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Hauling out behaviour of harbour seals : (Phoca vitulina richardsi), with particular attention to thermal constraintsWatts, Peter January 1991 (has links)
Harbour seals throughout their range are known to "haul out" onto land according to a daily cycle, which has never been fully investigated. This cycle may represent a tradeoff between the need to forage and the need to avoid aquatic predators; if so, seals should forage when prey availability is greatest and remain hauled at other times. A model based upon these premises accounted for approximately two thirds of the variation in observed hauling behaviour at a harbour seal colony in the Strait of Georgia, once other environmental effects had been filtered from the data. Some such effects could not be corrected for; since air temperature and solar radiation follow the same general pattern as that predicted by the hauling model, the possibility that hauling occurs in response to thermal conditions could not be excluded. This issue was addressed by correlating hauling activity at three seal colonies with "flux" Fs, an index of heat exchange between a seal and its environment. Once time of day and tidal effects were accounted for, there was no evidence of a positive correlation between hauling and Fs. However, under warm summer conditions there was a steep negative relationship. This is consistent with the possibility that hauled harbour seals are vulnerable to hyperthermia due to their adaptation to an aquatic lifestyle; the same blubber layer which keeps them warm when immersed may make it difficult for them to lose excess heat when on land. This was confirmed by a series of controlled experiments. Captive seals overheated when exposed to a radiant thermal environment similar to that in which wild animals stopped hauling. These data allowed me to derive an equation which described the rate of change in a seal's core temperature as a function of both present core temperature and Fs. I incorporated this function into a simulation model which described hauling behaviour in terms of a foraging/predator-avoidance tradeoff. The model performed well when used to predict the haul out durations of a sample of wild radio-tagged harbour seals in a known thermal environment. However, it is apparent that the processes which constrain hauling in this species are somewhat better understood than those which presumably cause it. An understanding of the foraging efficiency of harbour seals throughout the day, and of the predation risks they face, is probably fundamental to an understanding of hauling; yet these issues remain virtually unexplored. / Science, Faculty of / Zoology, Department of / Graduate
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Ecology, tourism and management of harbour seals (Phoca vitulina)Granquist, Sandra M. January 2016 (has links)
In cases where human and wildlife are co-using the same geographical areas and resources, management issues often get complex and stakeholder conflicts are common. The Icelandic harbour seal (Phoca vitulina) population is rapidly decreasing, but direct culling of seals still occurs. At the same time seals are becoming an important resource due to increased interest in wildlife watching. Despite the complicated management situation, the Icelandic harbour seal population is one of the least studied pinniped populations in the world. Mapping the typical haul-out pattern is an important foundation for further studies. In paper I haul-out behaviour of harbour seals was investigated and a seasonal haul-out pattern was detected with the maximum number of seals hauling out during summer. A bimodal distribution curve was found during the summer time, suggesting that pupping period occurs in late May to early June, while moulting occurs in late July to early August. Tidal state, air-temperature and wind-speed affected the haul-out boots. Today, the main reason for culling harbour seals in Iceland is to reduce harbour seal predation on salmonids, despite limited knowledge on the effect of seal predation on salmonid populations and salmon angling. The diet of harbour seals that haul out in the estuary area of Bjargós and Ósar in NW-Iceland was therefore investigated using hard-part (paper II) and DNA metabarcoding analysis (paper III). Both methods showed that the main prey species were sand eels, flatfishes, gadoids, herring and capelin, while salmonids were not an important prey in this area. Based on these results, culling of harbour seals in the area is not likely to have a positive effect on salmonid angling. These results have crucial management implications, especially in the light of the severe decline in the Icelandic harbour seal population. Potential effects of seal watching tourism on the harbour seal population must also be considered in management plans. In paper IV, we investigated the effects of land based seal watching on seal behaviour and found that spatial distribution and vigilance was affected by tourists. Calm tourists behaviour had less effect, meaning that disturbance could be reduced if tourist behaviour is modified. In paper V, this line of investigation was followed by analysing knowledge transfer from academia to the tourist industry and a model was presented where a synergy effect of working interdisciplinary is hypothesised. Finally, in paper VI, the effect of signage on tourist behaviour was studied. Empirical testing showed that teleological information is more effective than ontological in terms of modifying general tourist behaviour. In this thesis, I present new knowledge on behaviour and diet of harbour seals, as well as new empirical findings on tourist behaviour in wildlife tourism settings. Further I explore interdisciplinary management approaches for seal watching tourism. The findings presented in this thesis have an important value within academic research in environmental-, life- and social sciences and the knowledge can be applied in several areas of harbour seal management in Iceland and elsewhere. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 6: Manuscript.</p>
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A comparison of diversity in the zfy gene in two species of pinnipeds with different breeding strategiesSweny, Jason Michael 12 April 2006 (has links)
Sequence variation was examined for the Zinc-finger Y (zfy) gene and the
mitochondrial control region for two species of pinnipeds, the Steller sea lion
(Eumetopias jubatus) and harbor seal (Phoca vitulina). The two species differ in aspects
of their breeding strategies, dispersal, and life histories. Comparable stock sample sizes
of males from each species were taken from localities that span at least one wellrecognized
phylogeographic stock as defined by mtDNA markers. Variation in zfy, a
strictly paternally inherited marker located on the Y chromosome, was low in both
species. An interesting pattern of subdivision was found for zfy in harbor seals that was
concordant with population subdivision for mtDNA. In Steller sea lions, no such
concordant pattern was evident with only a single rare zfy variant being observed. One
explanation for the different patterns observed is that dispersal is less in male harbor
seals than in male Steller sea lions.
