USE OF SATELLITE-LINKED TELEMETRY TO STUDY STELLER SEA LION AND NORTHERN FUR-SEAL FORAGING

One explanation for recent declines in some Alaskan pinniped populatio ns is that ecosystem changes may have reduced the availability of pref erred prey. Part of our evaluation of this hypothesis involves the use of satellite-linked telemetry to study Steller sea lion (Eumetopias j ubatus) and northern fur seal (Callorhinus ursinus) foraging. Data on dives (depth and duration) and water temperatures arc collected by sat ellite-linked time-depth recorders (SLTDR) glued to the backs of sea l ions and fur seals. These data are then summarized and stored for late r transmission. Data are relayed back to land through NOAA Tiros-serie s satellites and are processed by Service-Argos (a U.S.-French consort ium). These transmissions are also used to calculate at-sea and on-lan d locations of the animals through use of Doppler shifts of the freque ncy of received transmissions. Ultimately, diving and temperature can be reconciled with at-sea locations to compare foraging areas with loc ations of known prey stocks.