Dissertations / Theses: 'Sea lions'

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Hui, Tabitha Cheng Yee. "Steller sea lions and fisheries : competition at sea?" Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/32588.

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A leading hypothesis to explain the decline of Steller sea lions (Eumetopias jubatus) in western Alaska is the reduction of prey abundance or change in prey distributions caused by commercial fisheries. We sought to improve on past studies that attempted to assess competition between sea lions and fisheries by estimating the local amounts of prey accessible to sea lions. We explored the relationships between sea lion population trends, fishery catches and the prey biomass accessible to sea lions around 33 rookeries from 2000-2008. We focused on three commercially important species that dominate the sea lion diet: walleye pollock, Pacific cod and Atka mackerel. We estimated available prey biomass by removing fishery catches from predicted prey biomass distributions in the Aleutian Islands, Bering Sea and Gulf of Alaska; and modelled the likelihood of sea lions foraging at different distances from rookeries (accessibility) using satellite telemetry locations of tracked animals. We combined this accessibility model with the prey distributions to estimate the prey biomass accessible to sea lions by rookery. For each rookery, we compared sea lion population change to accessible prey biomass (estimated using our accessibility model and also within 10, 20 and 50 km of each rookery). Of the 304 statistical models we constructed to compare accessible prey biomass and catch to sea lion population trends, only three relationships were significant. These three suggest that sea lion population change rates increased (became less negative) with increasing accessible pollock biomass in the Aleutian Islands and with cod biomass in the Gulf of Alaska. No relationships were found between sea lion population trends and Atka mackerel biomass. Given that the majority of the relationships we explored were insignificant, it seems unlikely that the availability of pollock, cod or Atka mackerel was limiting sea lion populations in the 2000s. Sea lion population trends appeared to be affected by some unknown factor associated with regional differences. Removing fish catches or adding catch to our predicted distributions of groundfish abundances had no measurable effect on sea lion population trends. These observations suggest that sea lion populations were largely unaffected by fishery removals during this period.

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2

Childerhouse, Simon, and n/a. "Conservation biology of New Zealand sea lions (Phocarctos hookeri)." University of Otago. Department of Marine Science, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080213.144055.

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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.

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3

Campbell, Richard. "Demography and population genetic structure of the Australian sea lion, neophoca cinerea." University of Western Australia. School of Animal Biology, 2003. http://theses.library.uwa.edu.au/adt-WU2005.0058.

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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.

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Lee, Kessina. "Stranding Mortality Patterns in California Sea Lions and Steller Sea Lions in Oregon and Southern Washington, 2006 to 2014." Thesis, Portland State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10135722.

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As changing ocean conditions lead to declining fish stocks and movement of forage fish, sea lions on the Oregon coast are subject to the pressures of declining prey availability and increasing conflicts with commercial and recreational fisheries. An analysis of strandings of California sea lions, _{Zalophus californianus,} and Steller sea lions, Eumetopias jubatus, from 2006 to 2014, included cause of death, changing ocean conditions, and anthropogenic activity. Causes of death included disease, injury, and human interaction, such as gunshot wounds, fisheries net entanglements and boat strikes.

Oregon and Washington strandings of California sea lions are primarily adult and subadult males that migrate north from California rookeries, while Steller sea lions are year-round residents and strandings are comprised of males and females of all ages. While the California sea lion population is currently at or near carrying capacity, the Eastern Pacific population of Steller sea lions was designated as Threatened under the Endangered Species Act until October 2013. Understanding impacts to these two pinniped species is vital to implementing effective management and conservation policies.

Oregon and southern Washington strandings of California sea lions and Steller sea lions from 2006 to 2014 were analyzed spatially using the geographic information system (GIS), and temporally to identify possible correlations with prey availability and human interaction. Strandings were found to follow seasonal patterns from year to year: Steller sea lion strandings were highest from May to July, California sea lions peaked in September, October, and November. There was a correlation between significantly high numbers of strandings and the three largest commercial fisheries in Oregon: Chinook salmon, Coho salmon, and Dungeness crab.

This analysis provides a format for continuing to monitor primary ecological and anthropogenic drivers of pinniped mortality in Oregon and southern Washington.

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Chumbley, Kathryn. "Prey biomass abundance, distribution, and availability to the endangered stellar sea lion (Eumetopias jubatus) population at Ugamak Island, Alaska, 1995-99." Online pdf file accessible through the World Wide Web, 2007. http://archives.evergreen.edu/masterstheses/Accession86-10MES/Chumbley_K%20MESThesis%202007.pdf.

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6

Hoopes, Lisa Ann. "Metabolic and thermoregulatory capabilities of juvenile steller sea lions, Eumetopias jubatus." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1390.

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7

Schrader, Wendy Jane. "Foraging behavior of juvenile steller sea lions in the Gulf of Alaska." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5922.

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Relating the behavior of predators to prey density is an important aspect of foraging theory. Changes in prey accessibility may have contributed to a greater-than 80% decline in Steller sea lions (Eumetopias jubatus) throughout the western portion of their range during the last 30 years. A new method was developed for inferring prey accessibility to juveniles of this otariid, from observable features of diving and ranging behavior. Seventeen juveniles (9F, 8M) were monitored in multiple seasons and locations in the Gulf of Alaska via satellite telemetry. Twelve of the 17 had experienced 1-3 months of temporary captivity. Effects of temporary captivity on endurance, habitat use and development of diving and ranging behavior were tested. Diving and ranging patterns of previously captive juveniles were consistent with data reported for freeranging juveniles. Development in mean dive depth and duration after release was likely due to increased foraging. "Focus in time spent at depth" was tested as a proxy for prey accessibility using predictions based on foraging theory. 'Focus...' was defined as vertical concentration in dive distribution and was calculated by comparing the observed time spent at depth with an expected distribution. There was significantly more focus in summer than winter, and more focus at depth (>62 m) in winter. Focus at depth was significantly greater during midday for juveniles monitored in winter. Significant negative correlation between maximum focus and trip duration provided the best indication that focus may be related to prey accessibility. Short trips had significantly greater maximum focus than long trips, using a matched-pairs approach. Analysis of focus in time-at-depth data can elucidate small scale interactions between juvenile otariids and their prey. This new method of measuring the dive behavior of otariids can be applied to individual foraging trips and holds promise as a proxy for assessing seasonal, annual and developmental changes in individual prey accessibility.

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8

Allen, Pamela Claire. "Seasonal oscillations in the mass and food intake of Steller sea lions." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/7289.

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Morphometric measurements and daily feeding records of 62 captive Steller sea lions (Eumetopias jubatus) were analyzed to provide information about seasonal growth and food consumption that has been impossible to collect from wild animals. Data from nursing pups, intact and castrated males, and pregnant, lactating and non-reproductive females were also used to determine differences in rates of sexual maturity, and the effects that climate, sexual maturity, castration and reproduction have on growth and food intake. Data were fit with seasonal and annual growth models, and showed that males achieved larger body sizes than females by undergoing a growth spurt during puberty and by extending their growth throughout adulthood. Annual increases in the length and mass of females slowed significantly following sexual maturity. Males and females both experienced seasonal oscillations in body mass, but the seasonal fluctuation in male mass peaked later (April) and was far more dramatic than that of females. The mass of lactating and non-reproductive females peaked in early spring (March), while increases in the mass of pregnant females paralleled fetal growth, reaching a maximum before parturition. Changes in mass did not parallel changes in consumption. Fish intake by males and females peaked during winter and bottomed during spring, while seasonal changes in body mass reached their high and low 3 to 4 months later than food intake. Pregnant and non-reproductive females differed little in the amount of prey they consumed, unlike lactating females that significantly increased their consumption during summer and winter. The differences between females highlight the relatively low additional energetic requirements of pregnancy and the high costs of lactation. Differences between neutered and intact males further suggest that testosterone affected overall male growth, but had smaller effects on seasonal oscillations in mass and did not affect food intake. The reproductive cycle and thermoregulatory requirements appeared to drive seasonal changes in body mass and food intake of male and female Steller sea lions but at different time scales. Our findings also indicate that mass is not a simple reflection of food intake, which has important implications for future nutritional research and bioenergetic modeling of wild pinnipeds.

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Michael, Sarah. "Causes and mitigation of pup mortality in New Zealand sea lions (Phocarctos hookeri)." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28192.

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New Zealand (NZ) sea lions (Phocarctos hookeri) are an endangered and endemic species to NZ. Following historic extirpation from their original range around mainland NZ, now nearly all breeding occurs at islands in the NZ sub-Antarctic between latitudes 50-53°S. Following a period of decline in pup production at the Auckland Islands for a decade to near threshold low numbers in 2015, around half of that at the apparent peak, the New Zealand Sea Lion Threat Management Plan was developed with several streams aiming to guide research and active management to improve the species’ population trajectory. NZ sea lions at the most studied site, Enderby Island in the Auckland Islands have been subject to several disease events, with ongoing impacts on pups due to a now endemic hypervirulent (HV) strain of Klebsiella pneumoniae following epizootic emergence at the site in 2001-02. Pup mortality due to HV K. pneumoniae has been modelled as a primary perceived threat to NZ sea lions that if mitigated, could aid in increasing population growth rate. As a result, this thesis aimed to determine the prevalence of all causes of pup mortality, identify important contributing risk factors and investigate potential avenues of active management by conducting a case-control study and a prospective cohort study over two austral summer field seasons (2016-18) at Enderby Island. A nested randomised controlled treatment trial with the anthelmintic ivermectin was run concurrently to assess the contribution of hookworm (Uncinaria spp.) to mortality. Evidence for feasible management options based on demonstrated risk factors for pup mortality is developed and explored.

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Milette, Linda Leontine. "Behaviour of lactating Steller sea lions (Eumetopias jubatus) during the breeding season : a comparison between a declining and stable population in Alaska /." PURL, 1999. http://www.arlis.org/docs/vol1/61127341.pdf.

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Baker, Alyson Renee. "Variation of mitochondrial control region sequences of Steller sea lions: the three-stock hypothesis." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/225.

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Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.

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Orsini, Jean-Paul. "Human impacts on Australian sea lions, Neophoca cinerea, hauled out on Carnac Island (Perth, Western Australia): implications for wildlife and tourism management." Thesis, Orsini, Jean-Paul (2004) Human impacts on Australian sea lions, Neophoca cinerea, hauled out on Carnac Island (Perth, Western Australia): implications for wildlife and tourism management. Masters by Research thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/238/.

