Research Background

In 1993, a large scale research plan was developed by the North Pacific Universities Marine Mammal Research Consortium to study marine mammal and fishery interactions in the North Pacific, and to determine possible causes for declining populations of Steller sea lions.

A combination of field, captive and laboratory studies make up the components of the research undertaken. Various hypotheses such as increases in parasites or disease, predation by killer whales, environmental dangers or disasters and nutritional stress, caused by natural or human interference in amounts, quality or distribution of their prey, are all being studied as potential factors in the diminishing number of sea lions. Research to analyse the nutritional stress hypothesis is fronted with the help of the Vancouver Aquarium Marine Science Centre's Marine Mammal Department.

Steller Sea Lion Research at the Vancouver Aquarium Marine Science Centre

A steller sea lion on a rock

Only a concerted effort and a commitment to long-term research will determine the causes of changes in the North Pacific. Field, captive, and laboratory studies are integrated and draw on the expertise and talents of university-based physiologists, ecologists, marine mammalogists, fisheries specialists and oceanographers. Since 1993, the Consortium has been engaged in a captive research program at the Aquarium to better understand the nutritional needs of Steller sea lions, and to develop better techniques for studying them in the wild.

In 1993, five Steller sea lion pups were brought to the Aquarium from a remote rookery off the northern tip of Vancouver Island. Another was obtained in 1994 when a female pup was found orphaned. They were brought to the Aquarium to participate in this vital research project — one that may save their species from possible extinction. A second group of four Steller sea lions were brought into the Aquarium in 1997 to replace the initial animals that were being transferred to other research institutions as part of an effort to establish an international research effort. Another five pups arrived in the fall of 2000. The pups have been participating in a comprehensive research study designed to explore the "nutritional stress" hypothesis, the leading contender to explain the decline in Steller sea lions in the wild. This hypothesis proposes that Steller sea lions are declining due to a change in the type, quantity, or distribution of their prey. The studies are providing information that is otherwise unobtainable from wild animals.

Analysis of Steller Sea Lions at the Aquarium

With the help of the Aquarium’s captive sea lions, important advances were made in several areas, including:

1. energy requirements of Steller sea lions
2. the relationship of diet to sea lion health
3. nutritional requirements and the value of different diets such as pollock and herring
4. validating methods of studying sea lions in the wild

All components are helping to test the nutritional stress hypothesis, by applying the results to wild populations