Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada
Surveys to estimate walrus abundance at terrestrial haulout sites in the Penny Strait-Lancaster Sound (PS-LS) and West Jones Sound (WJS) stocks were conducted in 1977 and 1998-2009. The Minimum Counted Population (MCP) was similar in 1977 (565) to recent years (557) for the PS-LS stock. The MCP for...
Published in: | NAMMCO Scientific Publications |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Septentrio Academic Publishing
2014
|
Subjects: | |
Online Access: | https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608 https://doi.org/10.7557/3.2608 |
id |
ftunitroemsoe:oai:ojs.henry.ub.uit.no:article/2608 |
---|---|
record_format |
openpolar |
spelling |
ftunitroemsoe:oai:ojs.henry.ub.uit.no:article/2608 2023-05-15T17:06:31+02:00 Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada Stewart, Robert EA Born, Erik W Dunn, J Blair Koski, William R Ryan, Anna K 2014-12-15 application/pdf https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608 https://doi.org/10.7557/3.2608 eng eng Septentrio Academic Publishing https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608/5204 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608 doi:10.7557/3.2608 Copyright (c) 2014 Robert EA Stewart, Erik W Born, J Blair Dunn, William R Koski, Anna K Ryan http://creativecommons.org/licenses/by/3.0/ CC-BY NAMMCO Scientific Publications; Vol 9: Walrus of the North Atlantic; 95-122 2309-2491 1560-2206 10.7557/3.9 walrus Odobenus rosmarus abundance Canada surveys info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2014 ftunitroemsoe https://doi.org/10.7557/3.2608 https://doi.org/10.7557/3.9 2021-08-16T16:36:30Z Surveys to estimate walrus abundance at terrestrial haulout sites in the Penny Strait-Lancaster Sound (PS-LS) and West Jones Sound (WJS) stocks were conducted in 1977 and 1998-2009. The Minimum Counted Population (MCP) was similar in 1977 (565) to recent years (557) for the PS-LS stock. The MCP for the WJS stock was higher in recent surveys (404) than in 1977 (290). Regression analysis of MCP and density (number of walrus divided by number of haulouts surveyed) showed no significant trends over time. We also calculated bounded count estimates for comparison. Finally, we used broad-scale behavioural data to estimate the proportion of the total stock that could be considered countable, to produce two adjusted estimates. We selected recent surveys with good coverage and ignored adjusted estimates that were lower than MCP. For the PS-LS stock, the adjusted MCP (with 95% CL) was 672 (575-768) and 727 (623-831) walrus in 2007 and 2009, respectively. For WJS, the best estimates were the adjusted MCP of 503 (473-534) in 2008 and the adjusted bounded count of 470 (297-1732) in 2009. While both stocks appear to have remained stable over three decades, differences in survey coverage and possible differences in walrus distribution make precise population estimation difficult. Article in Journal/Newspaper Lancaster Sound Odobenus rosmarus walrus* University of Tromsø: Septentrio Academic Publishing Canada Jones Sound ENVELOPE(-86.000,-86.000,76.002,76.002) Lancaster Sound ENVELOPE(-83.999,-83.999,74.218,74.218) Penny Strait ENVELOPE(-97.002,-97.002,76.502,76.502) NAMMCO Scientific Publications 9 95 |
institution |
Open Polar |
collection |
University of Tromsø: Septentrio Academic Publishing |
op_collection_id |
ftunitroemsoe |
language |
English |
topic |
walrus Odobenus rosmarus abundance Canada surveys |
spellingShingle |
walrus Odobenus rosmarus abundance Canada surveys Stewart, Robert EA Born, Erik W Dunn, J Blair Koski, William R Ryan, Anna K Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada |
topic_facet |
walrus Odobenus rosmarus abundance Canada surveys |
description |
Surveys to estimate walrus abundance at terrestrial haulout sites in the Penny Strait-Lancaster Sound (PS-LS) and West Jones Sound (WJS) stocks were conducted in 1977 and 1998-2009. The Minimum Counted Population (MCP) was similar in 1977 (565) to recent years (557) for the PS-LS stock. The MCP for the WJS stock was higher in recent surveys (404) than in 1977 (290). Regression analysis of MCP and density (number of walrus divided by number of haulouts surveyed) showed no significant trends over time. We also calculated bounded count estimates for comparison. Finally, we used broad-scale behavioural data to estimate the proportion of the total stock that could be considered countable, to produce two adjusted estimates. We selected recent surveys with good coverage and ignored adjusted estimates that were lower than MCP. For the PS-LS stock, the adjusted MCP (with 95% CL) was 672 (575-768) and 727 (623-831) walrus in 2007 and 2009, respectively. For WJS, the best estimates were the adjusted MCP of 503 (473-534) in 2008 and the adjusted bounded count of 470 (297-1732) in 2009. While both stocks appear to have remained stable over three decades, differences in survey coverage and possible differences in walrus distribution make precise population estimation difficult. |
format |
Article in Journal/Newspaper |
author |
Stewart, Robert EA Born, Erik W Dunn, J Blair Koski, William R Ryan, Anna K |
author_facet |
Stewart, Robert EA Born, Erik W Dunn, J Blair Koski, William R Ryan, Anna K |
author_sort |
Stewart, Robert EA |
title |
Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada |
title_short |
Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada |
title_full |
Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada |
title_fullStr |
Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada |
title_full_unstemmed |
Use of Multiple Methods to Estimate Walrus (Odobenus rosmarus rosmarus) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada |
title_sort |
use of multiple methods to estimate walrus (odobenus rosmarus rosmarus) abundance in the penny strait-lancaster sound and west jones sound stocks, canada |
publisher |
Septentrio Academic Publishing |
publishDate |
2014 |
url |
https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608 https://doi.org/10.7557/3.2608 |
long_lat |
ENVELOPE(-86.000,-86.000,76.002,76.002) ENVELOPE(-83.999,-83.999,74.218,74.218) ENVELOPE(-97.002,-97.002,76.502,76.502) |
geographic |
Canada Jones Sound Lancaster Sound Penny Strait |
geographic_facet |
Canada Jones Sound Lancaster Sound Penny Strait |
genre |
Lancaster Sound Odobenus rosmarus walrus* |
genre_facet |
Lancaster Sound Odobenus rosmarus walrus* |
op_source |
NAMMCO Scientific Publications; Vol 9: Walrus of the North Atlantic; 95-122 2309-2491 1560-2206 10.7557/3.9 |
op_relation |
https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608/5204 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2608 doi:10.7557/3.2608 |
op_rights |
Copyright (c) 2014 Robert EA Stewart, Erik W Born, J Blair Dunn, William R Koski, Anna K Ryan http://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.7557/3.2608 https://doi.org/10.7557/3.9 |
container_title |
NAMMCO Scientific Publications |
container_volume |
9 |
container_start_page |
95 |
_version_ |
1766061675923898368 |