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Over the last 15 years, pinniped tourism has experienced a rapid growth in the Southern Hemisphere, and particularly in Australia and New Zealand where at least four sites attract more than 100,000 visitors per year. Tourism focused on the Australian sea lion (Neophoca cinerea), a protected species endemic to Australia, occurs in at least nine sites in South Australia and Western Australia. Australian sea lions haul out on several offshore islands in the Perth region. Carnac Island Nature Reserve is one of the main sites where people can view sea lions near Perth, either during recreational activities or on commercial tours. This study sought: (1) to investigate the potential impact of human visitors on Australian sea lions hauled out on Carnac Island, (2) to consider implications of the results for the management of Carnac Island Nature Reserve, and (3) to examine under which conditions tourism and recreation around sea lions can be sustained in the long term. Sea lion numbers, rate of return to the site, behavioural response to human presence and incidents of disturbances of sea lions by visitors were recorded over a period of four months on Carnac Island. A survey of 207 visitors was also carried out. Findings indicated that there were two main types of human impacts on the sea lions: * A specific state of sea lion vigilance induced by low level, but ongoing, repetitive disturbances from human presence, sustained at various approach distances ranging to more than 15 m, vigilance that is different from the behaviour profile observed in the absence of human disturbance, * Impacts resulting from incidental direct disturbances of sea lions by visitors from inappropriate human recreational activities or from visitors trying to elicit a more 'active' sea lion response than the usual 'sleeping or resting' behaviour on display; these impacts included sea lions retreating and leaving the beach, or displaying aggressive behaviour. Impacts on sea lions from these disturbances may range from a potential sea lion physiological stress response to sea lions leaving the beach, a reduction in the time sea lions spend hauling out, and, in the longer term, the risk of sea lions abandoning the site altogether. Repeated instances of visitors (including unsupervised young children) approaching sea lions at very short distances of less than 2.5 m represented a public safety risk. Results also indicated that (1) the numbers of sea lions hauled out and their rate of return to the beach did not appear to be affected by an increase in the level of human visitation (although longer-term studies would be required to confirm this result); and (2) there appeared to be a high turnover rate of sea lions at the site from day to day, suggesting that there are frequent arrivals and departures of sea lions to and from Carnac Island. The visitor survey indicated that many visitors to Carnac Island had a recreational focus that was not primarily directed towards sea lion viewing ('incidental ecotourists'). Although many visitors witnessed incidental disturbance caused by humans to sea lions, they did not seem to recognise that they themselves could disturb sea lions through their mere presence. Visitors also seemed to have a limited awareness of the safety risk posed by sea lions at close range. Visitors expressed support for the presence of a volunteer ranger on the beach and for more on-site information about sea lions. Finally, visitors indicated that they greatly valued their sea lion viewing experience. It is anticipated that the continued increase in visitation to Carnac Island from recreation and from tourism will result in intensified competition for space between humans and sea lions. Long-term impacts of human disturbances on sea lions are unknown, but a physiological stress response and/or the abandonment of haulout sites has been observed in other pinniped species. The findings of this study highlight the need to implement a long-term strategy to reduce disturbance levels of sea lions by visitors at Carnac Island to ensure that tourism and recreation around sea lions can be sustained in the long term. Recommendations include measures to control visitor numbers on the island through an equitable allocation system between various user groups, the development of on-site sea lion interpretation and a public education and awareness program, the setting up of a Sea Lion Sanctuary Zone on the main beach, ongoing monitoring of sea lion and visitor numbers and other data, and a system of training and accreditation of guides employed by tour operators.

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Orsini, Jean-Paul. "Human impacts on Australian sea lions, Neophoca cinerea, hauled out on Carnac Island (Perth, Western Australia) : implications for wildlife and tourism management /." Orsini, Jean-Paul (2004) Human impacts on Australian sea lions, Neophoca cinerea, hauled out on Carnac Island (Perth, Western Australia): implications for wildlife and tourism management. Masters by Research thesis, Murdoch University, 2004. http://researchrepository.murdoch.edu.au/238/.

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Over the last 15 years, pinniped tourism has experienced a rapid growth in the Southern Hemisphere, and particularly in Australia and New Zealand where at least four sites attract more than 100,000 visitors per year. Tourism focused on the Australian sea lion (Neophoca cinerea), a protected species endemic to Australia, occurs in at least nine sites in South Australia and Western Australia. Australian sea lions haul out on several offshore islands in the Perth region. Carnac Island Nature Reserve is one of the main sites where people can view sea lions near Perth, either during recreational activities or on commercial tours. This study sought: (1) to investigate the potential impact of human visitors on Australian sea lions hauled out on Carnac Island, (2) to consider implications of the results for the management of Carnac Island Nature Reserve, and (3) to examine under which conditions tourism and recreation around sea lions can be sustained in the long term. Sea lion numbers, rate of return to the site, behavioural response to human presence and incidents of disturbances of sea lions by visitors were recorded over a period of four months on Carnac Island. A survey of 207 visitors was also carried out. Findings indicated that there were two main types of human impacts on the sea lions: * A specific state of sea lion vigilance induced by low level, but ongoing, repetitive disturbances from human presence, sustained at various approach distances ranging to more than 15 m, vigilance that is different from the behaviour profile observed in the absence of human disturbance, * Impacts resulting from incidental direct disturbances of sea lions by visitors from inappropriate human recreational activities or from visitors trying to elicit a more 'active' sea lion response than the usual 'sleeping or resting' behaviour on display; these impacts included sea lions retreating and leaving the beach, or displaying aggressive behaviour. Impacts on sea lions from these disturbances may range from a potential sea lion physiological stress response to sea lions leaving the beach, a reduction in the time sea lions spend hauling out, and, in the longer term, the risk of sea lions abandoning the site altogether. Repeated instances of visitors (including unsupervised young children) approaching sea lions at very short distances of less than 2.5 m represented a public safety risk. Results also indicated that (1) the numbers of sea lions hauled out and their rate of return to the beach did not appear to be affected by an increase in the level of human visitation (although longer-term studies would be required to confirm this result); and (2) there appeared to be a high turnover rate of sea lions at the site from day to day, suggesting that there are frequent arrivals and departures of sea lions to and from Carnac Island. The visitor survey indicated that many visitors to Carnac Island had a recreational focus that was not primarily directed towards sea lion viewing ('incidental ecotourists'). Although many visitors witnessed incidental disturbance caused by humans to sea lions, they did not seem to recognise that they themselves could disturb sea lions through their mere presence. Visitors also seemed to have a limited awareness of the safety risk posed by sea lions at close range. Visitors expressed support for the presence of a volunteer ranger on the beach and for more on-site information about sea lions. Finally, visitors indicated that they greatly valued their sea lion viewing experience. It is anticipated that the continued increase in visitation to Carnac Island from recreation and from tourism will result in intensified competition for space between humans and sea lions. Long-term impacts of human disturbances on sea lions are unknown, but a physiological stress response and/or the abandonment of haulout sites has been observed in other pinniped species. The findings of this study highlight the need to implement a long-term strategy to reduce disturbance levels of sea lions by visitors at Carnac Island to ensure that tourism and recreation around sea lions can be sustained in the long term. Recommendations include measures to control visitor numbers on the island through an equitable allocation system between various user groups, the development of on-site sea lion interpretation and a public education and awareness program, the setting up of a Sea Lion Sanctuary Zone on the main beach, ongoing monitoring of sea lion and visitor numbers and other data, and a system of training and accreditation of guides employed by tour operators.

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14

Goundie, Elizabeth Thomson. "Quantifying the costs of dive behaviours and foraging strategies in Steller sea lions (Eumetopias jubatus)." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54173.

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Air-breathing divers, such as marine mammals, should adjust their diving behaviours in relation to the depth and density of their prey to minimize the energetic costs and maximize the benefits of foraging. However, there is little experimental data to test these predictions or to develop models to predict the responses of marine mammals to changes in prey availability. The objectives of my study were to 1) determine how changes in prey availability affect dive behaviour and foraging efficiency in Steller sea lions (Eumetopias jubatus) and 2) develop models with data from free-diving captive Steller sea lions to estimate foraging costs in wild animals and evaluate energetic trade-offs between different foraging strategies. I measured the diving metabolic rate, dive durations, and food intake of 4 trained sea lions diving in the open ocean on simulated prey patches of high- or low-densities at 10 m and 40 m. I also measured diving metabolic rates of sea lions performing 4 controlled dive types that allowed me to estimate the separate costs of different dive components (i.e., surface time, bottom time, and transiting to and from depth). I found that animals diving on prey patches with low prey density altered their dive behaviours and spent proportionally less time actively foraging, which ultimately decreased their foraging efficiency. I also found that making single, longer dives were less energetically costly than making multiple shorter dives in a bout, but that the sea lions replenished oxygen stores more efficiently when making a bout of dives. Finally, I determined the metabolic cost of transiting to and from depth (20.5±13.0 ml O₂ min₋¹ kg₋¹) was greater than the cost of foraging during the bottom portion of a dive (13.5±4.1 ml O₂ min₋¹ kg₋¹). With these values, I generated a predictive equation to estimate the diving costs of free-ranging animals. Overall, my results indicate that Steller sea lions do alter their dive behaviour in relation to prey availability and that different foraging strategies have different energetic costs. These results can be used to understand how changes in prey availability affect the overall energy balance and health of Steller sea lions.
Science, Faculty of
Zoology, Department of
Graduate

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15

Berman, Michelle Lea. "Effects of Food Deprivation on Blood Lipid Concentration and Composition in Steller Sea Lions (Eumetopias Jubatus)." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2958.

