Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 Introduction
- 2 Effects of fisheries on ecosystems: just another top predator?
- 3 Physical forcing in the southwest Atlantic: ecosystem control
- 4 The use of biologically meaningful oceanographic indices to separate the effects of climate and fisheries on seabird breeding success
- 5 Linking predator foraging behaviour and diet with variability in continental shelf ecosystems: grey seals of eastern Canada
- 6 Distribution and foraging interactions of seabirds and marine mammals in the North Sea: multispecies foraging assemblages and habitat-specific feeding strategies
- 7 Spatial and temporal variation in the diets of polar bears across the Canadian Arctic: indicators of changes in prey populations and environment
- 8 Biophysical influences on seabird trophic assessments
- 9 Consequences of prey distribution for the foraging behaviour of top predators
- 10 Identifying drivers of change: did fisheries play a role in the spread of North Atlantic fulmars?
- 11 Monitoring predator–prey interactions using multiple predator species: the South Georgia experience
- 12 Impacts of oceanography on the foraging dynamics of seabirds in the North Sea
- 13 Foraging energetics of North Sea birds confronted with fluctuating prey availability
- 14 How many fish should we leave in the sea for seabirds and marine mammals?
- 15 Does the prohibition of industrial fishing for sandeels have any impact on local gadoid populations?
- 16 Use of gannets to monitor prey availability in the northeast Atlantic Ocean: colony size, diet and foraging behaviour
- 17 Population dynamics of Antarctic krill Euphausia superba at South Georgia: sampling with predators provides new insights
- 18 The functional response of generalist predators and its implications for the monitoring of marine ecosystems
- 19 The method of multiple hypotheses and the decline of Steller sea lions in western Alaska
- 20 Modelling the behaviour of individuals and groups of animals foraging in heterogeneous environments
- 21 The Scenario Barents Sea study: a case of minimal realistic modelling to compare management strategies for marine ecosystems
- 22 Setting management goals using information from predators
- 23 Marine reserves and higher predators
- 24 Marine management: can objectives be set for marine top predators?
- Index
- References
7 - Spatial and temporal variation in the diets of polar bears across the Canadian Arctic: indicators of changes in prey populations and environment
Published online by Cambridge University Press: 31 July 2009
Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 Introduction
- 2 Effects of fisheries on ecosystems: just another top predator?
- 3 Physical forcing in the southwest Atlantic: ecosystem control
- 4 The use of biologically meaningful oceanographic indices to separate the effects of climate and fisheries on seabird breeding success
- 5 Linking predator foraging behaviour and diet with variability in continental shelf ecosystems: grey seals of eastern Canada
- 6 Distribution and foraging interactions of seabirds and marine mammals in the North Sea: multispecies foraging assemblages and habitat-specific feeding strategies
- 7 Spatial and temporal variation in the diets of polar bears across the Canadian Arctic: indicators of changes in prey populations and environment
- 8 Biophysical influences on seabird trophic assessments
- 9 Consequences of prey distribution for the foraging behaviour of top predators
- 10 Identifying drivers of change: did fisheries play a role in the spread of North Atlantic fulmars?
- 11 Monitoring predator–prey interactions using multiple predator species: the South Georgia experience
- 12 Impacts of oceanography on the foraging dynamics of seabirds in the North Sea
- 13 Foraging energetics of North Sea birds confronted with fluctuating prey availability
- 14 How many fish should we leave in the sea for seabirds and marine mammals?
- 15 Does the prohibition of industrial fishing for sandeels have any impact on local gadoid populations?
- 16 Use of gannets to monitor prey availability in the northeast Atlantic Ocean: colony size, diet and foraging behaviour
- 17 Population dynamics of Antarctic krill Euphausia superba at South Georgia: sampling with predators provides new insights
- 18 The functional response of generalist predators and its implications for the monitoring of marine ecosystems
- 19 The method of multiple hypotheses and the decline of Steller sea lions in western Alaska
- 20 Modelling the behaviour of individuals and groups of animals foraging in heterogeneous environments
- 21 The Scenario Barents Sea study: a case of minimal realistic modelling to compare management strategies for marine ecosystems
- 22 Setting management goals using information from predators
- 23 Marine reserves and higher predators
- 24 Marine management: can objectives be set for marine top predators?
- Index
- References
Summary
Polar bears (Ursus maritimus) are broadly distributed in the Arctic and, as such, have the potential to provide information about changes in ecosystem structure and functioning over broad scales in time and space. Yet, because they are so wide-ranging and difficult to observe, there are few quantitative data on polar bear diets or on the ecological (e.g. climate change) and demographic factors that influence prey selection. We used quantitative fatty acid signature analysis of polar bear adipose tissue to estimate their diets in the 1980s/90s across three major regions of the Canadian Arctic: Davis Strait (n = 70), western Hudson Bay (n = 217) and the Beaufort Sea (n = 34), using a database of the major prey species in each region (n = 292). Although polar bears consumed ringed and bearded seals throughout their range, diets differed greatly among regions. Ringed seals accounted for ≥98% of diet in the Beaufort Sea. In western Hudson Bay, ringed seals accounted for about 80% of intake in the early 1990s, indicating the importance of foraging in ice-covered habitat. However, ringed seal consumption declined throughout the 1990s concurrent with progressively earlier ice breakup, while the proportions of bearded and harbour seals increased, suggesting reduced reliance on ice. Throughout Davis Strait, harp seals comprised 50% of bears' diets, consistent with the increase in the harp seal population in this region. Off southern Labrador near the whelping patch, harp seals accounted for 90% of diets.
- Type
- Chapter
- Information
- Top Predators in Marine EcosystemsTheir Role in Monitoring and Management, pp. 98 - 117Publisher: Cambridge University PressPrint publication year: 2006
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