University of Oregon theses, Dept. of Biology, Ph. D., 1973. A print copy of this title is available from University of Oregon's Oregon Institute of Marine Biology library and the Science library, under the call number: QL 737.P63 M3

Thesis (M.S.)--University of British Columbia, 1997. / Includes bibliographical references (leaves 70-84).

The Australian sea lion, Neophoca cinerea, is Australia?s only endemic pinniped, and one of the rarest sea lions in the world. This species suffered localised extinction events, and a probable population decline during the commercial sealing era of the 18th to 20th centuries. This species also has a unique reproductive cycle and breeding system compared with all other pinnipeds. Unlike the usual annual, synchronous cycle, this species has a 17.5 month breeding cycle which is asynchronous across its range. Small groups of proximate colonies appear to breed synchronously, but otherwise the timing appears randomly distributed. It was proposed that this system is endogenously controlled and maintained by exclusive female natal site fidelity (Gales et al. 1994). This would have a discernible impact on the population genetic structure, and would be directly applicable to conservation management practices. Investigation of population genetic structure of the Australian sea lion using mtDNA and microsatellite markers revealed a highly subdivided population that showed strong patterns of sex-biased dispersal, and strong regional divisions. The level of female natal site fidelity was extreme, resulting in very high levels of genetic differentiation, unparalleled in other marine mammal populations. Significant divisions existed across both macro and micro geographic scales, with fixed differences occurring between colonies separated by as little as 20 kilometres. Strong phylogeographic patterning suggested that divisions between populations are of some antiquity. High levels of fixation in mtDNA markers among the many small colonies in Western Australia was attributed to the high rate of genetic drift in small populations, especially for these markers. Genetic subdivison, as measured by microsatellite markers, revealed a malebiased dispersal pattern. Levels of male dispersal were sufficient in overcoming the female natal site fidelity and rendering small groups of colonies effectively panmictic. However, the range of male dispersal was limited to approximately 200 kilometres and resulted in a regional population structure best defined by geographic distance. This level of subdivision was perhaps greater than expected given the dispersal capabilities of this species, and suggested that some behavioural processes may limit dispersal. Historical processes of extinction and colonisation are thought to have had a strong influence on the current pattern of population subdivision as well.

Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of environmental vibrotactile cues. Pinnipeds possess the largest and most highly innervated vibrissae among mammals and their vibrissae demonstrate a diversity of shapes and likely mechanical properties. These two characteristics are important for vibrotactile sensory perception. Vibrissae of most phocid seals exhibit a beaded morphology with repeated sequences of crests and troughs along their length. I comparatively characterized differences in vibrissae morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods to test the hypothesis that vibrissal morphologies are species-specific manipulations of a common pattern. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to taxon based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. At least three separate morphologies were identified since phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Another important characteristic that influences the transduction of vibrotactile information to the mechanoreceptors in the follicle-sinus complex is the materials properties of the vibrissae. Vibrissae were modeled as cantilever beams and flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces flexural stiffness and that vibrissae are anisotropic (orientations differ in EI). Species were significantly different and smooth vibrissae were generally stiffer than beaded vibrissae. Beaded vibrissae decrease vibrations in flow, which, combined with lower flexural stiffness values, may enhance detection of small changes in flow from swimming prey. The anterior plane of the vibrissae is likely the most biologically significant in tracking hydrodynamic trails but had lower flexural stiffness values than the dorsoventral orientation. There is likely a complex interaction between shape and mechanical properties in pinniped vibrissae but the ecological and functional implications are currently unknown.

Thesis (Ph. D.)--University of Adelaide, 1984. / Includes bibliographical references (leaves 193-224).

Thesis (M.S.)--University of California, Santa Cruz, 1984. / Typescript. Includes bibliographical references (leaves 35-37).

New Zealand sea lion (Phocarctos hookeri) is a pinniped endemic to New Zealand and is among the rarest of sea lion species. New Zealand sea lions are incidentally caught in the trawl fishery for squid around the Auckland Islands, and a sea lion catch-limit or Fishing Related Mortality Limit (FRML) is used to manage this interaction. Since 2003 such limits have been calculated using an age-structured Bayesian population model. One problem with this approach is that several key demographic parameters have had to be assumed, or are based on very few data. Archaeological and other historical records demonstrate that New Zealand sea lions were substantially more widespread before the arrival of humans to New Zealand than they are today (Chapter 2 published as Childerhouse & Gales 1998). The present population size is clearly reduced, with subsistence and commercial hunting the most likely cause of historical changes in distribution and abundance. Campbell Island, the only significant breeding site outside the Auckland Islands, was thoroughly surveyed for New Zealand sea lions for the first time in 2003. An estimated 385 pups were born there, comprising 13% of the total pup production for the species for 2003 (Chapter 3 published as Childerhouse et al. 2005). This thesis provides the first robust estimates of several demographic parameters for New Zealand sea lions. These data were gained via the capture, tagging and ageing of 865 individual females, which had come ashore to pup between 1999 and 2001. This research was underpinned by the development of a novel and robust ageing technique for live New Zealand sea lions (Chapter 5 published as Childerhouse et al. 2004). Chapters 6, 7 and 8 used analyses of the age structure of these females, and of subsequent resightings of them, and of known-age females between 1998 and 2005, provided the first estimates of individual growth, mean reproductive rate (0.67, SE = 0.01), mean adult survival (0.81, SE = 0.04), and maximum age (28 years) for females. These data show that New Zealand sea lions are among the slowest growing, slowest reproducing, and longest lived sea lion species. Significant differences in the age structure of the two largest breeding colonies highlight flawed assumptions of the current management approach. The application of this new demographic information has the potential to significantly alter the existing management advice relating to the setting of FRMLs and the impact of the squid fishery on the New Zealand sea lion population. Taken alone, these results suggest a dim outlook for an already threatened species. In the context that pup production is in significant decline (e.g. 32% since 1998 Chilvers et al. 2007), the species� foraging environment is thought to be marginal (Costa & Gales 2000), and that resource competition may also be impacting on the population (Chapter 4 published as Childerhouse et al. 2001a), the picture darkens further. Taken as a whole, these data suggest that current management is insufficient to ensure population stasis, let alone meet the Government�s statutory goal of recovery.

