Abstract:
Mammalian reproduction is metabolically regulated; therefore, the endangered
status and high variability in reproduction of North Atlantic right whales Eubalaena glacialis
necessitate accurate assessments at sea of the nutritional condition of living individuals. Aerial
photogrammetry was used to measure dorsal body width at multiple locations along the bodies of
free-swimming right whales at different stages of the female reproductive cycle (E. glacialis) and
during the initial months of lactation (mother and calf Eubalaena australis) to quantify changes in
nutritional condition during energetically demanding events. Principal components analyses indicated
that body width was most variable at 60% of the body length from the snout. Thoracic,
abdominal and caudal body width of E. australis thinned significantly during the initial months of
lactation, especially at 60% of body length from the snout, while their calves’ widths and widthto-
length ratios increased. The body shape of E. glacialis that had been lactating for 8 mo was significantly
thinner than non-lactating, non-pregnant E. glacialis. Body shape of E. glacialis measured
in the eighth month of lactation was significantly thinner than that of E. australis in the first
month, but did not differ from that of E. australis in the third and fourth months. Body width was
comparable with diameter calculated from girth of carcasses. These results indicate that mother
right whales rely on endogenous nutrient reserves to support the considerable energy expenditure
during the initial months of lactation; therefore, photogrammetric measurements of body
width, particularly at 60% of body length from the snout, are an effective way to quantitatively
and remotely assess nutritional condition of living right whales.
