Bioenergetics model for estimating food requirements of female Pacific walruses (Odobenus rosmarus divergens)

Marine Ecology Progress Series
By: , and 



Pacific walruses Odobenus rosmarus divergens use sea ice as a platform for resting, nursing, and accessing extensive benthic foraging grounds. The extent of summer sea ice in the Chukchi Sea has decreased substantially in recent decades, causing walruses to alter habitat use and activity patterns which could affect their energy requirements. We developed a bioenergetics model to estimate caloric demand of female walruses, accounting for maintenance, growth, activity (active in-water and hauled-out resting), molt, and reproductive costs. Estimates for non-reproductive females 0–12 yr old (65−810 kg) ranged from 16359 to 68960 kcal d−1 (74−257 kcal d−1 kg−1) for years with readily available sea ice for which we assumed animals spent 83% of their time in water. This translated into the energy content of 3200–5960 clams per day, equivalent to 7–8% and 14–9% of body mass per day for 5–12 and 2–4 yr olds, respectively. Estimated consumption rates of 12 yr old females were minimally affected by pregnancy, but lactation had a large impact, increasing consumption rates to 15% of body mass per day. Increasing the proportion of time in water to 93%, as might happen if walruses were required to spend more time foraging during ice-free periods, increased daily caloric demand by 6–7% for non-lactating females. We provide the first bioenergetics-based estimates of energy requirements for walruses and a first step towards establishing bioenergetic linkages between demography and prey requirements that can ultimately be used in predicting this population’s response to environmental change.
Publication type Article
Publication Subtype Journal Article
Title Bioenergetics model for estimating food requirements of female Pacific walruses (Odobenus rosmarus divergens)
Series title Marine Ecology Progress Series
DOI 10.3354/meps09706
Volume 460
Year Published 2012
Language English
Publisher Inter-Research
Publisher location Oldendorf/Luhe, Germany
Contributing office(s) Alaska Science Center
Description 15 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Marine Ecology Progress Series
First page 261
Last page 275
Google Analytic Metrics Metrics page
Additional publication details