Bibliography: leaves 193-224.

The ability of animals to contend with unpredictable seasonal shifts in quality and quantity of prey has implications for the conservation of wildlife. Steller sea lions(Eumetopias jubatus) were subjected to different quantities and qualities of food to determine what physiological and endocrine responses would occur and whether they differed between season (summer and winter) or diet (high-lipid Pacific herring Clupeapallasi vs. low-lipid Walleye Pollock Theragra chalcogramma). Eight females were divided among two groups. One (Group H) were fed herring for 28 days (baseline), then received a reduced caloric intake for a subsequent 28 days (restriction) to induce a 15%loss of body mass. The second (Group P) were also fed herring during the baseline followed by a reduced isocaloric diet of pollock during the restriction. Both groups subsequently returned to their baseline intake of herring for a 28-day controlled re-feeding. The two groups of sea lions lost identical mass during restrictions independent of species eaten, but did differ in the type of internal energy reserve (protein vs. lipids) they predominantly used. Group H lost significantly more lipids and less lean mass than Group P in both seasons. In summer, Group H also increased activity levels and decreased thermoregulation capacity to optimize energy allocation. No such changes were observed for Group P whose capacity to adjust to the reduced caloric intake seemed to have been blocked by the pollock diet. During winter, the sea lions spared energy allocated to activity (especially Group H) and preserved thermoregulation capacity. Changes in body mass was negatively related to free cortisol and positively related to IGF-1 in winter, but only IGF-1 was related to changes in mass in summer when lean mass regulation seemed more important. Levels of IGF-1 were associated with changes in protein metabolism in both seasons for both groups, but changes in body condition were never explained by the measured metabolites or hormones. The capacity to compensate for mass loss was seasonally dependent with sea lions displaying compensatory growth (by restoring lipid stores) in winter but not in summer. Summer appears to be a more difficult season for sea lions to recover from mild nutritional stress. These physiological findings can be used to refine bioenergetic models needed for the conservation of Steller sea lion populations.

The ability of animals to contend with unpredictable seasonal shifts in quality and quantity of prey has implications for the conservation of wildlife. Steller sea lions(Eumetopias jubatus) were subjected to different quantities and qualities of food to determine what physiological and endocrine responses would occur and whether they differed between season (summer and winter) or diet (high-lipid Pacific herring Clupeapallasi vs. low-lipid Walleye Pollock Theragra chalcogramma). Eight females were divided among two groups. One (Group H) were fed herring for 28 days (baseline), then received a reduced caloric intake for a subsequent 28 days (restriction) to induce a 15%loss of body mass. The second (Group P) were also fed herring during the baseline followed by a reduced isocaloric diet of pollock during the restriction. Both groups subsequently returned to their baseline intake of herring for a 28-day controlled re-feeding. The two groups of sea lions lost identical mass during restrictions independent of species eaten, but did differ in the type of internal energy reserve (protein vs. lipids) they predominantly used. Group H lost significantly more lipids and less lean mass than Group P in both seasons. In summer, Group H also increased activity levels and decreased thermoregulation capacity to optimize energy allocation. No such changes were observed for Group P whose capacity to adjust to the reduced caloric intake seemed to have been blocked by the pollock diet. During winter, the sea lions spared energy allocated to activity (especially Group H) and preserved thermoregulation capacity. Changes in body mass was negatively related to free cortisol and positively related to IGF-1 in winter, but only IGF-1 was related to changes in mass in summer when lean mass regulation seemed more important. Levels of IGF-1 were associated with changes in protein metabolism in both seasons for both groups, but changes in body condition were never explained by the measured metabolites or hormones. The capacity to compensate for mass loss was seasonally dependent with sea lions displaying compensatory growth (by restoring lipid stores) in winter but not in summer. Summer appears to be a more difficult season for sea lions to recover from mild nutritional stress. These physiological findings can be used to refine bioenergetic models needed for the conservation of Steller sea lion populations.