Sam Ridgway; Michelle Reddy; Tricia Kamolnick; Deborah Skaar; Christine
Curry1
Calorie consumption, measured in weight of consumed food converted to
kilocalories (kcal), was tracked for 10 bottlenose dolphins (Tursiops truncatus) kept at
our San Diego, California facility. Five species of fish and one squid species were purchased in
lots and sampled for nutrient content by proximate analysis. Protein and fat content were
converted to kcal by figuring conservatively 9 kcal per g for fat and 4 kcal per g for protein.
Published values are higher, for example fat = 9.3 kcal; however, we know that digestive
efficiency of these nutrients in not 100% therefore we use the conservative values. Average
values in kcal/kg of food were as follows: Pacific mackerel =1130 (n = 37); Pacific herring =
1445 (n = 38); Columbia River Smelt = 1512 (n = 29); Squid = 692 (n = 6); capelin = 912 (n = 3)
and silver smelt = 903 (n = 9). Seven dolphins in our study were adults and three were immature
animals. Four pregnant females were charted 18 months before and continuing for 24 months after
parturition; data for offspring was tracked from the first fish consumed until the end of the
study. In one case, we tracked calorie consumption of a dolphin from her birth in 1979 until she
produced her own calf and successfully nursed it in 1991. Consumption did not increase
significantly during the first half of gestation, but slightly more calories were consumed
during the last half of gestation. In the 6 months following parturition, the cows consumed 129%
to 204% more (94-124 kcal/kg/da) than before they became pregnant. After weaning at two years of
age, young dolphins ate 60 to 120 kcal/kg/day. Mature, non-pregnant dolphins at relatively
constant body weight over periods of more than one year consumed between 30 and 60 kcal/kg/da.
For land mammals, basal metabolism is 70 X body wt0.75. On this basis, our average
200 kg adult non-pregnant dolphin needed only 3722 kcal/da for basal metabolic needs, but on
average consumed about 9000 kcal/da or 2.42 X predicted basal.