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Steller sea lions, the largest Otariid, fast during their breeding season; during this time they refrain from ingesting food for a period of 12-43 days. Fasting, while undertaking an extremely energetically demanding activity (breeding and pupping), requires specific physiological adaptations. This study examined the physiological response to fasting of two age classes, juveniles and sub-adults, during the breeding and non-breeding seasons to determine how these animals utilize lipids and the pattern of fatty acid mobilization from lipid stores during fasting. Four juveniles and 5 sub-adults were fasted for one and two weeks, respectively, and blood samples were collected approximately every 3 days for lipid analysis. The concentrations of plasma non-esterified fatty acids (NEFA) were analyzed spectrophotometrically. Serum fatty acid composition was analyzed using gas chromatography (GC) and their individual weight percent (wt %) were correlated with their peak retention time and calculated using the area under each peak. Sixty-nine fatty acids were quantified from each sample. However, only those with concentrations above 0.2 wt. % were included in the analysis. Sub-adult samples were grouped on a percent mass loss basis (0%, 7-8% and 15% mass loss) to facilitate comparison with the juveniles. These data represent the total lipid fatty acid composition of each blood sample. Relative lipid concentration was calculated by multiplying the total lipid fatty acid compositional analysis (wt %) by the NEFA concentrations measured in that respective blood sample. Plasma NEFA concentrations in juvenile Steller sea lions ranged from 1.2 [plus or minus] 0.51 mM to 3.7 [plus or minus] 0.69 during fasting and was within the range of fasting phocids. Concentrations of NEFAs in the sub-adult Steller sea lions ranged from 1.00 mM up to 9.70 mM and were generally higher than fasting phocids. The wt % of only one fatty acid (20:0) was significantly different between the breeding and non-breeding season in fasting juveniles. However, the wt % of seven fatty acids changed significantly during fasting in the juveniles and five of these were most significant in separating the beginning and end of the fasts using principal components analysis. In contrast, the wt % of 10 fatty acids were significantly different during the breeding and non-breeding season fasts of the sub-adults. Additionally, the wt % of 10 fatty acids changed significantly during fasting in the sub-adults and four of these (16:1n-7, 18:2n-6, 20:0, and 20:1n-9) were most significant in separating the beginning and end of the fasts using principal components analysis. These trends reveal the physiological differences between the juvenile and sub-adult Steller sea lions and suggest that the sub-adults may be better physiologically and metabolically adapted to fast than the juveniles in this study.
M.S.
Department of Biology
Arts and Sciences
Biology

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16

Walker, Kristen Amy. "Behavioural and physiological responses of Steller sea lions to invasive marking techniques : evidence of post-operative pain." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27307.

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Marine mammal research often requires marking and tracking animals to collect long-term ecological data, but these procedures may cause pain. The aim of this thesis was to assess the behavioural and physiological effects of invasive marking and tracking techniques used on marine mammals. This thesis consists of 7 chapters, beginning with a general introduction (Ch. 1) and ending with a general discussion (Ch. 7). Chapter 2 reviews the literature on short- and long-term effects of marking and tagging, concluding that the preponderance of studies focus on injuries and behavioural changes and that no research prior to this thesis has assessed post-operative pain in marine mammals. Chapters 3 to 6 describe experiments designed to fill this gap by focussing on pain responses of endangered Steller sea lions to invasive marking (hot-iron branding) and tracking (implanting a tracking device via intra-abdominal surgery) procedures. Seven behaviours associated with post-operative pain were monitored for 3 d pre- up to 12 d post-surgery with the aim of describing behavioural responses after abdominal surgery (Ch. 3) and comparing the efficacy of two analgesic treatments (Ch. 4). In both studies sea lions spent more time with their back arched and standing, and spent less time lying on the ventral side and in locomotion after surgery, regardless of analgesic treatment. Chapter 5 described the behavioural responses of sea lions after hot-iron branding. In the 3 days after branding sea lions spent more time grooming their branded area, less time with pressure on their branded side, and less time in the pool and in locomotion. Chapter 6 assessed physiological (breathing and heart rate) and behavioural responses of anaesthetised sea lions during hot-iron branding. Sea lions had increased heart and breathing rate during and in the minutes after hot-iron branding. Behavioural responses during branding included trembling and head and shoulder movements. These findings illustrate behavioural and physiological responses that can be applied to assessing pain in sea lions, and suggest that more effective analgesic protocols are required to mitigate pain responses after hot-iron branding and abdominal surgery.

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Villegas-Amtmann, Stella. "Seasonal variation in the physiological ecology of the Galapagos (Zalophus wollebaeki) and California (Zalophus californianus ) sea lions /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.

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Jeanniard, Du Dot Tiphaine. "Diet quality and season affect physiology and energetic priorities of captive Steller sea lions during and after periods of nutritional stress." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/404.

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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.

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Monson, Daniel H. "Sea otters (Enhydra lutris) and Steller sea lions (Eumetopias jubatus) in the North Pacific : evaluating mortality patterns and assessing population status at multiple time scales /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.

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Hernandez-Valazquez, Francisco Daniel. "Social and reproductive behaviour of California sea lions (Zalophus californianus californianus) : insights from a molecular and behavioural approach." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437823.

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This thesis examines the social and reproductive behaviour of California sea lions (Za/ophus califomianus) and their importance in species management. Genetic tools were developed for genetic analysis. I isolated and characterized nine microsatellite markers, and also characterized four loci from other species. Time allocation analysis was carried out as the basis for all behavioural components of this study. I found females trade-off time spent in aggression with time spent nursing, while males spent more in aggression at the end of the reproductive season than during the middle stages. Relatedness estimates for the adult population provided insights into unusual levels of male philopatry at the colony of Los Islotes. Almost half of the adult males sampled had at least one first-order relative, and the proportion grew to almost 70% when considering second-order relatives. It is possible that, despite the apparent lack of male dispersal, inbreeding avoidance, possibly through kin recognition, does not promote male dispersal but actively prevents mating among known close relatives, thus increasing the likelihood of male natal philopatry. Parentage analysis provided evidence of two parallel mating strategies in the population. Up to a third of the offspring in a year are sired by out-of-colony males. Since aquatic copulations require cooperation and male philopatry is high in this colony, results could indirectly point towards females choosing their mates. Peace-keeping behaviour of male California sea lions was, for the first time, put into a conflict-resolution a behaviour context. I found that at least 50% of the males exhibit this behaviour, although the duration of each bout is small. Males and females are likely to benefit from peace-keeping behaviour, although further research is required to determine their nature and magnitude. Geographical structuring within the Gulf of California population is highly likely and population size decreases may lead to fragmentation that could prove harmful. I suggest that the relevant IUCN specialist group categorises this population as "conservation dependent".

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Gerlinsky, Carling Dawn. "Oxygen stores, carbon dioxide accumulation and nutritional status as determinants of diving ability of Steller sea lions (Eumetopias jubatus)." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45118.

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The diving ability of marine mammals is limited by body oxygen stores (TBO) and rates of oxygen depletion (diving metabolic rate; DMR), which can be expressed as the calculated aerobic dive limit (cADL). Diving ability must also be influenced by CO₂ production and control of ventilation. I investigated the factors that limit the diving ability of Steller sea lions (Eumetopias jubatus), including the effect of nutritional stress on the cADL. Specifically, I 1) determined the cADL of Steller sea lions by measuring TBO and DMR, 2) determined whether nutritional stress alters the cADL and 3) examined the post-dive elimination of CO₂, and the sensitivity of Steller sea lions to hypercapnia (high inspired CO₂). TBO was estimated from measured blood oxygen stores and body composition―and metabolic rate, breathing frequency and dive behaviour were recorded prior to and during a period of nutritional stress where animals lost ~10% of their mass. Animals breathed ambient, hypercapnic or hypoxic (low O₂) air to experimentally alter pCO₂ levels and decrease rates of CO₂ elimination and O₂ consumption. I found that the TBO (35.9 ml O₂ kg-¹) and cADL (3.0 minutes) in actively diving Steller sea lions were lower than previously reported for other species of sea lions and fur seals. I also found a significant increase in mass-specific DMR and blood volume (resulting in higher TBO) in nutritionally stressed animals that resulted in a longer cADL. Hypercapnia was found to significantly affect ventilation, but had no effect on dive behaviour―and elimination of CO₂ between dives took longer than replenishing O₂ stores. Overall, nutritional stress and hypercapnic conditions did not directly limit the diving ability of the Steller sea lions, but had an indirect effect on foraging efficiency by increasing the time they spent on the surface between dives. Accumulation of CO₂ over several dives in a foraging bout also appeared to reduce foraging efficiency, which likely ultimately limits the time a sea lion spends in apnea and therefore overall foraging duration and net energy intake.

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Briggs, Holly Beth. "Characterizing the winter movements and diving behavior of subadult Steller sea lions (eumetopias jubatus) in the north-central Gulf of Alaska." Texas A&M University, 2005. http://hdl.handle.net/1969.1/5028.

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Recent studies indicate a 70% decrease in the Alaskan Steller sea lion (SSL) population (ca. 5% per year) since the early 1980's. In accordance with a 1997 status classification of the Western Steller sea lion (WSSL) stock as endangered, the "critical habitat" for the species was to be defined. This habitat has now been designated to include 10-20 nautical mile buffer zones around most rookeries and haulouts in the Gulf of Alaska (GOA) and Aleutian Islands. However, these zones were based on limited, summer, foraging data. The primary objective of this study was to characterize juvenile SSL diving behavior and habitat use along the Kenai Peninsula and Prince William Sound (PWS) from winter to spring. Fifteen free ranging, subadult SSL of both sexes were captured and equipped with satellite telemeters at five haulout sites in PWS and Resurrection Bay, Alaska. Telemeters transmitted for an average of 122 days (range 38-181 days). A total of 11,692 locations were received and 217,419 dives recorded. All sea lions exhibited localized movements parallel or close to shore (3-15 km offshore). Young of the year (YOY) exhibited high site fidelity. Older juvenile sea lion lions were less restricted in their movements and traveled greater distances (200-400km) visiting a variety of islands, buoys, and other locations in PWS. Most dives were short (mean duration = 1.1 min) and shallow (mean depth = 10.8 m), with animals diving to an average maximum depth of 193 m. During winter (January and February), many dives (>40%) occurred during the daytime (0900-1500 LT). However, by April and May this pattern shifted and the animals made most of their dives (>40%) during the night (2100-0300 LT). This relationship was more pronounced for dives deeper than 20 m and coincided with the seasonal increase in photoperiod. Subadult SSL, especially YOY, remained within the 20 nautical mile coastal zone during winter and spring. Shallow, nearshore waters provide important habitat during this critical period of transition to nutritional independence. However, more conclusive data on SSL foraging ecology is necessary to better understand locations and depths preferred by the species.

