Thermoregulation and energetics of fin and sei whales based on postmortem, stratified temperature measurements

Abstract

It has been postulated that large whales have uniform body temperatures and may experience heat stress in warm waters or when active in colder water. Postmortem (approximately 15 min), stratified body-core temperature measurements of fin and sei whales (Balaenoptera physalus, B. borealis), taken from the commercial catch allocated to the Icelandic fleet, revealed low, mid-core temperatures, which further decreased towards the blubber. This arrangement is considered in terms of reduced thermal maintenance costs and therefore food requirements. The temperature elevation that had been anticipated following intensive pursuit was not evident, a phenomenon that might be explained by propulsive efficiency (a function of internal mechanical design or external hydrodynamic characteristics) and (or) a high thermoregulatory capacity.