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
19 - The method of multiple hypotheses and the decline of Steller sea lions in western Alaska
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
In recent years, enormous effort has been expended to explain the cause of the precipitous decline of the western population of Steller sea lions (Eumatopias jubatus) since the late 1970s; however, despite these efforts and the proposal of a wide variety of hypotheses, the decline has proven to be very difficult to explain. The authors of a recent comprehensive review of the problem emphasized repeatedly that the system is in dire need of a modelling approach that takes advantage of the data available at small spatial scales (at the level of the rookery). We view this as an opportunity for ecological detection, a process in which multiple hypotheses simultaneously compete and their success is arbitrated by the relevant data. We describe ten hypotheses for which there are sufficient data to allow investigation, a method that allows one to link various sources of data to the hypotheses and the conclusions from this approach.
The decline of the western Alaska population of Steller sea lions has proven to be very difficult to explain, in part because most aspects of the population and the environmental variables proposed to explain its decline involve a combination of high spatial and temporal variability, and limited data. Consequently, most researchers pooled data across rookeries or across time, obscuring spatial and/or temporal patterns (Fig. 19.1). Some of these previous studies are described below.
- Type
- Chapter
- Information
- Top Predators in Marine EcosystemsTheir Role in Monitoring and Management, pp. 275 - 293Publisher: Cambridge University PressPrint publication year: 2006
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