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Ghneim, George Simon. "Environmental risk factors associated with leptospirosis infection in California sea lions (Zalophus californianus) and domestic dogs in the California ecosystem /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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Jurczynski, Kerstin. "Tuberculosis in South American sea lions (Otaria flavescens) - diagnostic options and its epidemiologic importance for other mammals within the zoological garden." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-99710.

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Tuberculosis is a widely spread zoonotic disease caused by acid-fast bacteria of the Mycobacterium tuberculosis complex in a variety of mammalian species. In pinnipeds, tuberculosis has been reported in different captive and wild sea lions and fur seals. The causative agent, Mycobacterium pinnipedii, is part of the M. tuberculosis complex and has shown pathogenicity in other mammalian species including human beings. Since 2000 the Heidelberg zoo has been dealing with tuberculosis in its collection of South American sea lions (Otaria flavescens). After a Malayan tapir (Tapirus indicus) was transferred to a zoological institution in France it transmitted the disease to the other tapirs that succumbed to tuberculosis. Culturing and spoligotyping confirmed the origin, the sea lions at the Heidelberg zoo. An investigation of the sea lion group housed at Heidelberg in addition to different species of mammals living in adjacent exhibits as well as a sea lion, born in Heidelberg but then living in Hamburg, revealed multiple cases of pinniped tuberculosis.

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Himes, Boor Gina Kristine. "Applying novel approaches to old datasets: utilizing opportunistic observations and Bayesian estimation to describe spatial use patterns for Steller sea lions." Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/himes_boor/Himes_BoorG0810.pdf.

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Despite two decades of satellite telemetry studies conducted on Steller sea lions, scientists still lack basic spatially-explicit knowledge about Steller sea lion habitat use. The Platforms of Opportunity data collected by the National Marine Fisheries Service contain Steller sea lion sighting records throughout the species' entire range and have the potential to fill the critical gap in knowledge about what areas Steller sea lions are using. The Platforms of Opportunity data have not previously been used to identify marine mammal habitat because they contain sightings without associated effort records (e.g. time spent surveying or area sampled). In this study a novel approach was used to overcome this issue through development of an effort index that allowed for calculation of effort-corrected Steller sea lion encounter rates. A Bayesian negative binomial model was used to quantify both the encounter rate and the uncertainty surrounding that rate within 15 km² grid cells across the species' entire range. Year-round encounter rate estimates were derived in addition to breeding and non-breeding season encounter rates. Although the results of this analysis confirmed many of the areas known to be important Steller sea lion habitat, several previously unrecognized high-use areas were identified. Current critical habitat designated areas only encompass about 37% of high use areas estimated using this methodology.

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au, jporsini@bigpond net, and Jean-Paul Orsini. "Human impacts on Australian sea lions, Neophoca cinerea, hauled out on Carnac Island (Perth, Western Australia): implications for wildlife and tourism management." Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040520.154341.

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Over the last 15 years, pinniped tourism has experienced a rapid growth in the Southern Hemisphere, and particularly in Australia and New Zealand where at least four sites attract more than 100,000 visitors per year. Tourism focused on the Australian sea lion (Neophoca cinerea), a protected species endemic to Australia, occurs in at least nine sites in South Australia and Western Australia. Australian sea lions haul out on several offshore islands in the Perth region. Carnac Island Nature Reserve is one of the main sites where people can view sea lions near Perth, either during recreational activities or on commercial tours. This study sought: (1) to investigate the potential impact of human visitors on Australian sea lions hauled out on Carnac Island, (2) to consider implications of the results for the management of Carnac Island Nature Reserve, and (3) to examine under which conditions tourism and recreation around sea lions can be sustained in the long term. Sea lion numbers, rate of return to the site, behavioural response to human presence and incidents of disturbances of sea lions by visitors were recorded over a period of four months on Carnac Island. A survey of 207 visitors was also carried out. Findings indicated that there were two main types of human impacts on the sea lions: A specific state of sea lion vigilance induced by low level, but ongoing, repetitive disturbances from human presence, sustained at various approach distances ranging to more than 15 m, vigilance that is different from the behaviour profile observed in the absence of human disturbance, Impacts resulting from incidental direct disturbances of sea lions by visitors from inappropriate human recreational activities or from visitors trying to elicit a more active sea lion response than the usual sleeping or resting behaviour on display; these impacts included sea lions retreating and leaving the beach, or displaying aggressive behaviour. Impacts on sea lions from these disturbances may range from a potential sea lion physiological stress response to sea lions leaving the beach, a reduction in the time sea lions spend hauling out, and, in the longer term, the risk of sea lions abandoning the site altogether. Repeated instances of visitors (including unsupervised young children) approaching sea lions at very short distances of less than 2.5 m represented a public safety risk. Results also indicated that (1) the numbers of sea lions hauled out and their rate of return to the beach did not appear to be affected by an increase in the level of human visitation (although longer-term studies would be required to confirm this result); and (2) there appeared to be a high turnover rate of sea lions at the site from day to day, suggesting that there are frequent arrivals and departures of sea lions to and from Carnac Island. The visitor survey indicated that many visitors to Carnac Island had a recreational focus that was not primarily directed towards sea lion viewing (incidental ecotourists). Although many visitors witnessed incidental disturbance caused by humans to sea lions, they did not seem to recognise that they themselves could disturb sea lions through their mere presence. Visitors also seemed to have a limited awareness of the safety risk posed by sea lions at close range. Visitors expressed support for the presence of a volunteer ranger on the beach and for more on-site information about sea lions. Finally, visitors indicated that they greatly valued their sea lion viewing experience. It is anticipated that the continued increase in visitation to Carnac Island from recreation and from tourism will result in intensified competition for space between humans and sea lions. Long-term impacts of human disturbances on sea lions are unknown, but a physiological stress response and/or the abandonment of haulout sites has been observed in other pinniped species. The findings of this study highlight the need to implement a long-term strategy to reduce disturbance levels of sea lions by visitors at Carnac Island to ensure that tourism and recreation around sea lions can be sustained in the long term. Recommendations include measures to control visitor numbers on the island through an equitable allocation system between various user groups, the development of on-site sea lion interpretation and a public education and awareness program, the setting up of a Sea Lion Sanctuary Zone on the main beach, ongoing monitoring of sea lion and visitor numbers and other data, and a system of training and accreditation of guides employed by tour operators.

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Keech, Aaron L. "Fecal triiodothyronine assay validation using captive Steller sea lions (Eumetopias jubatus) and subsequent application to free-ranging populations to examine nutritional stress." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2817.

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Reduced availability of high energy-content prey (nutritional stress) is a predominant hypothesis to explain the decline of Steller sea lion (Eumetopias jubatus) populations in western Alaska from the late 1970's to the late 1990's. Animals may physiologically respond to consuming insufficient prey by increasing stress levels and decreasing metabolic rates. It may thus be possible to identify nutritional stress by measuring concentrations of glucocorticoids (stress) and thyroid hormones (metabolism) shed in feces. However, techniques to measure thyroid hormone concentrations from Steller sea lion feces have not been developed. We quantified variation of triiodothyronine (T3) and thyroxine (T4) concentrations in Steller sea lion feces following injections of thyrotropin (TSH) into four captive animals. Glucocorticoids (GC) were also assayed to examine any relationship to stimulated thyroid hormone secretion. We found that fecal T3 peaked 48 h post-injection and increased 25-57% in three sea lions (all animals, p=0.03). Pre-injection GC increases indicated stress from isolation for baseline fecal collections, but post-injection increases could not be confirmed as a response to TSH injections or as a product of the study design. The results demonstrated that pre- and post-injection changes in fecal GC and T3 concentrations were consistent with predictions of an increased stress response and metabolic rate within the animals. We then measured T3 and GC concentrations in 834 Steller sea lion fecal samples collected in 2005 and 2006 from 15 sites (haulouts and rookeries) between British Columbia and the Central Aleutian Islands. Overall, GC concentrations did not differ between haulout populations (western 2006 pre-pupping and eastern 2005 post-pupping). Fecal hard-part analyses revealed a lower energy-content diet in the western population, suggesting that diet quality is a relevant hypothesis to explain slightly higher GC concentrations found in the western population, specifically the Aleutian Islands region. However, nutritional stress could not be substantiated through T3 concentrations. The rookeries possessed the highest energy-content diets, but also exhibited a nutritional stress response with a significantly higher GC and lower T3 concentration than either haulout population (possibly related to lactation or decreased foraging opportunities), but T3 comparisons performed at scales of site and region were inconclusive.

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Wierucka, Kaja. "Multimodal mother-offspring recognition in the Australian sea lion, Neophoca cinerea." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS432.

