Recovering a device the size of a hand-held microphone from the open waters of the Pacific is no small feat, nor a routine task for TOPP shark taggers. "They lose container ships out there!" noted Stanford PhD student Kevin Weng, whose dripping long-handled net had scooped up what was surely the catch of the day. Weng and his team had launched an unusual retrieval mission into ugly seas, riding up and down on white-capped swells off Point Arguello in Santa Barbara County.
Time was of the essence. PAT tags are designed to blast transmit their data to receivers aboard polar-orbiting satellites using batteries that last 10-12 days to ensure that the most complete data set possible is captured. And even under the best of circumstances, what is captured is actually just a summary of the data. If researchers must act within a narrow window of transmission time if they hope to snag the little device and its rich cargo of raw data, sensor readings that include time, depth and temperature.
TOPP scientists rarely collect PAT tags, which are designed to be used when recovery is difficult or impossible. But this tag was special. At stake was the precious information-cache collected by a small, but world-famous white shark; the first to thrive in captivity. Never before had so many people been so interested in where an individual traveled after leaving the aquarium.
Using a special directional antenna, the team successfully located the tag's radio signal, which led the boat right to their prize, and in short order, the tag was in the net and the data was in Weng's computer. "I downloaded it before we got back, he explained. "I couldn't wait."
Back at the Block lab, the team generated a map of the young shark's month long journey away from Monterey. The temperature and depth data, which appear consistent with young white shark behavior TOPP researchers have already documented, will advance the efforts of aquarium and TOPP scientists to learn more about this mysterious resident of the open ocean. -- Diane Richards