Haul-out behaviour of Arctic ringed seals (Pusa hispida): inter-annual patterns and impacts of current environmental change

Abstract

Hauling out onto a solid substrate is an integral part of most pinnipeds’ activity budgets. Ringed seals (Pusa hispida) are an Arctic species that hauls out on sea ice routinely throughout the year. In 2006, a sudden change in the sea-ice regime occurred in Svalbard (Norway). Amongst other changes, the amount of land-fast ice declined sharply. This study examined the intra- and inter-annual haul-out behaviour of 60 ringed seals equipped with Satellite Relay Data Loggers before [2002–2003 (n = 22)] and after [2010–2012 (n = 38)] the sea-ice decline occurred. In total, ringed seals hauled out 5–20% of the time (between August and May) with a mean haul-out duration of 3.3 h. The mean interval between haul-out events was 36 h, with a seasonal pattern that peaked in October (max 81 days). Haul-out probability was influenced by wind speed, temperature and solar hour to varying extents seasonally. After the sea-ice decline, intervals between haul-out events were significantly longer, and from December to March seals had shorter haul-out durations and hauled out a smaller proportion of the time. Haul-out probabilities in the winter and spring were more heavily influenced by weather conditions in 2010–2012 compared to 2002–2003, especially on the west coast where sea-ice declines have been greatest. These changes are likely due to ringed seals hauling out less often in snow lairs due to inadequate snow and ice conditions. Ringed seal haul-out behaviour will likely continue to be impacted negatively by ongoing environmental change, with concomitant impacts on their activity/energy budget and polar bears’ hunting behaviour.