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La reconnaissance joue un rôle important dans les systèmes de communication animale et plusieurs modalités sensorielles sont impliquées à cette fin. Bien que la reconnaissance mère-jeune ait été largement étudiée, il y a un manque d'information sur la reconnaissance multimodale et l'importance relative des différentes modalités dans ce processus. Dans cette thèse, j'ai exploré la communication multimodale chez un mammifère colonial - le lion de mer Australien (Neophoca cinerea). La reconnaissance mère-jeune est connue pour être multimodale chez cette espèce, mais les processus sous-jacents de la reconnaissance olfactive et visuelle, ainsi que les interactions entre les indices acoustiques, visuels et olfactifs, et leurs contributions relatives restent inconnues. Des analyses chimiques ont permis de déterminer si les profils chimiques diffèrent selon le sexe et l'âge, les colonies et les régions corporelles des animaux. La présence de similarités chimiques entre la mère et son petit suggèrent que l'appariement des phénotypes pourrait être utilisé pour la reconnaissance olfactive. J'ai examiné le rôle des indices visuels lors de la reconnaissance mère-jeune et j'ai constaté que les indices visuels spécifiques à l'âge sont utilisés par les femelles pour affiner la recherche de leur petit dans la colonie. Les jeunes ont également la capacité de distinguer divers indices visuels, qui peuvent être utilisés pour identifier les différentes classes de congénères. Enfin, j’ai pu aussi déterminer comment les indices acoustiques, olfactifs et visuels sont utilisés de manière synergique dans le processus d’identification individuel, et les résultats sont interprété dans une perspective coûts-avantages pour démêler les pressions évolutives sur chaque composante de ce système de communication. Si les différents indices sensoriels ont la capacité de transmettre des informations en isolation, leur rôle peut être différent lorsque d'autres indices sensoriels sont présents. Les résultats de cette recherche fournissent des résultats sans précédent, contribuant à une meilleure compréhension de la reconnaissance mère-jeune chez les mammifères, ainsi que des règles générales de communication chez les vertébrés
Recognition plays an important role in animal communication systems and individuals often employ different sensory modalities to enact this activity. Although recognition has been widely investigated, especially for mother-offspring interactions, there is a dearth of information about multimodal recognition and the relative importance and interactions of various sensory cues. In this thesis, I explored multimodal communication in a colonial mammal – the Australian sea lion (Neophoca cinerea). Communication during mother-pup reunions is known to be multimodal in this species, yet the underlying processes of olfactory and visual recognition, as well as the interactions between acoustic, visual and olfactory cues remain unclear. Through chemical analyses, I determined whether chemical profiles differ among sex and age classes, colonies, and body regions of animals. Chemical similarities between mothers and pups indicate that phenotype matching may be used by Australian sea lions for olfactory recognition. I examined the role of visual cues in mother-pup recognition and found that age-specific visual cues assist mothers to refine their search for their offspring in the colony. Pups are capable of distinguishing various visual cues that can be used in the assessment of conspecifics. Having provided baseline information about the role of sensory cues in isolation, I determined how acoustic, olfactory, and visual cues are used in a synergistic way to ensure accurate mutual recognition and then interpreted the results using a cost-benefit perspective to disentangle the evolutionary pressures on each component of this communication system. I showed that although cues have the ability to convey given information in isolation, their role may be different when other sensory cues are present. Furthermore, there is a mutual dependency in the communication system, where the limitations imposed on one participant of the dyad affect cue use by the other. These findings contribute to a better understanding of mammal mother-offspring recognition and communication mechanisms in vertebrates

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Page, Brad. "Niche partitioning among fur seals /." Access full text, 2005. http://www.lib.latrobe.edu.au/thesis/public/adt-LTU20060622.153716/index.html.

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Thesis (Ph.D.) -- La Trobe University, 2005.
Submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the Zoology Dept., School of Life Sciences, Faculty of Science, Technology and Engineering. Research. Includes bibliographical references (leaves 133-152). Also available via the World Wide Web.

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Smith, Jennifer. "Biological influences on the three-dimensional habitat use of juvenile New Zealand sea lions (Phocarctos hookeri) with a squid trawl fishery: Implications for conservation managment." Thesis, Smith, Jennifer (2015) Biological influences on the three-dimensional habitat use of juvenile New Zealand sea lions (Phocarctos hookeri) with a squid trawl fishery: Implications for conservation managment. Masters by Research thesis, Murdoch University, 2015. https://researchrepository.murdoch.edu.au/id/eprint/27774/.

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Background New Zealand (NZ) sea lions (Phocarctos hookeri) are one of the rarest otariids (i.e. eared seals) in the world. They are listed as "Nationally Critical" under NZ conservation policy and are recognized as "Vulnerable" in the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species. Currently, the Auckland Islands population of NZ sea lions is in decline and facing persistent threats from commercial trawl fisheries. This population is at-risk of fisheries interactions which may result in bycatch and/or resource competition, particularly with the Southern Arrow squid (Nototodarus sloani) trawl fishery (referred to as 'SQU6T' in New Zealand fisheries management policy). Bycatch of NZ sea lions in the Southern Arrow squid trawl fishery has been historically biased towards females, and resource limitation from competition with this fishery may also be influencing female fecundity. This female-bias in fishery interactions appears to be a result of sex differences in habitat use among adult NZ sea lions. Recent research suggests that sex differences in habitat use may also extend to juvenile age classes. Juvenile sea lions are particularly susceptible to fisheries-induced resource competition because of: (a) age- and size-specific constraints affecting juvenile foraging success; and possibly (b) greater risk of capture in trawling gear due to weaker swimming and diving capabilities, and inexperience. Understanding juvenile NZ sea lion habitat use in relation to the SQU6T trawl fishery is therefore essential to assessing and managing fisheries interactions. Thesis aims The aims of this Thesis are to: (1) identify discrete behaviours from juvenile NZ sea lion dive data through the development and application of a statistical modelling approach, known as a state-space model (SSM); (2) describe the spatio-temporal features of the vertical distribution of those behaviours, and examine how they are influenced by biological factors; and (3) characterise the horizontal distribution of those behavioural classes, in conjunction with fishing effort, to determine potential demographic biases to the interactions between juvenile NZ sea lions and the Southern Arrow squid trawl fishery. Methodology In a prior study, dive and spatial data were collected by time-depth recording (TDR) and platform-transmitting terminal (PTT) tags fitted to juvenile NZ sea lions from Enderby Island, in the Auckland Islands. The data presented in this Thesis form a subset of those data and comprise TDR and PTT tag data of durations between 8 and 17 days from five juvenile sea lions (three females and two males). The TDR data were used in an innovative particle-filtering SSM, developed by Dowd and Joy (2011), which enables the determination of fine-scale behaviours from high-resolution vertical velocity data. This statistically sophisticated algorithm models stochastic animal movement from short segments of dive data and then predicts latent movement parameters for each segment. These movement parameters are then interpreted for their periodicity to infer the foraging and non-foraging behaviours associated with individuals' dives. Findings Chapter 2 describes the statistical underpinnings of the SSM and how this modelling approach was adapted for use with juvenile NZ sea lion TDR data. This Chapter explored two parameters associated with fitting the model to dive data: time-window length and the model used for variance estimation procedures. The results of this exploration suggested that time-window length is of significant importance to estimating the output parameters used for the behavioural classification of dive data. Furthermore, the results indicated that a larger time window than those tested in this Chapter should be employed in future studies attempting to adapt this particular SSM to juvenile NZ sea lion dive data. Chapter 3 focuses on the influence of several biological characteristics on vertical habitat use in juvenile NZ sea lions, and how these differ when individuals were foraging versus surface swimming. The results of this study can directly inform on the diving behaviours which might predispose particular demographics within the juvenile age-class to direct and indirect fisheries interactions with the SQU6T Arrow squid trawl fishery. Linear Mixed Effects (LME) models were used to examine the influence of age, sex, and mass on mean and maximum dive depth and dive duration, and the results were compared between behavioural classes estimated by the particle-filtering SSM adapted in Chapter 2. The results of the LME models suggest that sex, age, mass, and the interaction between age and mass, all play important roles in juvenile NZ sea lion diving behaviour, influencing both the depths and durations of their dives. Males and larger individuals utilised deeper vertical habitat in general, and for longer durations, than did females or smaller animals. However, females spent greater amounts of time near their depth maxima. Both sexes had deeper and longer dives when foraging opportunistically than when foraging continuously (i.e. pseudo-periodically). Surprisingly, the models also suggested a negative relationship between dive depth and duration and age. This indicates that the high inter-individual variation in diving behaviours, coupled with the small sample size may have distorted the ability of the LME models to generate accurate predictions using age as a model parameter. Collectively, the results of this study indicate that females and larger animals diving to their maximum depths spend the greatest amount of their time within the depth ranges of schooling Arrow squid, potentially putting them at greater risk of interaction with the Arrow squid trawl fishery. Chapter 4 investigates the spatio-temporal overlap between juvenile foraging habitat and the distribution of fishing effort by the SQU6T trawl fishery, and sex differences in habitat use. Spatial data collected by PPT tags were linearly interpolated to the behavioural classifications from the SSM (Chapter 3). This enabled spatial characterisation of juvenile foraging habitat and foraging intensity (a function of time spent foraging within an area). These data were then overlaid to distributions of fishing intensity to examine the potential for sex-biased interactions between juvenile NZ sea lions and the SQU6T trawl fishery. Visual analyses of the spatial distributions of individuals' foraging-specific habitat use suggested that foraging habitat varies between sexes. However, statistical analyses indicated that sexual segregation of foraging habitat was insignificant for the five individuals. Furthermore, the proportion of foraging events and effort within high-use trawling areas of the Arrow squid fishery were exceedingly similar for both sexes, illustrating that juvenile male foraging habitat extends into fishing zones. The results of these preliminary analyses indicate a greater potential for bycatch and resource competition between juvenile males and the Southern Arrow squid trawl fishery than previously suggested. The small sample size and high inter-individual variation in the dive and spatial data made it difficult to validate patterns in the results of analyses on sex differences in juvenile NZ sea lions. Nevertheless, preliminary results from this Thesis support the application of a particle-filtering SSM to behavioural assessments of juvenile NZ sea lions, and their interactions with the Southern Arrow squid trawl fishery. Consequently, this Thesis provides valuable information to support future research pursuing these methods and questions.

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Young, Beth Lyn. "Influence of environment, feeding, and dive activity on the use of heart rate to predict oxygen consumption in resting and diving Steller sea lions (Eumetopias jubatus)." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23511.

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Despite its essential role in bioenergetic modeling, reliable measures of energy expenditure (i.e., oxygen consumption) associated with the different activities of wild animals have remained elusive. Oxygen consumption rate (VO₂) associated with activity can be estimated as a function of heart rate (fh), and the empirical relationship between the two has been determined for several aquatic vertebrates while fasting and resting. However, the simplified fh:VO₂ relationships established from such studies may differ under more complex physiological circumstances, such as when animals are foraging at depth or feeding on prey. I assessed the efficacy of using fh to predict VO₂ in 7 captive Steller sea lions, Eumetopias jubatus, while fasting and feeding at rest (on land or in water) and while diving (up to 40 m in the open ocean). Linear mixed-effects models revealed that environment, amount of food fed, and type of diving activity all altered the fh:VO₂ relationship. They also showed that different linear equations are needed to predict VO₂ from fh for sea lions fasted while on land or in water, but that a single equation can predict VO₂ on land regardless of whether fasted or feeding. When in water, feeding animals a 4, 6, or 12 kg meal changed the fh:VO₂ relationship compared to fasted animals. While fh can reliably be used to predict VO₂ in diving sea lions, the relationship differed between single dive cycles (one dive +surface interval) and dive bout cycles (multiple dives+surface intervals). However, the equation that predicted VO₂ for single dive cycles did not differ from that for sea lions resting on the surface. Neither dive duration, dive depth, nor food consumed significantly affected the fh:VO₂ relationships. Heart rate could be used to predict VO₂ in diving sea lions, but only over complete dive cycles or dive bouts where animals recovered fully from the O₂ debt incurred underwater. Based on these results, separate equations that distinguish among environmental, digestive, and diving states can be employed to accurately predict VO₂ from heart rate in wild Steller sea lions.

