No description available.

Eumetopias jubata is polygyncus. The sea-lions segregate during the breeding season into pupping colonies consisting of adult males and females, and non-pupping colonies consisting mainly of sub-adult males. All previous studies of the social behaviour E. jubata have been concerned only with pupping colonies. This study describes the social behaviour and organization of a non-pupping colony. The colony is located at Mclnnes Island, British Columbia (Lat. 52°16’ N., Long. 128°43’ W.). It consists of 100-150 animals. They are mainly sub-adult males though several adult sea-lions of both sexes were present. Data concerning six age-sex classes were taken using two methods. One method involved the development of an ethogram consisting of 34 behaviour patterns and the observation of social interactions. The other method involved spacial organization and activity. Qualitative notes on territorial and reproductive behaviour as well as population structure were also recorded. A peck-dominance hierarchy exists between the classes and is related to many of the behaviours measured. Males are more socially involved than females. This is more voluntary for males than it is for females. As males mature their behaviour becomes more complex than that of females. Females are not aggressive. This is reflected by their lack of Body Contact behaviour. Males are aggressive towards other males and use more Body Contact behaviour than females. Body Contact behaviour is mainly physical aggressive interaction. As males mature it is replaced with Non-body Contact behaviour which is largely threats and displays. The intense social conditioning of sub-adult males results in more socially adept adults that are better able to cope with the complex society at pupping colonies. Sub-adult males are not territorial. However, some adult males are. This is related to the presence of females. Territories act as refuges for females who avoid areas of activity and harassment by sexually mature sub-adult males. This contributes to the grouping of females around territorial adult males. Non-pupping colonies are spatially organized similar to pupping colonies except for the relative proportion of age-sex classes. Socially, non-pupping colonies are less organized than pupping colonies. Social organization in E. jubata is promoted by the tranquil behaviour of adults and inhibited by the disruptive behaviour of sub-adult males. / Science, Faculty of / Zoology, Department of / Graduate

Worldwide harbour seal populations are showing differing and fluctuating trends in abundance, but the drivers of change remain uncertain. Within the Moray Firth, NE Scotland, count surveys carried out over the last 20 years highlighted the development of a new breeding site, providing a unique opportunity to carry out an individual-based study of harbour seal demography and pupping phenology using photo-identification techniques within a mark-recapture framework. Sightings of individual seals suggested that a large proportion of harbour seals are year-round residents at haul-out sites. Both sexes displayed high levels of between-year breeding site fidelity as well as seasonal variation in their haul-out behaviour. Apparent sex-specific survival rates (0.89♂, 0.97♀) and birth rates (0.88) were high. There was a strong correlation between lactation durations and the timing of pupping, suggesting that shifts in pupping phenology are a result of energetic constraints. This highlights the potential for using the timing of pupping as an indicator of ecosystem conditions. This study provided the first concurrent real-time estimates of survival and fecundity in a naturally regulated population of harbour seals. Demographic parameters and physiological responses indicate that prevailing conditions within the Moray Firth are favourable, and that this population should be recovering. However, observed patterns may also be an artefact of the long-term decline having caused an increase in per capita food availability through the reduction in intra-specific competition. This study highlights the current and long-term importance of individual-based data in understanding population dynamics. Through the identification of sentinel sites around the world, harbour seals could provide a single-species indicator of coastal ecosystem conditions in the Northern Hemisphere.

Thesis (M.S.)--Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2001. / Includes bibliographical references (p. 55-60).

No description available.

Thesis (M.Sc.) -- Memorial University of Newfoundland, 1984. / Bibliography : leaves 86-90. Also available online.

Managing a wild population effectively requires knowledge of the abundance and behaviour of the species. Harbour seals (Phoca vitulina) are usually counted when they come ashore at haul-out sites, and so it is important to understand how the number of seals counted at this time relates to total population size. Satellite telemetry studies confirmed that harbour seals on the west coast of Scotland showed a degree of site fidelity and coastal foraging. Most trips taken by tagged animals involved travelling only 10-30 km from haul-outs and lasted less than a day (mean 21.07 hours, SE = 0.54), although some seals travelled over 100 km. Eighteen percent of the time these tagged seals spent hauled out was in the Special Area of Conservation where they were caught. Individual seals can be recognised from their unique pelage patterns using computer-assisted photo-identification. Capture histories for adult harbour seals at a site in north-west Scotland indicated that the number of seals using the study area between April and October was 3.4 times higher than the number counted during an aerial survey made during the August moult. In the UK, aerial surveys of harbour seals are usually conducted during the first three weeks of August, when seals are moulting. These counts have a coefficient of variation of around 15%. Land-based counts made at study sites on the north-west coast of Scotland indicated that the number of seals hauled out was most consistent during the moult, but highest counts were from the pupping period. Analysis of moult counts indicated that starting surveys one week earlier (on 7th August) and surveying 1½ hours earlier in the tidal cycle would reduce the count variation. There was spatial, seasonal, diurnal and sex-related variation in the proportion of time harbour seals hauled out. Thus the relationship between counts and total population size is likely to vary spatially and temporally. This variation should be included in the estimates of the CV of correction factors. A 5% annual change in harbour seal population size was predicted to take around 14 years to detect based on annual surveys and a CV = 0.15. This detection period increases when monitoring methods with lower precision are used, or surveys are made less frequently. Trends in seal abundance at pairs of haul-out sites were not synchronous and so it is unlikely that counts from small land-based protected areas, such as Special Areas of Conservation, can be used to monitor overall population status.

