Title Capital expenditure and income (foraging) during pinniped lactation; the example of the Weddell Sea (Leptonychotes weddellii)
Author Eisert, R.; Oftedal, O.T.
Author Affil Eisert, R., Smithsonian Institution, National Zoological Park, Washington, DC. Other: Smithsonian Environmental Research Center
Source p.335-346, ; Smithsonian at the poles, Washington, DC, May 3-4, 2007, edited by I. Krupnik, M.A. Lang and S.E. Miller. Publisher: Smithsonian Institution Scholarly Press, Washington, DC, United States. ISBN: 978-0-9788460-1-50-9788460-1- X
Publication Date 2009
Notes In English. NSF grants ANT-0538592; Antarctic Conservation Act permit 2007-001. 138 refs. Ant. Acc. No: 86098
Index Terms Southern Ocean--Weddell Sea; behavior; Carnivora; Chordata; diet; ecology; Eutheria; feeding; habitat; International Polar Year 2007-08; IPY 2007-08 Research Publications; Mammalia; Pinnipedia; Southern Ocean; Tetrapoda; Theria; Vertebrata; Weddell Sea
Abstract Weddell seals, like many true seals (Phocidae), store nutrients in body tissues prior to lactation and then expend these "capital reserves" in pup rearing. During lactation, 40% or more of the initial mass of a lactating Weddell seal may be expended to cover the combined costs of maternal metabolism and milk production. However, most lactating Weddell seals also begin active diving to depths of 300 m or more by three to four weeks postpartum, and dietary biomarker data indicate that at least 70% of Weddell seals forage in late lactation. Thus, Weddell seals may employ a combined capital and income (foraging) strategy. Determining the relative importance of capital expenditures and food consumption to maternal reproduction will require accurate measurement of maternal energy expenditure, the magnitude of milk production, changes of maternal nutrient stores over lactation and the success of foraging efforts. Alternative scenarios include the following: (1) prey consumption is opportunistic rather than essential because body reserves of Weddell seals are sufficient for reproduction, (2) foraging is necessary only in those females (such as small or young seals) that have limited body stores relative to lactation costs, and (3) successful foraging is critical to the lactation strategy of this species. If alternative 2 or 3 is correct, the drops in pup production observed in Erebus Bay (McMurdo Sound, Ross Sea) during years of unusually heavy ice accumulation may reflect changes in foraging opportunities due to adverse impacts of heavy ice on primary production and on prey populations. Further study is needed on the effects of annual, cyclic, or long-term changes in prey abundance on Weddell seal reproduction.
URL http://hdl.handle.net/10088/6805
Publication Type monograph
Record ID 292158