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Marcotte, Michelle. "Steller watch : timing of weaning and seasonal patterns in numbers and activities of Steller sea lions (Eumetopias jubatus) at a year-round haulout site in Southeast Alaska." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/31968.

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Variability in length of lactation and maternal association allows otariids flexibility to buffer their young against changes in nutrition. It also increases the chance of their young surviving to sexual maturity, which is particularly important in a declining species such as Steller sea lions {Eumetopias jubatus). Timing of weaning is a critically important event in mammalian development that can affect subsequent aspects of an animal's adult life, and may hold the key to understanding the population dynamics of Steller sea lions. Unfortunately no studies have yet fully documented the behavioural ecology of Steller sea lions outside of the breeding season. The goal of my study was to document suckling behaviour over 13 consecutive months to determine the timing of weaning for male and female Steller sea lions under three years of age at Southwest Brothers Island, Southeast Alaska (July 2004 - July 2005). I also wanted to ascertain the haulout patterns and activity levels of the colony in relation to season, prey availability, time of day, and weather. Finally, I sought to evaluate the feasibility of using an automated, time-lapse camera system to monitor sea lions and its potential for future use. Male Steller sea lions were found to suckle longer than females, with a greater proportion of males than females suckling at one year. Time spent suckling declined with age suggesting that the animals became more independent as they grew older, most likely as they increased their ability to forage successfully on their own. Male sea lions that remained with their mother for longer than one year may have had reduced exposure to predation, and obtained more calories with less energy expenditure from milk, compared to females that became nutritionally independent sooner. As a result, this may provide males with a chance to grow as big as possible, as fast as possible, and increase their ability to hold a territory and have access to mates later in life. The number of sea lions onshore at Southwest Brothers Island was influenced by weather on a daily time-scale, but also displayed seasonal changes that may have been related to prey availability and the timing of breeding. The colony abandoned the island mid-March to mid-April, coinciding with the herring spawn and eulachon runs, which are high-fat species and spatio-temporally predictable prey. High daily variability in numbers of animals at Southwest Brothers likely reflected movement of animals to and from other nearby haulouts. Activity levels varied throughout the year, with proportionally more animals resting in the summer and more animals engaged in low activities in the winter. This suggests a higher behavioural expenditure of energy in the winter, contributing to their need for high quality nutrition. June and July is an optimum time to assess sea lion numbers due to the high number of animals onshore at that time and a greater predictability in sea lion behaviour. The counts obtained from the automated time-lapse camera system's digital images correlated with counts obtained from direct observation (r² = 0.99). The direct counts were on average 22% greater than the digital images. While direct observation is the best method for obtaining a greater variety of data, the camera systems have a good potential to be used to monitor Steller sea lions and other species when researchers cannot be physically present.
Science, Faculty of
Zoology, Department of
Graduate

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Buckles, Elizabeth Louise. "Investigations into the association between Otarine Herpesvirus 1 and endemic cancer in California sea lions (Zalophus californianus) : age class, tissue distribution and in vitro cultivation of the virus /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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Jurczynski, Kerstin [Verfasser], Klaus [Akademischer Betreuer] Eulenberger, Klaus [Gutachter] Eulenberger, and Andreas [Gutachter] Beineke. "Tuberculosis in South American sea lions (Otaria flavescens) - diagnostic options and its epidemiologic importance for other mammals within the zoological garden / Kerstin Jurczynski ; Gutachter: Klaus Eulenberger, Andreas Beineke ; Betreuer: Klaus Eulenberger." Leipzig : Universitätsbibliothek Leipzig, 2012. http://d-nb.info/1238240852/34.

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Browne, Patience. "Some aspects of the reproductive physiology of otariid pinnipeds /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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Thesis (Ph. D.)--University of California, Davis, 2004.
Degree granted in Molecular, Cellular, and Integrative Physiology. Includes bibliographical references. Also available via the World Wide Web. (Restricted to UC campuses)

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Lombo, tombo Swesslath. "Facteurs de contrôle sur le fonctionnement du système turbiditique du Rhône depuis le dernier maximum glaciaire." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0016/document.

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Le fonctionnement des systèmes turbiditiques est directement lié au transfert de sédiment par les fleuves du continent vers le domaine marin. Ce transfert est contrôlé par le climat et le niveau marin. Les fluctuations de ces facteurs de contrôle depuis le dernier maximum glaciaire s’enregistrent ainsi dans les systèmes turbiditiques par des périodes d’activité et d’inactivité des systèmes turbiditiques. À l’échelle du système, l’enregistrement sédimentaire est également contrôlé par la morphologie et les processus sédimentaires. Le système turbiditique du Rhône classé parmi les systèmes turbiditiques argilo-silteux, est le plus grand dépôt sédimentaire du Golfe du Lion (Méditerranée Occidentale). Principalement alimenté par les apports du Rhône, il est actuellement inactif dû à l’éloignement du canyon avec la source sédimentaire (~70 km). L’objectif du travail réalisé est d’y déterminer, à partir de 21 carottes sédimentaires, (1) l’activité turbiditique au cours des derniers 25 ka, (2) le rôle des fluctuations climatiques et eustatiques sur le fonctionnement, (3) le rôle de la morphologie sur la variabilité spatiale et temporelle des dépôts turbiditiques. Le travail se base sur (1) la réalisation d’un cadre chronostratigraphique basé sur les fluctuations du rapport isotopique de l’oxygène (δ18O), les fluctuations du rapport Ca/Fe et sur des datations radiocarbones, (2) la caractérisation des lithofaciès. Les résultats obtenus montrent que (1) le niveau marin est le principal facteur de contrôle qui détermine la position de l’embouchure du fleuve Rhône et sa connexion avec le canyon du Petit-Rhône. (2) la remontée rapide et brève du niveau marin vers 19 ka (19-ka meltwater pulse) est enregistrée par un changement des processus turbiditiques, (3) lors du maximum de bas niveau marin, entre 24 ka et 19 ka BP, la présence des hyperpycnites démontrent la connexion directe entre le fleuve et la tête de canyon ainsi que la capacité du Rhône à produire des courants hyperpycnaux, (4) la morphologie du système turbiditique exerce un contrôle sur les lithofaciès turbiditiques essentiellement par le degré de confinement des courants de turbidité
Turbidite systems are active when they are fed by sediments transported from the shelf to the basin floor. This sediment transfer is mainly controlled by climate and sea level. Fluctuations of these control factors since the Last Glacial Maximum are recorded within turbiditic systems by periods of high deposition separated by condensed intervals. In addition, morphological control and sedimentary processes are internals factors explaining the spatial variability of the sedimentary record along the turbidite system. The Rhone turbidite system is classified among Mud-rich systems; it is the largest sediment body in the Gulf of Lions (Western Mediterranean). It results mainly from the accumulation of sediments supplied by the Rhone River. It is presently inactive because the head of the Petit Rhone canyon is situated at about 70 km from the river mouth. Through analyses of 21 sediment cores collected along this system, we characterized, (1) the turbiditic activity during the last 25 kyr, (2) the role of climatic and sea-level controls on the turbiditic activity, (3) the role of internal factors such as the morphology on the spatial variability of the turbiditic deposition. Our study is based on (1) the realization of a chronostragraphical framework based on oxygen isotope (δ18O) fluctuations, Ca/Fe ratio and 14C AMS dating, (2) the characterization of lithofacies. The results show that: (1) sea-level is the main control factor on the connection between the Rhone canyon head and Rhone River mouth. The Rhone turbidite system is definitely a “low-stand dominant system” in the terminology of Covault et al. (2010). (2) the rapid and short sea-level rise at about 19 ka (19-ka meltwater pulse) is recorded by a shift from hyperpycnal flows to lower-concentration turbidites. (3) The presence of hyperpycnites demonstrates a direct connection between the Petit-Rhone canyon head and the Rhone River mouth favoured by sea-level low-stand conditions from 24 to 19 ka. They also demonstrate the competence of the Rhone River to generate hyperpycnal flows during flood episodes. (4) the morphology of the Rhone turbidite system controls the confinement of the turbidity currents and results in various arrangements of lithofacies

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Hoberecht, Laura K. "Investigating the use of blubber fatty acids to detect Steller sea lion (Eumetopias jubatus) foraging on ephemeral high-quality prey /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5317.

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Ream, Rolf R. "Molecular ecology of North Pacific Otariids : genetic assessment of north fur seal and Steller sea lion distributions /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/5293.

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39

Hennen, Daniel Reneau. "The Steller Sea Lion (Eumetopias jubatus) Decline and the Gulf of Alaska / Bering Sea Commercial Fishery." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/hennen/HennenD1204.pdf.

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The Steller sea lion (SSL) population in Alaska was listed as threatened under the Endangered Species Act in 1991. Several procedural restrictions were placed on the commercial fisheries of the region at that time in an effort to reduce the potential for human induced mortality on sea lions. Several years have elapsed since these restrictions were put into place and questions about their efficacy abound. In an effort to determine whether or not fisheries interventions have helped the SSL population to recover, estimates of the fishing activity of the Bering Sea/ Gulf of Alaska commercial fisheries in the vicinity of individual Steller sea lion rookeries and SSL population trends at those rookeries were made using data from the National Marine Fisheries Service (NMFS) Fisheries Observer Program and Steller Sea Lion Adult Count Database. Fisheries data from 1976 - 2000 were analyzed in relation to SSL population counts from 1956 - 2001, at 32 rookeries from the endangered Western Stock. Linear regression on the principal components of the fisheries data show that a positive correlation exists between several metrics of historical fishing activity and SSL population decline. The relationship is less consistent after 1991, supporting a hypothesis that fishing closures around some of the rookeries have been effective in moderating the localized effects of fishing activity on SSL.

