Concentrations of electrolytes, hormones, and other constituents in fresh postmortem blood and urine of fin whales (Balaenoptera physalus)

Abstract

Concentrations of various blood and urine constituents were measured on postmortem samples from 286 fin whales (Balaenoptera physalus) caught off Iceland during the summers of 1981–1989. Measurements were carried out on both serum and urine from 21 whales so that results could be compared. The mean serum urea concentration in fin whales was similar to that in odontocetes but 5 times higher than in domesticated terrestrial mammals. Serum triglyceride concentrations were twice as high as in fasting man and showed no diurnal peaks. Serum cortisol concentrations were about 2 times lower than in domestic mammals and showed neither diurnal variation nor a significant correlation with chase time (time from sighting until killing). Serum aldosterone concentrations were similar to those in bottlenose dolphins and, as expected, showed a negative correlation with urinary Na+concentration. Blood thyroxine levels correlated significantly (p < 0.003) with chase time. Mean urinary potassium concentrations were 6 times higher than average seawater levels, while sodium and chloride levels were about 2–3 times higher than in humans but never as high as those in seawater. Urinary magnesium levels were 4–5 times higher than in domestic animals but less than half those in seawater. Average urine osmolality was higher than in seawater.