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

Hobbs, Roderick C. and Rugh, David J. and DeMaster, Douglas P. (2000) Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000. Marine Fisheries Review, 62(3), pp. 37-45.

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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.

Item Type: Article
Title: Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000
Personal Creator/Author:
Hobbs, Roderick C.
Rugh, David J.
DeMaster, Douglas P.
Refereed: Yes
Journal or Publication Title: Marine Fisheries Review
Volume: 62
Number: 3
Page Range: pp. 37-45
Date: 2000
ISSN: 0090-1830
Issuing Agency: United States National Marine Fisheries Service
Subjects: Biology
Item ID: 9769
Depositing User: Patti M. Marraro
Date Deposited: 14 Aug 2012 20:26
Last Modified: 14 Aug 2012 20:26
URI: http://aquaticcommons.org/id/eprint/9769

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