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Fowler, Shannon Leone. "Ontogeny of diving in the Australian sea lion /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.

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41

Marcus, Alan David. "Hookworm infection in the Australian sea lion (Neophoca cinerea)." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/13606.

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For the Australian sea lion (Neophoca cinerea), an endangered keystone predator that demonstrates high rates of pup mortality and limited population recovery, an understanding of the role of infectious disease in influencing pup health, and how it may contribute towards shaping population demography, is a key knowledge gap. This thesis investigated the taxonomy, epidemiology, clinical impact, and management of hookworm infection in N. cinerea to address the hypothesis that hookworm infection is a significant cause of disease and mortality in this species. Hookworms collected from N. cinerea pups were identified and described as a novel species (Uncinaria sanguinis). Transmammary transmission in the immediate post-parturient period was implicated as the predominant route leading to patent hookworm infection in pups; however, in contrast to the fundamental role that colony substrate appears to play in shaping the epidemiology of hookworm infection in other otariid hosts, this thesis determined that all N. cinerea pups are infected with U. sanguinis irrespective of the type of colony substrate and that the intensity of hookworm infection appears to be influenced by colony-specific seasonal differences in host behaviour. The clinical impact of hookworm infection in pups was quantified and the occurrence of seasonal patterns in health parameters and the magnitude of colony pup mortality were related to the dynamics of hookworm infection. In addition, the effectiveness of ivermectin to eliminate hookworm infection was investigated. This thesis determined that U. sanguinis is an important cause of disease and mortality in N. cinerea; this thesis contributes towards an improved understanding of the role of infectious disease in influencing the health status and population demography of this endangered species, informing conservation management and providing a solid foundation for further investigations of the effect of disease on the health status of free-ranging species.

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Gales, Nicholas John. "Breeding biology of the Australian sea lion Neophoca cinerea." Thesis, Gales, Nicholas John (1995) Breeding biology of the Australian sea lion Neophoca cinerea. PhD thesis, Murdoch University, 1995. https://researchrepository.murdoch.edu.au/id/eprint/53087/.

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The breeding biology of the Australian sea lion was investigated throughout its geographic range between December 1987 and February 1992. Sea lions breed on at least 51 islands, 28 in Western Australia and 23 in South Australia. Thirty one of these islands had not been previously reported as sea lion breeding sites. A predictive model is developed to estimate the population size from pup production estimates from these locations. It indicates that pup numbers should be multiplied by between 3.81 and 4.81 to estimate the total population size just before the pupping season begins. Pup production was estimated at 2,432 which led to a total population estimate of 9,300-11,700, considerably greater than earlier estimates. Approximately half of the pup production occurs on five colonies near Kangaroo Island, South Australia. An unusual breeding cycle of 17-18 months has been reported for N. cinerea at Kangaroo Island; this study reports for the first time this unusual breeding cycle on islands throughout this species’ range. No evidence was found for breeding seasons shorter or longer than 17-18 months. The breeding season is not synchronised between islands, as it is in other pinnipeds, and the timing of breeding appeared random between sites. Investigations of the reproductive physiology of this species conducted on Kangaroo Island, South Australia, revealed a 4-5 month embryonic diapause and an 11-12 month placental gestation. This unusually long placental gestation was not associated with the production of a precocious pup, but rather, I hypothesise in this study that foetal growth rate is retarded. Because of the non-seasonal, asynchronous reproductive cycle of N. cinerea the present results indicate that cues for the physiological events of gestation must be endogenous, rather than the exogenous cues hypothesised for other pinnipeds. Throughout the lactation that accompanies gestation, N. cinerea produces milk that is lower in fat (energy) than all but the tropical otariids (30.82 +/- 9.84% SD). Analysis of scats and stomach contents indicate that N. cinerea has a broad diet and feeds on primarily benthic species. Such a diet is well suited to the low energy marine environment exploited by this species, in which there are few, if any, seasonal changes in food availability. Feeding trials indicated that analysis of scats alone is a poor methodology for quantifying diet. In this study I hypothesise that the unique reproductive cycle and physiology of N. cinerea results from living in a stable climate in some of the most biologically poor waters of the world.

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Mauffrey, Marie-Aline. "Impact des variations du climat et du niveau marin sur les canyons sous-marins du Golfe du Lion (France) et de la marge de l'Ebre (Catalogne) au cours du Plio-Quaternaire." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0047/document.

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Les fluctuations du climat et du niveau marin, de plus ou moins grande amplitude, influencent le taux d’érosion sur le continent, le transport de sédiment vers l’océan et sa distribution vers le bassin profond. Les canyons sous-marins, structures érosives de premier abord, sont les zones de transfert privilégiées entre le plateau continental et le bassin profond. Peu d’études se sont concentrées sur la relation entre le remplissage des canyons, l’acheminement des sédiments et les variations du niveau marin. La chronologie de leur mise en place et de leur évolution aux échelles de temps géologiques restent également largement spéculatifs. Ce travail est consacré à la genèse des canyons sous-marins au Plio-Quaternaire sur les marges de l’Ebre et du Golfe du Lion, en Méditerranée occidentale. Cette genèse intervient après la crise de salinité messinienne, qui a conduit au démantèlement par érosion continentale des marges méditerranéennes. Après une initiation par érosion régressive au Pliocène, les canyons sous-marins connaissent un développement majeur lors de la mise en place des cycles climatiques de 100 ka au Quaternaire, en lien avec l’amplification des oscillations du niveau marin pouvant atteindre 150 m. L’utilisation et la comparaison de données sismiques (2D et 3D) de résolution et pénétration différentes, couplées à des calages chrono-stratigraphiques par forages, permettent de mettre en évidence le lien important entre les cycles climatiques de Milankovitch (principalement 100 et 41 ka) et l’architecture des têtes de canyons. Les changements rapides du climat et du niveau marin (cycles de Bond) ont également une influence importante sur le flux sédimentaire et les processus de transport, ainsi que sur la connexion/déconnexion avec les systèmes fluviatiles
Climate and sea-level changes with various magnitudes control continental erosion, sediment transport and its delivery to the deep basin. Submarine canyons, that are erosional features at a first glance, are conduits for sediment transport from the continental shelf to the deep sea. Little studies focused on the relationship between canyon infill, sediment delivery and sea-level variations. The chronology of canyon development and evolution through geological time remains speculative. This thesis is dedicated to the understanding of the genesis of submarine canyons in the western Mediterranean Sea during the Plio-Quaternary. This period occurred after the major erosion of Mediterranean continental margins during the Messinian Salinity Crisis. Canyons were initiated by retrogressive erosion during the Pliocene. They further developed in relation with the amplification of sea-level changes during the Quaternary (up to 150 m). The results are based on a large range of 2D and 3D seismic data resolution and chrono-stratigraphic constraints. The stratigraphic signature of Milankovitch (mainly 100 and 40 ka) is revealed within canyon heads. Rapid climate and sea-level changes (Bond Cycles) have also a distinct signature by controlling the type and amount of sediment delivered in canyon heads, and the connection/disconnection with fluvial systems

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Taylor, Rebecca Lynn. "A multistate mark recapture analysis to estimate reproductive rate in the Steller sea lion (Eumetopias jubatus), an endangered species." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/taylor/TaylorR0509.pdf.

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The Steller sea lion is an endangered species whose reproductive rate estimates need to be updated. The species is divided into two populations: the endangered western population has declined over 80% from historical levels, while the threatened eastern population has been increasing at approximately 3% for the past three decades. The statistically most compelling reproductive rate estimates for this species are based on now out of date population dynamics, and hence are not applicable to current concerns. Extensive recent branding and resighting efforts by the Alaska Department of Fish and Game in Southeast Alaska make possible an updated estimation of eastern population Steller sea lion reproductive rates. However, the complexity of these data required a different statistical approach than is typically used to estimate reproduction in marked and resighted animals. I developed a novel statistical analysis, based upon a multistate mark recapture likelihood function, specifically to analyze the Southeast Alaska Steller sea lion data. The likelihood function estimates a reproductive rate when only adult females (not pups) are marked, female sightability is correlated with reproductive status, state classification uncertainty is present and the population is open to births during many of the resighting intervals. I apply this analysis to the Southeast Alaska Steller sea lion data and estimate a reproductive rate of 0.66 (0.55, 0.77). Not only does this provide a reproductive rate estimate for the eastern population, which is important for monitoring its health, but it also provides a basis for comparison to the endangered western population. Furthermore, the Alaska Department of Fish and Game continues to have an active branding and resighting program. The methods developed here can be applied to future data collected in either population.

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Page, Brad, and page bradley@saugov sa gov au. "Niche partitioning among fur seals." La Trobe University. Zoology Department, School of Life Sciences, 2005. http://www.lib.latrobe.edu.au./thesis/public/adt-LTU20060622.153716.

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At Cape Gantheaume, Kangaroo Island (South Australia), adult male, lactating female and juvenile New Zealand (NZ) and Australian fur seals regularly return to the same colony, creating the potential for intra- and inter-specific foraging competition in nearby waters. I hypothesised that these demographic groups would exhibit distinct foraging strategies, which reduce competition and facilitate their coexistence. I analysed the diet of adult male, adult female and juvenile NZ fur seals and adult male Australian fur seals and studied the diving behaviour of adult male and lactating female NZ fur seals and the at-sea movements of juvenile, adult male and lactating female NZ fur seals. Female diet reflected that of a generalist predator, influenced by prey availability and their dependant pups� fasting abilities. In contrast, adult male NZ and Australian fur seals used larger and more energy-rich prey, most likely because they could more efficiently access and handle such prey. Juvenile fur seals primarily utilised small lantern fish, which occur south of the shelf break, in pelagic waters. Juveniles undertook the longest foraging trips and adult males conducted more lengthy trips than lactating females, which perform relatively brief trips in order to regularly nurse their pups. Unlike lactating females, some adult males appeared to rest underwater by performing dives that were characterised by a period of passive drifting through the water column. The large body sizes of adult males and lactating females facilitated the use of both benthic and pelagic habitats, but adult males dived deeper and for longer than lactating females, facilitating vertical separation of their foraging habitats. Spatial overlap in foraging habitats among the age/sex groups was minimal, because lactating females typically utilised continental shelf waters and males used deeper water over the shelf break, beyond female foraging grounds. Furthermore, juveniles used pelagic waters, up to 1000 km south of the regions used by lactating females and adult males. The age and sex groups in this study employed dramatically different strategies to maximise their survival and reproductive success. Their prey and foraging habitats are likely to be shaped by body size differences, which determine their different physiological constraints and metabolic requirements. I suggest that these physiological constraints and the lactation constraints on females are the primary factors that reduce competition, thereby facilitating niche partitioning.

