Pacific white-sided dolphins were once thought to be an open-ocean species. However since the 1980s their sightings in near-shore waters off of British Columbia have become increasingly common. One hypothesis for this shift in distribution is that the dolphins are responding to a change in prey availability. Knowing how much food dolphins require is integral to the conservation of this species and its habitat.
 
Erin Rechsteiner is discovering how much food Pacific white-sided dolphins require on the B.C. coast. A portion of her M.Sc. research is at the Vancouver Aquarium where she is measuring the resting metabolic rates of the three dolphins housed there. Resting metabolic rate is the basic number of calories that a dolphin requires for body maintenance.  For this study, dolphins are trained to rest quietly inside a floating metabolic dome where their rates of oxygen consumption can be measured. Pacific white-sided dolphins are generally known for their acrobatics and high activity levels in the wild, so training the animals to rest calmly in the metabolic dome was a 10-month challenge.

Photograph of a white-sided dolphin in the metabolic hood used to measure their resting metabolism (photo by Nicole Cann).

Erin's findings show that Pacific white-sided dolphins need a lot more calories to sustain basic body functions than previously thought. In fact, Pacific white-sided dolphins require 2.5-4.5 times the calories of terrestrial mammals.

Erin is integrating these measurements from the Vancouver Aquarium’s dolphins into a bioenergetics model to account for other energetic costs (i.e., activity, digestion, gestation, lactation and growth). Preliminary results from her model indicate that Pacific white-sided dolphins requires a lot of calories in the wild—about 5 times what a similar-sized human would require.

Erin Rechsteiner is a Masters student at U.B.C.