Kiska tests telemetry
ASLC Photo
The western population of Alaska’s Steller sea lions crashed by more than 75 percent in the 1980s and has so far failed to rebound, despite an ocean that teems with gobs of fish for them to eat.
Something has gone askew in the sea lion diet. But what? How does one uncover the jaw-popping details of sea lion foraging, something that occurs at acrobatic high-speed below the waves? How do you penetrate a moment hidden from the prying eyes of biologist and fisherman alike? What really goes on when sea lion mouth meets sea lion lunch?
The scientific team at the Alaska SeaLife Center has found a way.
With the cooperation of Kiska, one of the center’s captive female sea lions, biologist Russ Andrews and a scientific team have been developing sensors that could eventually unlock details of how wild sea lions snatch and then swallow live fish in the ocean off Alaska’s coast.
Alaska SeaLife Research Education Coordinator Brendan Smith writes in a fact sheet about the research:
ASLC scientists have been recording Kiska’s movements and how wide she opens her jaw to capture fish—markers that can be detected with camera equipment have been attached to her jaw line. Telemetry devices have also been attached to her head and back to measure and record her acceleration in the water. Lastly, a stomach temperature pill is being tested to determine the change in stomach temperature from the time of prey ingestion until fish are completely digested.
It is likely that when Kiska ingests the cold fish, her stomach temperature will initially decrease, but as her body begins to metabolically breakdown and digest the fish, her stomach temperature will increase gradually until normal. The time it takes to reach normal stomach temperature (37 °C) is a reflection of the fish’s mass. The stomach temperature pill, when coupled with measuring dive depth and duration, will provide a good indication of exactly when and where wild sea lions are foraging in the water column.
Kiska snatches a fish
ASLC
The work with Kiska illustrates how miniature tracking technology and tiny computers have changed marine mammal research forever, letting scientists gather detailed information from environments beyond the reach of human scrutiny. By attaching the devices to sea lion hide, or by implanting a temperature recording device in their bellies, the scientists can directly tackle fundamental questions about ecology and foraging.