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Miller, Natalie J. "The evolution of a physiological system the pulmonary surfactant system in diving mammals /." Connect to this title online, 2005. http://hdl.handle.net/2440/37717.

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Pulmonary surfactant is a complex mixture of lipids and proteins that lowers surface tension, increases lung compliance, and prevents the adhesion of respiratory surfaces and pulmonary oedema. Pressure can have an enormous impact on respiratory function, by mechanically compressing tissues, increasing gas tension resulting in increased gas absorption and by increasing dissolved gas tensions during diving, resulting in the formation of bubbles in the blood and tissues. The lungs of diving mammals have a huge range of morphological adaptations to enable them to endure the extremely high pressures associated with deep diving. Here, I hypothesise that surfactant will also be modified, to complement the morphological changes and enable more efficient lung function during diving. Molecular adaptations to diving were examined in surfactant protein C (SP-C) using phylogenetic analyses. The composition and function of pulmonary surfactant from several species of diving mammals was examined using biochemical assays, mass spectrometry and captive bubble surfactometry. The development of surfactant in one species of diving mammal (California sea lion), and the control of surfactant secretion using chemical and mechanical stimuli were also determined. Diving mammals showed modifications to SP-C, which are likely to lead to stronger binding to the monolayer, thereby increasing its fluidity. Phospholipid molecular species concentrations were altered to increase the concentration of more fluid species. There was also an increase in the percentage of alkyl molecular species, which may increase the stability of the monolayer during compression and facilitate rapid respreading. Levels of SP-B were much lower in the diving species, and cholesterol was inversely proportional to the maximum dive depth of the three species. Surface activity of surfactant from diving mammals was very poor compared to surfactant from terrestrial mammals. The newborn California sea lion surfactant was similar to terrestrial mammal surfactant, suggesting that these animals develop the diving-type of surfactant after they first enter the water. The isolated cells of California sea lions also showed a similar response to neuro-hormonal stimulation as terrestrial mammals, but were insensitive to pressure. These findings showed diving mammal surfactant to have a primarily anti-adhesive function that develops after the first entry into the water, with a surfactant monolayer, which would be better suited to repeated collapse and respreading.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

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Lindemann, Kristy L. "Auditory-visual matching and exclusion in a California sea lion /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.

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Brock, Patrick Michael. "Immunity, life history and conservation in the Galapagos sea lion." Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/3398/.

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Infectious disease threatens health and biodiversity across the globe, and disease emergence may become more common as humans further encroach on habitats and modify environments. To assess the risks of disease emergence in natural populations accurately, we require an understanding of the workings of immunity in the wild. This thesis is about immunity in the context of life history in the endangered Galapagos sea lion, and aims to contribute to understanding of immune dynamics in wild populations, and to evidence-based conservation management. The introduction reviews the development of the discipline of ecological immunology, and discusses the application of its methodological tools to little-known species such as the Galapagos sea lion. The first data chapter uses these tools to describe the ontogeny of Galapagos sea lion immunity in two contrasting ecological contexts. The second data chapter contextualises the immune variation described in the first by assessing the relationship between immune activity and condition. The third data chapter introduces a genetic dimension through the analysis of inbreeding estimates with immune measures. The fourth and final data chapter uses epidemiological models to assess the risk of Galapagos sea lion exposure to canine distemper virus under different management and environmental scenarios. The discussion brings together the results of the data chapters and evaluates emergent themes and limitations in the context of suggestions for future work. The results show that the study of immune variation in species such as the Galapagos sea lion can provide useful insight into the dynamics of immunity in the wild, and information that can have practical application to conservation. They also lay a foundation for integrated epidemiological analyses of disease risk that incorporate physiological and immunological variation, and that have potential for constructive development beyond the Galapagos sea lion.

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Carriço, Joana Isabel Almeida. "Genetic diversity of the California sea lion assessed by pedigree analysis." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2021. http://hdl.handle.net/10400.5/21171.

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Dissertação de Mestrado Integrado em Medicina Veterinária
The genetic diversity and population structure of the California sea lion (Zalophus californianus) were assessed based on the pedigree information registered in the European studbook, currently under the management of the Lisbon Zoo, as an EEP programme. Records collected from 1930 until 2020 were used for this analysis, including a total of 1998 individuals, 477 of which represent the current living population. To our knowledge, this is the most comprehensive and up-to-date analysis for this species, assessing the evolution of genetic diversity, inbreeding and relationships, and the genetic contribution of founders, using conventional pedigree analysis procedures and additional software tools commonly used in domestic species, such as ENDOG. The average equivalent complete generations were 1.54 (±1.20) per animal for the overall population. However, there has been an increase in pedigree depth throughout the years, with the reference population reaching 3.37 (±0.76) complete generations, where all animals had maternal grandparents known and nearly 85% to 90% had paternal grandparents known. The whole population had a generation interval of 11.52 (±4.70) years, however the mean ages at which individuals had their progeny has been increasing, particularly in the last decade. Regarding the number of offspring for each parent, dams had an average of 4.05 (±3.16) pups and sires 7.97 (±8.57) pups. The overall mean inbreeding was 2.03% (±5.92), though throughout the years, this has been increasing, with the reference population reaching 3.34% (±6.08). The rate of increase in inbreeding was around 1.6% per generation. The number of inbred animals has also been growing, representing 16.87% and 52.94% of the total and reference populations, respectively. However, the average inbreeding coefficient, of the inbred individuals has shown a significant decrease, with the value for the reference population being nearly half that of the overall population. The mean coancestry among individuals from the same institution of birth, was 0.10, and from different institutions was 0.01, providing the opportunity to maintain inbreeding under control by planned exchange of breeders between institutions. The number of founders contributing to 50% of the gene pool was 36 and 12, for the total and reference populations, respectively, with an effective number of founders of 96 and 34 in the two populations. The effective population size, for the whole population was 36. It is important to maintain a sound program aimed at the genetic management of the population, including management of selection and mating decisions, to avoid further losses of genetic diversity.
RESUMO - Diversidade genética do Leão-marinho Californiano avaliada através da análise do pedigree - A diversidade genética e a estrutura da população de leões-marinhos Californianos (Zalophus californianus) foi avaliada com base nos registos de pedigree do studbook Europeu, sob a gestão do Jardim Zoológico de Lisboa, como um programa EEP. Os registos, recolhidos desde 1930 até 2020, que foram utilizados para esta análise, incluem um total de 1998 indivíduos, 477 dos quais representam a população viva atual. Para nosso conhecimento, esta é a análise mais compreensiva e atualizada desta espécie, que avalia a evolução da diversidade genética, consanguinidade, parentescos, e contribuição genética de fundadores, usando métodos convencionais de análise de pedigree e ferramentas de software adicional, tipicamente usadas para espécies domésticas, como o ENDOG. A média de gerações completas equivalentes foi de 1.54 (±1.20) por animal, para a população total. No entanto, tem havido um aumento na profundidade do pedigree, ao longo dos anos, com a população de referência a alcançar as 3.37 (±0.76) gerações completas, e onde todos os animais tinham avós maternos conhecidos e 85% a 90% tinham avós paternos conhecidos. A população total teve um intervalo de geração de 11.52 (±4.70) anos, no entanto a média das idades às quais os indivíduos tiveram filhos tem vindo a aumentar, particularmente na última década. Em relação ao número de filhos por progenitor, para as fêmeas foi 4.05 (±3.16) crias e para os machos 7.97 (±8.57) crias. A consanguinidade média geral foi de 2.03% (±5.92), embora ao longo dos anos, tenha vindo a aumentar, com a população de referência a alcançar um valor de 3.34% (±6.08). A taxa de aumento da consanguinidade foi de 1.6% por geração. O número de animais consanguíneos tem vindo a aumentar, representando 16.87% e 52.94% das populações total e de referência, respetivamente. No entanto, a média do coeficiente de consanguinidade, dos consanguíneos, mostra uma diminuição significativa, com o valor da população de referência a ser metade do da população total. O relacionamento médio, nos indivíduos da mesma instituição de nascimento foi de 0.10 e de diferentes instituições de 0.01, proporcionando a oportunidade de manter a consanguinidade sob controle por meio da troca planeada entre as instituições. O número de fundadores que contribuíram para 50% do pool genético foi de 36 e 12, para as populações totais e de referência, respetivamente, com um número efetivo de fundadores de 96 e 34, nas duas populações. O tamanho efetivo da população total foi de 36. É importante manter um programa apontado para a gestão genética da população, incluindo o maneio da seleção e decisões de acasalamento, para evitar maiores perdas de diversidade genética.
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Ferdinando, Pilar M. "Assessment of Heavy Metals in Subsistence-Harvested Alaskan Marine Mammal Body Tissues and Vibrissae." Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/504.

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Abstract:

The coastal, indigenous communities around Alaska have subsisted on marine animals for generations, often focusing on large apex predators such as seals, sea lions, and whales. Three species of pinnipeds (harbor seal, Steller sea lion, northern fur seal) and the northern sea otter have all undergone significant population declines since the 1970s, some regions more than others. Archived vibrissae (whiskers) and body tissues from these four species were available from the Bering Sea and throughout the Gulf of Alaska from the 1990s and early 2000s. Tissues from these species are exceedingly difficult to obtain; thus, the archived tissues provided a finite and irreplaceable resource of data. Analysis of these archived tissues indicates which species, tissues, and gender bioaccumulate metals more readily. In this study twelve heavy metals (arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium, vanadium, zinc) were analyzed in vibrissae from the four select species, and in body tissues from harbor seals and Steller sea lions. The samples were collected from three regions (southeastern, southcentral, and southwestern Alaska) during the 1990s through early 2000s. Significant differences of heavy metal concentrations in vibrissae were detected among elements (p2(110) = 454.81, p2(66) = 310.88, p

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