Steller sea lion research > Nutritional Stress >Energy Requirements > Measurements

Measuring Energy Expenditures

To understand the relationship between food intake and sea lion health, it is important to measure the costs associated with various activities, including swimming, resting metabolism, field metabolic rate, thermoregulation, and diving.

SWIMMING:
Changes in the type, location, or abundance of prey items available to Steller sea lions in the wild can have significant consequences on the amount of energy needed to catch them (and therefore how many they need to catch!).

Dr. David Rosen (UBC) measured the cost of swimming in a specially-designed swim mill (an aquatic treadmill). The captive sea lions are trained to swim against a current with a known velocity while their oxygen consumption (energy use) was measured.

Not only did scientists measure the cost of swimming at different speeds, but they also determined that Steller sea lions were as efficient swimmers as other marine mammals.

In another study, Lei Lani Stelle (UBC) measured the drag of sea lions to determine how body shape affects the amount of energy they need to swim.  The results of the experiment showed how their stream-lined shape reduced drag and swimming costs.

The cost and ability of sea lions to maneuver to catch their prey is also an important consideration. A study led by Olivier Chenval (UBC) examined the turning dynamics - forces generated during fast turning, of three captive Steller sea lions. The study also measured the amount of thrust and centripetal force generated during acceleration.

 

>>>Next: Thermoregulation

 

Swimming Related papers:

Rosen D. A. S., and A. W. Trites. 2002. Cost of transport in Steller sea lions, Eumetopias jubatus. Marine Mammal Science 18:513-524.

Stelle L. L., R. W. Blake, and A. W. Trites. 2000. Hydrodynamic drag in Steller sea lions (Eumetopias jubatus). Journal of Experimental Biology 203:1915-1923.