Extreme moulting site fidelity of the Saimaa ringed seal

Abstract

Site fidelity is commonly observed in pinnipeds and has direct consequences for individual space use and population dynamics. Here, we used photo-identification recapture data to quantify site fidelity of the endangered Saimaa ringed seal (Pusa hispida saimensis) over four successive moulting seasons. We identified 337 seals based on their permanent fur patterns, and 192 of them were observed during at least 2 years. Over the study period, the median number of terrestrial haul-out sites used by an individual seal was four, and nearly 50% of the seals reused them over the years. Although eight seals performed movements (up to 48 km) between the different water basins of Lake Saimaa, most of the studied seals remained in the same water basin over the years. The median distance between successive moulting sites used by an individual seal was 643 m. While these distances were similar within years in both sexes, the distances between years were longer in females, suggesting post-nursing related behaviour. The extreme site fidelity of the Saimaa ringed seal has important implications for its conservation, especially in the land use management of the Lake Saimaa shoreline.

Molting phenology of a lacustrine ringed seal, Pusa hispida saimensis

“…Recently, because Saimaa ringed seals can be identified from their unique pelage patterns (Koivuniemi et al, 2016), photo-ID approach has also been proposed as an alternative method, as mild winters are hampering the lair censuses (Koivuniemi et al, 2016(Koivuniemi et al, , 2019. Saimaa ringed seals exhibit a high degree of site fidelity to their molting sites (e.g., Biard et al, 2022), which are easily accessible to people by boats and, along with the growing trend of nature tourism, seal watching has been increasing. Boats and other anthropogenic activities may cause disturbance (Niemi et al, 2013), which in turn may prolong molting time and incur energetic costs for the seals (see Paterson et al, 2012), but their long-term consequences are difficult to estimate without proper understanding of the phenology of the molt and general haul-out behavior.…”

High levels of inbreeding with spatial and host‐associated structure in lice of an endangered freshwater seal

“…Kim, 1975; Leonardi et al, 2013). However, close seal‐to‐seal encounters also occur during the early‐summer moulting period, when two or more seals can share resting sites on large lakeside rocks (Biard et al, 2022). Recent observations also indicate that multiple seals can co‐inhabit the same resting lairs that the seals dig into lakeside snowdrifts during winter (M. Kunnasranta, personal observation), so these may provide additional opportunities for louse transmission.…”

“…Kim, 1975;Leonardi et al, 2013). However, close seal-to-seal encounters also occur during the early-summer moulting period, when two or more seals can share resting sites on large lakeside rocks (Biard et al, 2022).…”

Developing artificial nest boxes for a large aquatic mammal

“…Hepp & Kennamer, 1992). The high degree of site fidelity (Biard et al, 2022) and especially natal philopatry of female Saimaa ringed seals (Valtonen et al, 2012) are likely to increase the occupancy rate of nest boxes in locations where lairs have been observed in consecutive years over randomly selected locations. Spatial behavioural patterns of the seals should be taken into consideration when planning nest box placement with the purpose of increasing overall usage.…”