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 (<i>Pusa hispida</i>) 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.