Spring haul-out behavior of ringed seals (Pusa hispida) in Kongsfjorden, Svalbard

TLDR: Investigation of the spring molting period of 2003 in Kongsfjorden, Svalbard, Norway found that time of day and date significantly affected the number of ringed seals hauled out on the ice surface, and adult females had the greatest number of haul-out periods that exceeded 24 h.

Abstract: Haul-out behavior of ringed seals (Pusa hispida) was investigated during the spring molting period of 2003 (May‐July) in Kongsfjorden, Svalbard, Norway. Hourly counts were conducted on the land-fast ice in six spatially defined sectors in the inner fjord, from an elevated land-based vantage point from early May through until the ice began to break up in June, from 0600 to 2200 daily (total counts n = 478). Concomitantly, measurements were made of a variety of weather parameters. Multiple regression analyses revealed that time of day (P < 0.001) and date (P < 0.001) significantly affected the number of ringed seals hauled out on the ice surface. Other factors influencing the number of seals counted on the ice were air temperature (P = 0.011) and wind speed (P < 0.001). Daily peaks occurred in the early afternoon between 1300 and 1400 and the seasonal high (n = 385) was registered during the first week in June, after which the number of seals on the ice in the fjord declined. In addition to the visual counts, 24 ringed seals were equipped with VHF transmitters, and the haul-out behavior of individuals was monitored from May through July via an automatic recording station. The VHF-tagged seals exhibited the same diurnal pattern seen in the total counts, with haul-out most frequent from 1300 to 1400. Pups exhibited short and frequent haul-outs, whereas longer haul-out periods were seen in the older age classes; adult females had the greatest number of haul-out periods that exceeded 24 h. The seasonal peak of haul-out for the tagged seals preceded the peak seasonal counts by approximately 3 wk. This may reflect significant out- and influx of seals from and to the area, a phenomenon warranting further attention because of its implications for assessment studies.