The effects of habitat features on the distribution of ringed seals (Phoca hispada) in the fast ice of Barrow Strait were examined between March and June 1984 to 1986. Breathing hole density in thirty-two, 2-4 km$ sp2$ study plots provided an index of seal abundance. Densities of seal holes were determined using a combination of trained dogs to locate the subnivean breathing holes and removal sampling. / Birth lairs were not seen before 4 April, but the incidence of these structures increased as the season progressed. Structures maintained by male seals were evident in late March, but were not found after mid-May. In 1984, densities of seal holes were correlated with ice thickness. In 1985, no relationship was detected between seal hole density and habitat. In 1986, the highest densities of subnivean structures including birth lairs, were associated with deep snow conditions located in areas of late consolidating ice. No relationship was identified between the density of male structures and any habitat variables. / The mean reproductive rate for females $>$7 years old was 0.64. Between March and June for adult males lost 204 g per day with 72% of this weight being lost from blubber. Pregnant females lost 467 g per day with 68% of the loss occurring from the blubber. In adult seals no differences in body condition were detected between sexes or between years, but juveniles collected in 1986 were in significantly better condition than juveniles collected in 1984 and 1985.

No description available.

Studying the diet of marine top predators is important for understanding the trophic ecology of the predators but also the distribution, abundance and seasonal variation of prey species. Dietary studies on subantarctic fur seals (Arctocephalus tropicalis) and Antarctic fur seals (A. gazella) is important for assessing their role as predators in the Southern Ocean. Seven hundred and sixty four scats were collected from an A. tropicalis colony at Cape Davis while 659 scats were collected from an A. gazella colony at Watertunnel stream from April 2006 to March 2010. Hard remains such as fish otoliths and cephalopod beaks were used for identification and quantification of prey. A. tropicalis diet comprised of three animal groups (fish, cephalopod and crustaceans) while A. gazella diet was made up of four animal groups (fish, cephalopods, crustaceans and seabirds). Fish contributed substantially more than other prey items in the diet of both fur seal species over the study period. Both species fed predominantly on fish of the family Myctophidae which constituted a numerical abundance of 98.9 percent in scats for both species combined. A. tropicalis fed on fish prey species from eight families, namely: Myctophidae, Notosudidae, Paralepididae, Nototheniidae, Bathylagidae, Chlorophthalmidae, Sternoptychidae and Photichthyidae while A. gazella fed on fish from six of these families, with Chlorophthalmidae and Photichthyidae not represented in its diet. Cephalopods and crustaceans were found in low numbers in the diet of both seal species and seabird remains were only found in the diet of A. gazella. Numerically, the most dominant species were from the genus Gymnoscopelus followed by Protomyctophum and then Electrona. In the diet of A. tropicalis, Gymnoscopelus contributed 66 percent, Protomyctophum 18 percent and Electrona 5.9 percent while in the diet of A. gazella Gymnoscopelus, Protomyctophum and Electrona contributed 59.43 percent, 20.24 percent and 14.24 percent respectively. Gymnoscopelus species comprised G. piabilis, G. bolini, G. braueri, G. fraseri, and G. nicholsi; Protomyctophum comprised Protomyctophum bolini, P. choriodon and P. tenisoni while Electrona comprised Electrona antarctica, E. carlsbergi and E. subaspera. Gymnoscopelus piabilis was the most dominant species from this genus while Electrona carlsbergi and Protomyctophum tenisoni dominated the genus Electrona and Protomyctophum respectively. The total number of fish species utilised by A. tropicalis was twenty four while twenty three fish species were identified in A. gazella diet. Bathysauropsis gracilis only featured in the diet of A. tropicalis while Lampanyctus ater and Lepidonotothen larseni were only found in the diet of A. gazella. To compare the diet of the seal species between seasons, a year was divided into three seasons, early summer, late summer and winter. Their diet was also compared between years from 2006 to 2010. Myctophid fish species showed substantial seasonal and annual fluctuations in the diet of the two fur seal species. E. carlsbergi, G. nicholsi and G. piabilis increased in numerical abundance in winter while Melectrona ventralis increased in late summer. The numerical abundance of G. fraseri and P. tenisoni increased in early summer. Generally, the two fur seal species fed on the same prey species. However, there was a significant difference when the diet of both fur seals was compared seasonally. There was no significant difference when the diet of A. gazella was compared annually, although such a difference was apparent for A. tropicalis.