Haul-out activity of ringed seals (Phoca hispida) determined from satellite telemetry

The haul-out activity of 15 ringed seals (Phoca hispida) equipped with satellite-linked radio transmitters was studied in NW Greenland (ca, 73degrees- 78degreesN). Between 19 June 1997 and 30 June 1999, telemetry data on haul-out activity were obtained by the "Land-Sea-Reporter " (LSR), "Time-at-Depth" (TAD), and "Timelines" (TIM) systems housed within the satellite transmitters, The haul-out activity (% of total time hauled out) reported by the TIM system, which is specifically designed for collecting haul-out data, was about 1.4 times higher than that inferred from the LSR, but only about 0.7 of that inferred from TAD data. The TIM were used to describe haul-out activity. A total of 1,011 d with TIM were obtained (64.5% of a total of 1,568 "seal-days" monitored) representing data from nearly an entire annual cycle. No differences were found in percentage of time hauled out per month among various age categories. At all seasons the haul-out time showed considerable individual variation. There were no trends in percentage of time hauled out per month during late summer, fall, and winter (August-February). During the High Arctic winter darkness (November-January) the percentage of haul-out per month ranged between 3,9% in an adult (SD = 2.44, range: 1.1%-5.7%, n = 3 mo) and 15.7%; in a subadult (SD = 1.95, range: 13.7%-17.6%, n = 3 mo). From late March there was a significant increase in haul-out time. Between 1 and 30 June, when aerial surveys of basking ringed seals usually are conducted, the haul-out time (% per day) increased from about 25% to about 57%. No tendencies in diel haul-out activity were revealed.