Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina
1. Between the 1950s and 1990s the southern elephant seal Mirounga leonina underwent large decreases in population size throughout most of its breeding range in the Southern Ocean. While current population estimates suggest a recent recovery, some breeding populations have continued to decrease in r...
Published in: | Mammal Review |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Blackwell Publishing Ltd
2005
|
Subjects: | |
Online Access: | https://doi.org/10.1111/j.1365-2907.2005.00055.x http://ecite.utas.edu.au/34661 |
id |
ftunivtasecite:oai:ecite.utas.edu.au:34661 |
---|---|
record_format |
openpolar |
spelling |
ftunivtasecite:oai:ecite.utas.edu.au:34661 2023-05-15T16:05:10+02:00 Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina McMahon, CR Bester, MN Burton, HR Hindell, MA Bradshaw, CJA 2005 https://doi.org/10.1111/j.1365-2907.2005.00055.x http://ecite.utas.edu.au/34661 en eng Blackwell Publishing Ltd http://dx.doi.org/10.1111/j.1365-2907.2005.00055.x McMahon, CR and Bester, MN and Burton, HR and Hindell, MA and Bradshaw, CJA, Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina , Mammal Review, 35, (1) pp. 82-100. ISSN 0305-1838 (2005) [Refereed Article] http://ecite.utas.edu.au/34661 Earth Sciences Oceanography Physical Oceanography Refereed Article PeerReviewed 2005 ftunivtasecite https://doi.org/10.1111/j.1365-2907.2005.00055.x 2019-12-13T21:13:22Z 1. Between the 1950s and 1990s the southern elephant seal Mirounga leonina underwent large decreases in population size throughout most of its breeding range in the Southern Ocean. While current population estimates suggest a recent recovery, some breeding populations have continued to decrease in recent years (Macquarie and Marion Islands), others have either remained stable (South Georgia, Kerguelen and Heard Island) or have increased (Peninsula Valds, Argentina). 2. Intrinsi c hypotheses for patterns of regional decline include factors that are affected by density-dependent mechanisms: (i) paucity of males, (ii) population 'overshoot' and (iii) pandemic disease. Extrinsic hypotheses include (iv) predation, (v) competition with fisheries concerns, (vi) interspecific competition, (vii) environmental change and (viii) human disturbance. Of the eight hypotheses proposed and examined here, we conclude that three can be discounted (i, v, viii), three are unlikely, but may require more testing (ii, iii, iv) and two are plausible (vi, vii). 3. The interspecific competition hypot hesis is difficult to test because it requires the simultaneous monitoring of species that overlap directly with elephant seals, many of which have not been identified or little is known. However, an analysis of the relationship between log variance and log abundance (Taylor's power law) for populations of southern and northern elephant seals suggests that interspecific competition is not a significant factor in the decline of the southern elephant seal. 4. The hypothesis that decreases in southern elephant se al populations between the 1950s and 1990s were caused by the environmental change is the easiest to test and most plausible of the hypotheses. We propose a framework by which to test this hypothesis to determine how food availability affects individual survival. 2005 Mammal Society. Article in Journal/Newspaper Elephant Seal Elephant Seals Heard Island Mirounga leonina Southern Elephant Seal Southern Ocean eCite UTAS (University of Tasmania) Argentina Heard Island Kerguelen Southern Ocean Mammal Review 35 1 82 100 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Oceanography Physical Oceanography |
spellingShingle |
Earth Sciences Oceanography Physical Oceanography McMahon, CR Bester, MN Burton, HR Hindell, MA Bradshaw, CJA Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina |
topic_facet |
Earth Sciences Oceanography Physical Oceanography |
description |
1. Between the 1950s and 1990s the southern elephant seal Mirounga leonina underwent large decreases in population size throughout most of its breeding range in the Southern Ocean. While current population estimates suggest a recent recovery, some breeding populations have continued to decrease in recent years (Macquarie and Marion Islands), others have either remained stable (South Georgia, Kerguelen and Heard Island) or have increased (Peninsula Valds, Argentina). 2. Intrinsi c hypotheses for patterns of regional decline include factors that are affected by density-dependent mechanisms: (i) paucity of males, (ii) population 'overshoot' and (iii) pandemic disease. Extrinsic hypotheses include (iv) predation, (v) competition with fisheries concerns, (vi) interspecific competition, (vii) environmental change and (viii) human disturbance. Of the eight hypotheses proposed and examined here, we conclude that three can be discounted (i, v, viii), three are unlikely, but may require more testing (ii, iii, iv) and two are plausible (vi, vii). 3. The interspecific competition hypot hesis is difficult to test because it requires the simultaneous monitoring of species that overlap directly with elephant seals, many of which have not been identified or little is known. However, an analysis of the relationship between log variance and log abundance (Taylor's power law) for populations of southern and northern elephant seals suggests that interspecific competition is not a significant factor in the decline of the southern elephant seal. 4. The hypothesis that decreases in southern elephant se al populations between the 1950s and 1990s were caused by the environmental change is the easiest to test and most plausible of the hypotheses. We propose a framework by which to test this hypothesis to determine how food availability affects individual survival. 2005 Mammal Society. |
format |
Article in Journal/Newspaper |
author |
McMahon, CR Bester, MN Burton, HR Hindell, MA Bradshaw, CJA |
author_facet |
McMahon, CR Bester, MN Burton, HR Hindell, MA Bradshaw, CJA |
author_sort |
McMahon, CR |
title |
Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina |
title_short |
Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina |
title_full |
Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina |
title_fullStr |
Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina |
title_full_unstemmed |
Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina |
title_sort |
population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal mirounga leonina |
publisher |
Blackwell Publishing Ltd |
publishDate |
2005 |
url |
https://doi.org/10.1111/j.1365-2907.2005.00055.x http://ecite.utas.edu.au/34661 |
geographic |
Argentina Heard Island Kerguelen Southern Ocean |
geographic_facet |
Argentina Heard Island Kerguelen Southern Ocean |
genre |
Elephant Seal Elephant Seals Heard Island Mirounga leonina Southern Elephant Seal Southern Ocean |
genre_facet |
Elephant Seal Elephant Seals Heard Island Mirounga leonina Southern Elephant Seal Southern Ocean |
op_relation |
http://dx.doi.org/10.1111/j.1365-2907.2005.00055.x McMahon, CR and Bester, MN and Burton, HR and Hindell, MA and Bradshaw, CJA, Population status, trends and a re-examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina , Mammal Review, 35, (1) pp. 82-100. ISSN 0305-1838 (2005) [Refereed Article] http://ecite.utas.edu.au/34661 |
op_doi |
https://doi.org/10.1111/j.1365-2907.2005.00055.x |
container_title |
Mammal Review |
container_volume |
35 |
container_issue |
1 |
container_start_page |
82 |
op_container_end_page |
100 |
_version_ |
1766400975623421952 |