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The seasonal movements and abundance dynamics of the Pacific harbor seal (Phoca vitulina richardsi) along the southern Oregon coastWilson, Michael Turner January 1993 (has links)
Typescript.
Includes vita and abstract.
Bibliography: Includes bibliographical references (leaves 84-90).
Description: xiv, 90 leaves : ill. ; 29 cm.
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Évaluation des changements pathologiques pulmonaires induits par l'infection expérimentale de phoques du Groenland par le nématode pulmonaire Otostrongylus circumlitusPiché, Caroline January 2007 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mother-pup interaction and the impact of anthropogenic disturbance in wild harbour seals (Phoca vitulina)Groothedde, Julia January 2011 (has links)
This study investigated the abundance of harbour seals (Phoca vitulina) on inter-tidal sandbanks, mother-pup interactions as well as the impact of anthropogenic disturbance during breeding season. The abundance was a composite picture of harbour seals of different age and sex, and increased gradually towards peaks in June. Although the sandbank water inlet was the longest time emerged, mother-pup pairs and other seals hauled out more abundant on the other sandbanks, probably due to space availability, differences in sandbank structure and distance to human activity. Mothers and their offspring were found to be mostly inactive during haul out. Mothers initiated significantly more frequently interactions i.e. hauling out, entering water and suckling. Seals hauled out at sandbanks close to the dyke were most frequently disturbed by pedestrians. Important regarding the impact on the seals seemed to be the group size of pedestrians and the distance to the seals (on dyke or seaside of it), i.e. pedestrians seaside disturbed more seals. This applies also to the disturbance by marine activity, e.g. distance of seals to the engine boat. Jet fighters were shown to affect the highest mean number of seals per event. After anthropogenic disturbances separations of mother and offspring were not recorded, e.g. due to seals being in the water; however, the steep edges as result of the culvert at water inlet lead to a few separations. The most frequent behavioural response towards anthropogenic disturbance was commotion with a probably lower level of energy costs during the energy consuming lactation period.
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Inter and intra specific interactions in marine habitat selection of two sympatric seal species in Northeast Atlantic / Interactions intra et inter-spécifiques dans la sélection d’habitat de deux espèces sympatriques de phoques dans l’Atlantique Nord-EstHuon, Mathilde 28 November 2017 (has links)
La plasticité comportementale et les interactions entre organismes sont connues pour avoir une influence sur l’utilisation de l’espace, notamment la sélection de l’habitat de chasse. Dans l’Atlantique Nord-Est, les phoques gris et veaux marins vivent en sympatrie. Ces deux espèces sont réparties dans différentes colonies où les interactions entre organismes (liées à la taille de la colonie et à la présence simultanée ou non des deux espèces) ainsi que la disponibilité de l’habitat (et donc des proies) varient localement. L’objectif de cette thèse était d’étudier l’utilisation spatiale et la sélection d’habitat de chasse à l’échelle locale de ces deux espèces dans des situations contrastées de dynamique de colonies. Pour cela, plusieurs individus de différentes colonies situées en Irlande, en Écosse et en France ont été équipés de balises GPS/GSM. Les données récoltées ont permis de caractériser leurs trajets en mer ainsi que d’identifier les zones de chasse permettant par la suite la sélection d’habitat. Contrairement aux veaux marins, qui ont réalisé des déplacements restreints aux alentours des colonies, la plupart des phoques gris se sont déplacés entre différentes colonies. Ainsi, l’étude de la sélection d’habitat à l’échelle individuelle pour les individus se déplaçant entre différentes colonies a mis en évidence l’influence de la plasticité comportementale et suggéré celle de la personnalité de l’animal. A l’échelle de la colonie, chez les deux espèces, les résultats ont mis en évidence l’influence de la disponibilité de l’habitat (et indirectement de la disponibilité des proies) ainsi que des interactions intra-spécifiques (liée à l’effet de densité dépendance) sur l’utilisation spatiale et la sélection de l’habitat de chasse. Cependant, la sélection de l’habitat de chasse était principalement liée à la distance au reposoir et la bathymétrie. Ces deux paramètres sont liés aux caractères de chasseur à place centrale et benthique des phoques. Cette étude a également mis en évidence, pour les sites où les deux espèces étaient présentes, une certaine ségrégation spatiale et des différences de sélection d’habitat entre les deux espèces. / The behavioural plasticity and the interactions between organisms are known to influence foraging habitat selection and spatial usage. In the Northeast Atlantic, greyand harbour seals live in sympatry. These two species are spread into different colonies where interactions between organisms (linked to the colony size et and the presence of one or both species) and habitat availability (linked to the prey distribution) vary locally. The objective of this PhD was to study the spatial usage and foraging habitat selection of these two species at the local scale, in