Optimal foraging experiments on captive Steller sea lions: a feasibility study
Downloadable Video Clips
The following AVI video-clips are best downloaded and viewed in sequence:
Clip 1: Attachment of recorder baseplate (18" 8.56 MB AVI)
Under full gas anesthesia (the anesthesia is done for purposes other than our foraging study), we glue a recorder baseplate to the dorsal fur of a Steller sea lion using 5-minute epoxy.
Clip 2: Attachment of recorder and setup of fish-feeder tubes in sea lion habitat tank (22" 8.83 MB AVI)
A sea lion is trained to target while a data recorder is attached to the baseplate via a quick-release mechanism. This data recorder logs swimspeed and dive depth. In the Steller sea lion habitat at the Alaska SeaLife Center, three fish feeder tubes are lowered into the water. The tubes are about six meters long. They have a trap door at the lower end, which is operated by a handle at the top end. Food fish are dropped into these feeder tubes, and can be released at given times by opening the trap doors. We use a variety of prey fish in our experiments, including pollock, mackerel, cod and sandlance. Each feeder tube is operated by one of the interns on the project: Megan, Lisa and Melissa.
Clip 3: Experimental setup (19" 5.72 MB AVI)
Once the fish feeder tubes are prepared, and a sea lion has been instrumented with a recorder and entered the habitat tank, the experimental session is conducted by Texas A&M PhD candidate Leslie Cornick from a control station in front of the large underwater viewing window into the habitat. Here Leslie can view the images of four separate control cameras on a video monitor, while the images are also recorded for subsequent analysis. From her control station Leslie can operate the light targets mounted at the trap door end of the feeder tubes. These light targets are used mostly for training purposes, and to elicit different swim patterns and dive durations in the sea lions. Monica - an intern on this project - takes detailed notes for each session.
Clip 4: Optimal foraging experimental session (40" 9.63 MB AVI)
During the feeding sessions, different types of dives are simulated by making the sea lion swim different distances before the first prey release, and by varying the prey release rate. Giving-up-time (return to the surface) and swimspeed are amongst the variables recorded for subsequent analysis.
Clip 5: Free-feeding session with Sandlance fish (23" 7.78 MB AVI)
For some feeding sessions, large amounts of sandlance - a small prey fish - are thrown into the Steller sea lion habitat tank.
Clip 6: Complete segment consisting of clips one through 5 (3' 66 MB AVI)
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