Reproductive parameters of Bering‐Chukchi‐Beaufort Seas bowhead whales

Data from Bering-Chukchi-Beaufort Seas bowhead whales (Balaena mysticetus), harvested during 1973–2021 by aboriginal subsistence hunters, were used to estimate reproductive parameters: length at sexual maturity (LSM), age at sexual maturity (ASM), pregnancy rate (PR), and calving interval. Sexual ma...

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Bibliographic Details
Published in:Marine Mammal Science
Main Authors: George, John C Craig, Givens, Geof H, Horstmann, Lara, Suydam, Robert, Scheimreif, Kayla, Stimmelmayr, Raphaela, Sheffield, Gay, Sformo, Todd L, Person, Brian, Von Duyke, Andrew, Sousa, Leandra, Frantz, Rita M, Tarpley, Raymond
Format: Article in Journal/Newspaper
Language:unknown
Published: eScholarship, University of California 2024
Subjects:
Ecological Applications
Environmental Sciences
Women's Health
Reproductive health and childbirth
age at sexual maturity
Arctic
birth interval
bowhead whale
calving interval
fetus
length at sexual maturity
pregnancy rate
productivity
reproduction
Ecology
Evolutionary Biology
Zoology
Marine Biology & Hydrobiology
Balaena mysticetus
Chukchi
Online Access:https://escholarship.org/uc/item/051859tc
https://escholarship.org/content/qt051859tc/qt051859tc.pdf
https://doi.org/10.1111/mms.13079
Description
Summary:Data from Bering-Chukchi-Beaufort Seas bowhead whales (Balaena mysticetus), harvested during 1973–2021 by aboriginal subsistence hunters, were used to estimate reproductive parameters: length at sexual maturity (LSM), age at sexual maturity (ASM), pregnancy rate (PR), and calving interval. Sexual maturity (N=187 females) was determined from the presence/absence of corpora in the ovaries, or a fetus. Using sampling bias-corrected logistic regression, LSM was estimated at 13.5 m, 95% CI [13.0, 13.8]. There was a downward trend in LSM over time, statistically significant with one method but marginal with another. A growth model translated this estimate to an ASM estimate of 23.5 years, 95% CI [20.4, 26.7]. Pregnancy rate was determined from mature females (N=125), and from a subset limited to certain autumn-caught whales (n=37) to reduce bias. The PR was estimated at 0.46 globally, 95% CI [0.36, 0.55] and 0.38 for the autumn sample, 95% CI [0.20, 0.51]. Both estimated PRs are consistent with a 3-year calving interval, because the larger estimate includes two cohorts of pregnant whales harvested in spring, and bowhead whale gestation is longer than 12 months. These analyses represent the most conclusive empirical estimates of ASM, LSM, and PR for this bowhead whale stock from the largest available data sets to date.

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