Studying northern fur seals in the laboratory

To help investigate the reasons for the recent declines in northern fur seals, Consortium researchers led by Dr. David Rosen (UBC) are conducting studies with 6 female fur seals at the Marine Mammal Energetics and Nutrition Laboratory at the Vancouver Aquarium. The fur seals were transported from St Paul Island just after they weaned, but before they disappeared into the ocean for their extraordinary 2-year at-sea voyage. Studying these animals in the laboratory affords researchers an opportunity that cannot be obtained with wild animals.

To understand what is happening to these animals in the wild, scientists are conducting a number of studies that are aimed at addressing basic research questions about northern fur seals:

How much fish do northern fur seals require?
• We are recording baseline measures of growth, resting metabolism, and daily energy expenditures in young northern fur seals. These measures will enhance bioenergetic models that predict energy and food requirements.

• We are determining the ability of northern fur seals to function in different water temperatures. This will provide information on the cost of living in different ocean environments, and shed light on the potential role of water temperatures on defining fur seal distribution.

• We are determining the species-specific calibration coefficients (enrichment values) needed to determine diet from fatty acid signature analysis. These studies will assist scientists to determine the type of food that wild fur seals are eating, and evaluate the potential link between diet and population changes.

Are young northern fur seals limited in their foraging capacity?
• We are documenting the development of oxygen stores and muscle structure in post-weaning northern fur seals. These data can be used to calculate the physiological limitations to foraging, particularly for young animals.

• We are estimating the maximum food intake levels of young northern fur seals. The results of this study are used to understand how fur seals regulate their food intake, and to establish realistic physiological limits for foraging model

What are the effects of prey disruption on their physiology?
• We are determining the fasting capabilities of young fur seals and its interaction with thermal demands. These studies reveal the capacity for fur seals to undergo periodic fasts, including whether such episodes curtail their ability to remain warm.

• We are examining the effect of nutritional stress on energy balance in young northern fur seals: changes in metabolism, body composition, blood biochemistry and haematology, stomach temperature, and surface heat loss. Such measures provide both a better understanding of the physiological consequences of such episodes, but also allow researchers to develop accurate measures of nutritional stress for wild animals.

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