SLiDAP: The Satellite-Linked Data Acquisition and Photogrammetry System.

Validation and Assessment of Seasonal and Individual Steller Sea Lion Body Condition and Population Trends.

The specific hypotheses we will test within the scope of the biological application of the SLiDAP system are listed here as null-hypotheses.

Null-hypotheses:

1. There is no regional difference in lipid mobilization during fasting.
   Unlike phocid seals, lipid depots are comparably sparse and are not distributed evenly throughout the body of otariid seals. Instead, there are regions that tend to have a greater percentage of the total lipid stored, such as the neck region. As a result, we expect selective mobilization of energy stores from larger lipid depots, either as a function of absolute energy availability or perhaps to maintain a critical threshold of blubber for insulatory purposes at more vulnerable sites of the body. If a significant site-specific selective mobilization is detected, this will have important implications for the accurate estimation of body mass and body condition using morphometric parameters and 3D photogrammetry.
   
   
2. T here is no selective fatty acid mobilization during fasting.
   Blubber tissue can be analysed for its constituent fatty acids, which can be a reflection of the diet of the animal. However, in this instance, blubber fatty acids can also be used as a measure of selective lipid mobilization or preferential fatty acid removal from the blubber layer for energetic purposes during times of negative energy balance. Using fatty acid analysis at several sites of the body during an experimental fast, we will be able to determine regional differences, or a lack thereof, in fatty acid metabolism. This study will further allow an examination of potential physiological implications of selective fatty acid depletion for a nutritionally challenged individual. We will determine the accuracy of body condition predicted from body mass and total body water, estimated by three-dimensional photogrammetry using a combination of isotope dilution, BIA and blubber-scan methods for reference.
   
   
3. Longitudinal and cross-sectional body mass values obtained in the rookeries observed via the SLIDAP systems do not exhibit significant seasonal variation.
   
   
4. Longitudinal and cross-sectional body condition does not exhibit significant seasonal variation.
   
   
5. (set) Body mass and body condition trends (if observed) are not related to reported prey biomass removal values and other environmental parameters.
   
   
6. There is no seasonal variation in numbers of individuals hauled out, as observed via the SLIDAP systems.
   
   
7. There is no seasonal variation in the distribution of age classes present in monitored sites.

© M. Horning & J. Mellish 1999, 2000, 2001.

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