Harbour seal Phoca vitulina movement patterns in the high-Arctic archipelago of Svalbard, Norway

Abstract

Harbour seals Phoca vitulina are mainly considered a temperate species, but the world's northernmost population resides year-round in the high-Arctic archipelago of Svalbard. In this study we document post-moulting at-sea movements of 30 individuals from this population using satellite relay data loggers deployed in the autumns of 2009 and 2010. All of the seals showed a strong preference for the west side of the archipelago, staying mainly in coastal areas (< 50 km over the continental shelf), but seldom entering the fjord systems. Distance swam per day, individual home range size, and trip duration increased throughout the winter to a peak that was reached when drifting sea ice in the region was at a maximum. No effect of age was observed, but sex differences were significant; males occupied larger areas than females. Habitat selection was quantified by modelling time spent in area (TSA) as a function of environmental parameters using Cox proportional hazard models (CPH). The harbour seals avoided heavy ice concentrations (> 50%) but did occupy areas with substantial amounts of drifting ice (5 to 25%). Shallow water (<100 m) and steep bathymetric slopes were preferred to deep water or flat-bottom areas. Harbour seal distribution in Svalbard is largely restricted to coastal areas that are heavily influenced by Atlantic water brought northward in the West Spitsbergen Current; both the temperature and influx of this water type are predicted to increase in the future. It is thus likely that environmental conditions in Svalbard in the future will become more favourable for harbour seals.

Making it through the first year: Ontogeny of movement and diving behavior in harbor seals from Svalbard, Norway

“…Most pups stayed in the vicinity of their natal area on the WSS, which is an area that is also occupied year‐around by the adult seals in this population (Blanchet et al . ).…”

“…Adults in the Svalbard population also follow this pattern, staying within 200 km of PKF (Blanchet et al . ).…”

“…But, it is noteworthy that the 30 d home‐range size of pups is generally smaller than the 30 d home‐range size found for adults throughout the year (Blanchet et al . ) suggesting that pups's at‐sea movements remain somewhat different from those of adults throughout the first year of life. Most pups stayed in the vicinity of their natal area on the WSS, which is an area that is also occupied year‐around by the adult seals in this population (Blanchet et al .…”

“…The R2s for the entire tracks were also calculated for each adult in a broader study of this population, as a comparison although these data are not presented here (see Blanchet et al . , for details on the adult harbor seals from this population).…”

Climate change impacts on wildlife in a High Arctic archipelago – Svalbard, Norway

“…For Svalbard's isolated harbour seal Phoca vitulina population (Andersen et al ., ), a warmer climate with reduced sea ice is likely to result in a broader distribution and increasing population size. Currently, harbour seals in Svalbard avoid areas with dense ice concentrations (Blanchet et al ., ) and mainly occupy the west coast of Svalbard where warm Atlantic water dominates (Blanchet et al ., , ). It is expected that these harbour seals will increase their distributional area including expanding their pupping range in the coming years, a development that satellite telemetry tracking data suggests is already ongoing (Hamilton et al ., ).…”