Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000

Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000

Annual abundance estimates of belugas, Delphinapterus leucas, in Cook Inlet were calculated from counts made by aerial observers and aerial video recordings. Whale group-size estimates were corrected for subsurface whales (availability bias) and whales that were at the surface but were missed (detection bias). Logistic regression was used to estimate the probability that entire groups were missed during the systematic surveys, and the results were used to calculate a correction to account for the whales in these missed groups (1.015, CV = 0.03 in 1994–98; 1.021, CV = 0.01 in 1999– 2000). Calculated abundances were 653 (CV = 0.43) in 1994, 491 (CV = 0.44) in 1995, 594 (CV = 0.28) in 1996, 440 (CV = 0.14) in 1997, 347 (CV = 0.29) in 1998, 367 (CV = 0.14) in 1999, and 435 (CV = 0.23, 95% CI=279–679) in 2000. For management purposes the current Nbest = 435 and Nmin = 360. These estimates replace preliminary estimates of 749 for 1994 and 357 for 1999. Monte Carlo simulations indicate a 47% probability that from June 1994 to June 1998 abundance of the Cook Inlet stock of belugas was depleted by 50%. The decline appears to have stopped in 1998.

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Main Authors: Hobbs, Roderick C., Rugh, David J., DeMaster, Douglas P.
Format: article biblioteca
Language:English
Published: 2000
Subjects:Biology, Ecology, Fisheries,
Online Access:http://hdl.handle.net/1834/26383
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spelling dig-aquadocs-1834-263832021-07-09T02:05:50Z Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000 Hobbs, Roderick C. Rugh, David J. DeMaster, Douglas P. Biology Ecology Fisheries Annual abundance estimates of belugas, Delphinapterus leucas, in Cook Inlet were calculated from counts made by aerial observers and aerial video recordings. Whale group-size estimates were corrected for subsurface whales (availability bias) and whales that were at the surface but were missed (detection bias). Logistic regression was used to estimate the probability that entire groups were missed during the systematic surveys, and the results were used to calculate a correction to account for the whales in these missed groups (1.015, CV = 0.03 in 1994–98; 1.021, CV = 0.01 in 1999– 2000). Calculated abundances were 653 (CV = 0.43) in 1994, 491 (CV = 0.44) in 1995, 594 (CV = 0.28) in 1996, 440 (CV = 0.14) in 1997, 347 (CV = 0.29) in 1998, 367 (CV = 0.14) in 1999, and 435 (CV = 0.23, 95% CI=279–679) in 2000. For management purposes the current Nbest = 435 and Nmin = 360. These estimates replace preliminary estimates of 749 for 1994 and 357 for 1999. Monte Carlo simulations indicate a 47% probability that from June 1994 to June 1998 abundance of the Cook Inlet stock of belugas was depleted by 50%. The decline appears to have stopped in 1998. 2021-06-24T16:25:43Z 2021-06-24T16:25:43Z 2000 article TRUE 0090-1830 http://hdl.handle.net/1834/26383 en http://spo.nwr.noaa.gov/mfr623/mfr6235.pdf application/pdf application/pdf 37-45 http://aquaticcommons.org/id/eprint/9769 403 2012-08-14 20:26:49 9769 United States National Marine Fisheries Service
institution UNESCO
collection DSpace
country Francia
countrycode FR
component Bibliográfico
access En linea
databasecode dig-aquadocs
tag biblioteca
region Europa del Oeste
libraryname Repositorio AQUADOCS
language English
topic Biology
Ecology
Fisheries
Biology
Ecology
Fisheries
spellingShingle Biology
Ecology
Fisheries
Biology
Ecology
Fisheries
Hobbs, Roderick C.
Rugh, David J.
DeMaster, Douglas P.
Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
description Annual abundance estimates of belugas, Delphinapterus leucas, in Cook Inlet were calculated from counts made by aerial observers and aerial video recordings. Whale group-size estimates were corrected for subsurface whales (availability bias) and whales that were at the surface but were missed (detection bias). Logistic regression was used to estimate the probability that entire groups were missed during the systematic surveys, and the results were used to calculate a correction to account for the whales in these missed groups (1.015, CV = 0.03 in 1994–98; 1.021, CV = 0.01 in 1999– 2000). Calculated abundances were 653 (CV = 0.43) in 1994, 491 (CV = 0.44) in 1995, 594 (CV = 0.28) in 1996, 440 (CV = 0.14) in 1997, 347 (CV = 0.29) in 1998, 367 (CV = 0.14) in 1999, and 435 (CV = 0.23, 95% CI=279–679) in 2000. For management purposes the current Nbest = 435 and Nmin = 360. These estimates replace preliminary estimates of 749 for 1994 and 357 for 1999. Monte Carlo simulations indicate a 47% probability that from June 1994 to June 1998 abundance of the Cook Inlet stock of belugas was depleted by 50%. The decline appears to have stopped in 1998.
format article
topic_facet Biology
Ecology
Fisheries
author Hobbs, Roderick C.
Rugh, David J.
DeMaster, Douglas P.
author_facet Hobbs, Roderick C.
Rugh, David J.
DeMaster, Douglas P.
author_sort Hobbs, Roderick C.
title Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
title_short Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
title_full Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
title_fullStr Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
title_full_unstemmed Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
title_sort abundance of belugas, delphinapterus leucas, in cook inlet, alaska, 1994–2000
publishDate 2000
url http://hdl.handle.net/1834/26383
work_keys_str_mv AT hobbsroderickc abundanceofbelugasdelphinapterusleucasincookinletalaska19942000
AT rughdavidj abundanceofbelugasdelphinapterusleucasincookinletalaska19942000
AT demasterdouglasp abundanceofbelugasdelphinapterusleucasincookinletalaska19942000
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