contrasted situations of population dynamics. Several individuals were tagged with GPS/GSM tags in different colonies located in Ireland, Scotland and France. Telemetry data was used to characterize the seals’ trips at sea and to identify their foraging areas in order to model foraging habitat selection. While harbour seals only performed trips restricted around their haulout sites, grey seals moved between colonies. Studying habitat selection at the individual scale, for individuals moving between colonies, highlighted the influence of behavioural plasticity and suggested the influence of individual personality. At the colony scale, for both species, results highlighted the influence of habitat availability (indirectly linked to prey availability) and intra-specific interactions (linked to density dependence effects) on spatial usage and foraging habitat selection. However, the foraging habitat selection was mainly explained by the distance from the last haulout and the bathymetry. These two parameters are linked to the central place forager and benthic feeder characteristics of the seals. Furthermore, this study also highlighted, for study sites where both species occur, a spatial segregation and differences in foraging habitat selection between grey and harbourseals.
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Harbor seal predation and fishery effects on Kattegat-Skagerrak cod abundance : in the aftermath of Phocine distemper virusHökby, Lovisa January 2021 (has links)
The recovering harbor seal population along the Swedish west coast has coincided with declining cod stocks. Although the cod stocks were primarily depleted by intense fisheries, some stakeholders argue that reduced seal populations could have direct, positive effects on the cod stocks. The outbreaks of Phocine distemper virus (PDV) in 1988 and 2002 when up to 66% of the harbor seals along the Swedish west coast died, could be viewed as natural experiments allowing for assessment of any positive impacts of reduced mortality from seal predation on cod abundance. I quantified removal from seal predation and fishery landings and analyzed correlations to cod abundance of different length classes. Analyses were conducted for a longer time- series, 1979-2019, reaching back to when removal from fisheries was substantially larger than that from seal consumption. I also analyzed the data with a more recent perspective, 2003-2019, starting after the later PDV outbreak when seal predation relative landing sizes has increased. During this period, fishery discard data is available and included in the models. Methods include graphical presentation, multiple linear regression analyses, and to expand the existing data on seal diet, I collected diet samples of harbor seal feces from two haul-outs in Skagerrak. No statistically significant, negative correlations between seal predation and cod abundance were found in any data set, hence, I cannot support the idea of harbor seals having an impact on cod abundance. Also, the significant correlations between cod abundance and landings were all positive. I argue that culling of seals cannot be motivated as a strategy to help cod recover, as this would jeopardize the persistence of the seal population rather than assuring cod stability.
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Über die Entstehung von "Heulern" im Nationalpark Niedersächsisches Wattenmeer / The causes behind the abandoning of seal pups in the Wadden Sea National Park of Lower SaxonyLienau, Peter 10 December 2010 (has links)
No description available.
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Genetic Substructure of Pacific Harbor Seal (Phoca vitulina richardsi) Populations Along the Coasts of Oregon and WashingtonDishman, Diana Lynn 01 January 2011 (has links)
It has been assumed that the considerable dispersal ability of many marine species would prevent genetic divergence in the absence of geographic isolation. However, recent work has shown that many marine species often develop differentiation among areas within their known dispersal range. This 'paradox' of marine divergence is particularly important among marine mammal species where behavior can restrict gene flow. To investigate genetic substructure within such a species, I used tissue samples collected from 63 stranded Pacific harbor seals (Phoca vitulina richardsi) in Washington and Oregon between 2006 and 2010 for population stock analysis. DNA was extracted from frozen tissues, and a 551 bp fragment of mtDNA control region sequence and eight microsatellite loci were amplified to investigate localized genetic structure. Minimum spanning network and haplotype frequency analyses of mtDNA sequences indicated that while haplotype lineages are not isolated within a sampling region, there is some evidence of regional differentiation. On the other hand, microsatellite data suggest a lack of substructure among the animals sampled, with only a weak signal of limited gene flow between Puget Sound and coastal areas. Biased dispersal among age classes was also suggested, with juveniles showing less differentiation among areas than adults. Regardless of the historical scenario which has led to this complex pattern of genetic structure in Pacific harbor seals across the Pacific Northwest, my results suggest higher levels of exchange among areas than previously suspected, and will have important consequences for future management considerations for these stocks.
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