ICE‐BASED CENSUS OF BOWHEAD WHALES MIGRATING PAST POINT BARROW, ALASKA, 1978‐1983

A bstract Bowhead whale ( Balaena mysticetus ) census data obtained during the northward spring migration are summarized for 1978–1983. Population size estimates are derived from counts made by observers standing on the seaward edge of shorefast ice in the vicinity of Point Barrow, Alaska, from mid‐...

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Bibliographic Details
Published in:Marine Mammal Science
Main Authors: Krogman, Bruce, Rugh, David, Sonntag, Ronald, Zeh, Judith, Ko, Daijin
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 1989
Subjects:
Aquatic Science
Ecology, Evolution, Behavior and Systematics
Balaena mysticetus
Barrow
bowhead whale
Point Barrow
Alaska
Online Access:http://dx.doi.org/10.1111/j.1748-7692.1989.tb00327.x
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1748-7692.1989.tb00327.x
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1748-7692.1989.tb00327.x
Description
Summary:A bstract Bowhead whale ( Balaena mysticetus ) census data obtained during the northward spring migration are summarized for 1978–1983. Population size estimates are derived from counts made by observers standing on the seaward edge of shorefast ice in the vicinity of Point Barrow, Alaska, from mid‐April to early June. The research design utilized two counting stations: South Perch, the primary counting station, and North Perch, used to determine the number of whales missed by South Perch observers. The percentage missed is estimated for each visibility category and used here to correct the census counts. Each season's population estimate is calculated as the sum of the number of trials of several independent multinomial distributions representing different visibility conditions. Corrections are applied for unwatched hours and hours with inferior visibility. A mean estimate of the number of whales passing within view of the census station was computed as 3,674 ± 299. This estimate was based on data collected in 1978, 1981, 1982, and 1983, years with the least apparent biases. Aerial survey data provide estimates of the proportion of whales passing at various distances seaward of the census sites as follows: 0.58 from the ice edge to 2 km, 0.76 to 3 km, and 0.80 to 4 km. Correcting for whales too far offshore to be seen by the ice‐based observers results in a population estimate of over 4,200 bowheads.

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