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Latitudinal Distribution, Calf Growth and Metabolsim, and Reproductive Energetics of Gray Whales, Eschrichtius Robustus

出版	Oregon State University, 1988
URL	http://books.google.com.hk/books?id=rcHHnQEACAAJ&hl=&source=gbs_api

註釋Gray whales accomplish an annual migration which spans as much as 50° of latitude in the northeast Pacific Ocean. This migration links their summer high latitude feeding grounds with winter calving and breeding areas. The purpose of this study was to determine how adult females apportion their stored lipid reserves while away from their principal feeding areas to accommodate their own maintenance and locomotory needs while developing a fetus and transferring energy through lactation to support growth and maintenance of their calves. Major components of this study included examinations of migratory swimming speeds and costs of transport, of calf growth and mortality rates, of metabolic and heat loss rates, of summer distribution patterns, and of the magnitudes and utilization rates of maternal lipid reserves. The results of this study support the conclusions of other investigations that calf heat losses are similar to minimum observed metabolic rates, and that maintenance and lactation costs can be accommodated without winter feeding by all but the small adult females. It is suggested that present oceanographic conditions in the North Pacific Ocean support a larger gray whale population and allow very different gray whale feeding and migrating patterns than existed during the last glacial maximum.