abundance since the 1970s when hunting was banned. The dry season habitat selection of Indus dolphins was explored using Generalised Linear Models of dolphin distribution and abundance in relation to river geomorphology, and channel geometry in cross-section. Channel cross-sectional area was shown to be the most important factor determining dolphin presence. Indus dolphins avoided channels with small cross-sectional area <700m2, presumably due to the risk of entrapment and reduced foraging opportunities. The phylogenetics of Indus and Ganges River dolphins was explored using Mitochondrial control region sequences. Genetic diversity was low, and all 20 Indus River dolphin samples were identical. There were no haplotypes shared by Indus and Ganges River dolphins, phylogenetic trees demonstrated reciprocal monophyletic separation and Bayesian modelling suggested that the two dolphin populations diverged approximately 0.66 million years ago. Declining river flows threaten Indus dolphins especially at the upstream end of their range, and it is important to determine how much water is required to sustain a dolphin population through the dry season. Fisheries interactions are an increasing problem that will be best addressed through localised, community-based conservation activities.

The purposes of this dissertation were to identify complex social-cognitive behaviors in a population of wild Atlantic spotted dolphins (Stenella frontalis) using long-term video archives and identify developmental trends in those behaviors. Chapter One analyzed calf behavior during foraging events involving maternal teaching in order to identify mechanisms for sharing information between mother and calf... The calves' behavior was affected by the referencing cues, supporting the presence of joint attention and true teaching behavior....Chapter Two observed the altered benthic foraging behavior of juvenile play groups, in which juveniles took turns chasing the fish and using referencing gestures to reference the position of the fish to other individuals during the chase, despite the ability of these young, independent dolphins to catch fish much more quickly and efficiently alson... The third chapter analyzed social object play in which dolphins passed pieces of seaweed between individuals. The data clarified developmental trends in the play, and suggested social-cognitive abilities needed for participation. / by Courtney Elizabeth Bender. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.