Indices of body condition and body composition in female Antarctic fur seals (Arctocephalus gazella)

An attempt was made to develop simple, inexpensive, rapid means of determining body composition in Antarctic fur seals (Arctocephalus gazella). Measurements of total body water (TBW) and total body lipid (TBL), obtained by hydrogen isotope dilution, were compared to the results of bioelectrical impedance analysis (BIA) and morphometric indices of body condition in 52 adult females. TBW was weakly correlated with BIA measurements of resistance (r = -0.30, P < 0.03). Conductor volume (length2/resistance) was more highly correlated with TBW (r = 0.75, P < 0.0001) and the inclusion of mass into the predictive equation improved the correlation further (r = 0.95, P < 0.0001). A body condition index (mass/length) previously used in pinniped studies was positively correlated to TBL (r = 0.77, P < 0.0001) validating its use as a relative index of condition. However, body mass alone was highly correlated to TBW (r = 0.94, P < 0.0001) and appears to provide a simple, rapid means of estimating body composition in adult females. This technique may also be applicable to juvenile male Antarctic fur seals.