Development and testing of remote assessment
of body composition of Steller sea lions via bio-electric-impedance telemetry,
combined with 3D-photogrammetric body volume estimates
In this study of the Laboratory
for Applied Biotelemetry & Biotechnology, WFSC M.Sc. student Jason Waite
is testing whether three-dimensional photogrammetry can be used as a tool to
estimate body mass via body-volume measurements, as obtained from multiple time-synchronous
digital still pictures of juvenile Steller sea lions. Jason is furthermore testing
the validity of bio-electric-impedance measurements as a correlate of lean body
mass. The combination of these two techniques will allow us to obtain a body
condition index, which should reflect the nutritional status of an animal. The
goal of our study is to develop techniques that will ultimately allow us to
assess body condition in free-ranging animals, via remote imaging in Steller
rookeries, combined with bio-impedance telemetry.
[D]
To the right, you can see a lateral view of Woody, a six-year
old male Steller sea lion at the Alaska
Sea Life Center, alternating with a 3D wire frame model reconstructed from
four separate digital still images, taken at the same instance but from different
angles, using Photomodeler
Pro 3.0 software (EOS
Inc.). Using this wire frame model, Jason calculates the volume of Woody.
Jason is testing to see how well volume figures for different Stellers relate
to body mass. As seen in this image, Woody is carrying a Bioelectric-Resistance-Recorder
(BRR). The BRR unit continually records electrical resistance values measured
between two or four electrodes glued to the skin of the sea lion. This procedure
is similar to a technology now available for home use in bathroom scales. Bioelectric
Impedance Analysis (BIA) relates electrical properties of tissue such as Impedance,
Reactance, Resistance and Conductance, to lean tissue mass. In our trials we
are merely recording resistance values.
View 3-D Steller sea lion models:
You can download and view three-dimensional models, providing
your browser is VRML enabled (Virtual Reality Modeling Language). To test whether
your browser is VRML enabled, go to the Web-3D
VRML Browser detector website by the NIST. This site will tell you whether
your browser is VRML enabled, and will suggest compatible VRML plugins and link
you to free downloads. With a 3-D enabled browser, you can rotate the 3-D wire-frame
models, zoom in and out, and look at the models from any angle.
3-D model of Sugar: [D]
Click
on the thumbnail to the left to take a closer look at a three-dimensional wire
frame model of Sugar, a six-year old female Steller sea lion at the Alaska Sea
Life Center (56 Kb WRL file). The model was assembled with Photomodeler
Pro 3.0 Software.
Texture-mapped 3-D model
of Woody: [D]
Click on the thumbnail to the left to see a texture-mapped 3-D model of Woody,
a six-year old male Steller sea lion (78 Kb WRL file, plus 237 Kb of JPEG texture
image files). As explained above, Woody is carrying a Bioelectric-Resistance-Recorder
in these texture-mapping images.
More information on Photogrammetry and Steller
sea lions:
Take a look at the FASEB
Experimental Biology 2000 conference poster Jason presented in San Diego
(257 Kb pdf file).
Check out the 3-D Photogrammetry page in our Technology
section under Analytical Approaches for further details.
More
about Stellers
The
NMML/NMFS Steller page
ADF&G's
Steller sea lion page
Sponsored by:
Principal Investigator:
Co-investigators:
- Jason Waite, Randall Davis.
Collaborator:
This project
/ work is being / was carried out under one or more of these permits:
TAMU ULACC AUP# 9-170, 9-171, 2001-112
ASLC IACUC AUP# 00-004, 00-006, 01-001
MMPA permit # 881-1443 to the ASLC
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