The latest additions to the Vancouver Aquarium Marine Science Centre family only arrived in mid August, but already they're helping shed light on the habits and physiology of their species.

The five female Steller sea lion pups came from the Scott Islands, off the northern tip of Vancouver Island, earlier this summer. Nuka, Yasha, Eden, Tasu and Boni spent a few weeks under close scientific and medical scrutiny at the Animal Care Centre at the University of British Columbia before moving to their permanent home at the Aquarium.

The population to which the new pups belong is relatively healthy. But their Alaskan counterparts were added to the U.S. endangered species list in 1997. The North Pacific population has shrunk by more than 70 percent over the last two decades and biologists are unsure why. A major area of research is now focusing on nutritional stress associated with changes in the ocean ecosystem and, consequently, available diet. To that end, the pups will play important roles in studies of sea lion energy consumption patterns, growth and metabolism. They join four adult sea lions familiar to Aquarium staff and biologists with the North Pacific Universities Marine Mammal Research Consortium, increasing the sample size of the feeding and bioenergetics studies.

Even before they moved to the Aquarium, the pups provided novel insight into how newborn sea lions, which nurse for nine months or more before learning to feed for themselves, respond to the day-long periods they must go without nursing. "We need to know how they compensate and how much energy they're burning while mother is foraging and unavailable to nurse," says Dr. David Rosen, a veteran sea lion researcher.

The first task for the Aquarium staff is to familiarize the pups with research equipment before they get too old, and too large. At the moment, each weighs between 30 and 40 kg -- comparable to a large German shepherd - and most of that comes in the form of muscle. "They don't look too big, but they're heavy and low to the ground, and difficult to move when they don't want to," notes Rosen. Of course, it only gets more problematic as they grow older. By the end of their first years, they should top 120 kg, reaching 350 kg or more by full maturity.

The changes in energy demands, which fish provide the most nutritious diet and how fast the sea lions grow should supply valuable data that may help scientists explain the species' decline and give conservation managers a chance to develop successful recovery plans.

August 2001