Population assessment of Western Gray Whales in 2006
A population assessment of the western gray whale (Eschrichtius robustus) was conducted using the Photo-identification data collected off Sakhalin Island under the joint Russia-U.S. program from 1994 to 2005. This is an update of the assessment by Reeves et al (2005) which used data up to 2003, fitt...
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ftunivnebraskali:oai:digitalcommons.unl.edu:usdeptcommercepub-1066 2023-11-12T04:25:29+01:00 Population assessment of Western Gray Whales in 2006 Cooke, Justin G. Weller, David W. Bradford, Amanda L. Burdin, Alexander M. Brownell, Robert L., Jr. 2006-06-01T07:00:00Z application/pdf https://digitalcommons.unl.edu/usdeptcommercepub/71 https://digitalcommons.unl.edu/context/usdeptcommercepub/article/1066/viewcontent/Brownell_2006_Population_assessment.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/usdeptcommercepub/71 https://digitalcommons.unl.edu/context/usdeptcommercepub/article/1066/viewcontent/Brownell_2006_Population_assessment.pdf Publications, Agencies and Staff of the U.S. Department of Commerce Environmental Sciences text 2006 ftunivnebraskali 2023-10-30T09:43:02Z A population assessment of the western gray whale (Eschrichtius robustus) was conducted using the Photo-identification data collected off Sakhalin Island under the joint Russia-U.S. program from 1994 to 2005. This is an update of the assessment by Reeves et al (2005) which used data up to 2003, fitted to the same, individually-based population model. New median estimates of key population parameters (with 90% Bayesian confidence intervals) are 0.986 (0.975 - 0.995) for the adult survival rate; 0.72 (0.60 - 0.83) for the survival rate from calf to yearling; 3.0% per annum (2.1% – 4.2%) for the average annual rate of population increase over 1994-2005; 0.43 (0.37 - 0.50) for the female sex ratio and 122 whales (113 - 131) for the 1+ (non-calf) population size in 2006. The updated assessment is more optimistic than the Reeves et al assessment. This is mainly due to reduced calving intervals observed in recent years, implying a higher reproductive rate. The modal calving interval has shortened from 3 years to 2 years in the most recent seasons, which is consistent with reduced disturbance from industrial activity during 2002-04. Forward projections of the population model to 2030, assuming no additional mortality or disturbance to reproduction, indicate a high probability (>99%) of population increase. Three whales (all female) were killed in fishing nets on the coast of Japan in 2005 during the northward migration. Projections of the female population incorporating extra mortality at the 2005 level indicate a high probability (~75%) of population decline and a substantial risk (>25%) of extirpation by 2030. It is important to avoid any further human-caused deaths in this depleted population. Text Sakhalin University of Nebraska-Lincoln: DigitalCommons@UNL Reeves ENVELOPE(-67.983,-67.983,-67.133,-67.133) |
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Open Polar |
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University of Nebraska-Lincoln: DigitalCommons@UNL |
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ftunivnebraskali |
language |
unknown |
topic |
Environmental Sciences |
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Environmental Sciences Cooke, Justin G. Weller, David W. Bradford, Amanda L. Burdin, Alexander M. Brownell, Robert L., Jr. Population assessment of Western Gray Whales in 2006 |
topic_facet |
Environmental Sciences |
description |
A population assessment of the western gray whale (Eschrichtius robustus) was conducted using the Photo-identification data collected off Sakhalin Island under the joint Russia-U.S. program from 1994 to 2005. This is an update of the assessment by Reeves et al (2005) which used data up to 2003, fitted to the same, individually-based population model. New median estimates of key population parameters (with 90% Bayesian confidence intervals) are 0.986 (0.975 - 0.995) for the adult survival rate; 0.72 (0.60 - 0.83) for the survival rate from calf to yearling; 3.0% per annum (2.1% – 4.2%) for the average annual rate of population increase over 1994-2005; 0.43 (0.37 - 0.50) for the female sex ratio and 122 whales (113 - 131) for the 1+ (non-calf) population size in 2006. The updated assessment is more optimistic than the Reeves et al assessment. This is mainly due to reduced calving intervals observed in recent years, implying a higher reproductive rate. The modal calving interval has shortened from 3 years to 2 years in the most recent seasons, which is consistent with reduced disturbance from industrial activity during 2002-04. Forward projections of the population model to 2030, assuming no additional mortality or disturbance to reproduction, indicate a high probability (>99%) of population increase. Three whales (all female) were killed in fishing nets on the coast of Japan in 2005 during the northward migration. Projections of the female population incorporating extra mortality at the 2005 level indicate a high probability (~75%) of population decline and a substantial risk (>25%) of extirpation by 2030. It is important to avoid any further human-caused deaths in this depleted population. |
format |
Text |
author |
Cooke, Justin G. Weller, David W. Bradford, Amanda L. Burdin, Alexander M. Brownell, Robert L., Jr. |
author_facet |
Cooke, Justin G. Weller, David W. Bradford, Amanda L. Burdin, Alexander M. Brownell, Robert L., Jr. |
author_sort |
Cooke, Justin G. |
title |
Population assessment of Western Gray Whales in 2006 |
title_short |
Population assessment of Western Gray Whales in 2006 |
title_full |
Population assessment of Western Gray Whales in 2006 |
title_fullStr |
Population assessment of Western Gray Whales in 2006 |
title_full_unstemmed |
Population assessment of Western Gray Whales in 2006 |
title_sort |
population assessment of western gray whales in 2006 |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
2006 |
url |
https://digitalcommons.unl.edu/usdeptcommercepub/71 https://digitalcommons.unl.edu/context/usdeptcommercepub/article/1066/viewcontent/Brownell_2006_Population_assessment.pdf |
long_lat |
ENVELOPE(-67.983,-67.983,-67.133,-67.133) |
geographic |
Reeves |
geographic_facet |
Reeves |
genre |
Sakhalin |
genre_facet |
Sakhalin |
op_source |
Publications, Agencies and Staff of the U.S. Department of Commerce |
op_relation |
https://digitalcommons.unl.edu/usdeptcommercepub/71 https://digitalcommons.unl.edu/context/usdeptcommercepub/article/1066/viewcontent/Brownell_2006_Population_assessment.pdf |
_version_ |
1782339680493109248 |