Spatial distribution and habitat preference of harbour seals (Phoca vitulina) in the Dutch North Sea

Abstract

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Top‐down pressure on a coastal ecosystem by harbor seals

“…This also seems to be reflected in the movement of seals that tend to forage further offshore during the winter (Aarts et al. ). In addition, also other sources of mortality (e.g., predation by cormorants or by‐catch in the shrimp fishery [Leopold et al.…”

Phylogenomic insights to the origin and spread of phocine distemper virus in European harbour seals in 1988 and 2002

“…Moreover, recent tagging and genetic studies indicate that especially juvenile harbour seals undertake movements across much greater distances than previously reported, and thus potentially could have played a larger role in transporting PDV longer distances. For instance, Wadden Sea harbour seals have been shown to undertake foraging trips of a couple of hundred kilometres into the North Sea (Dietz et al, 2013;Tougaard et al, 2008;Aarts et al, 2016), and recent population genetic analyses suggested movements among the seals in southern England, France and the Dutch Wadden Sea (Olsen et al, 2017). Likewise, tagging of harbour seals in the fall and early winter of 2016 provided the first documented movements from a haul-out in southern Kattegat to the central Limfjord (Rune Dietz and collaborators, unpublished) by an animal that has now been genetically determined to originate from the Limfjord (Morten Tange Olsen, unpublished).…”

“…It has been hypothesized that the unusual mass migration of harp seals in the winter and spring 1987/1988 lead to the introduction of the virus to the European harbour seals in 1988 (Haug & Nilssen, 1995;Nilssen et al, 1998), but the exact timing of these events have never been investigated, and a vector for the 2002 epidemic has not been proposed. Moreover, while the long-distance transmission events of PDV among harbour seal colonies was initially suggested to be aided by the less susceptible and more mobile grey seal (Haliocherus grypus) (Härkönen et al, 2006;McConnell et al, 1999) more recent tagging data indicate that while harbour seals are, in general, philopatric, individual seals occasionally undertake long-distance movements (Dietz et al, 2013;Reijnders et al, 2010;Tougaard et al 2008;Aarts et al, 2016). Therefore, dispersing harbour seals could have served as a vector for spreading the virus across Europe.…”

The Wozep Monitoring and Research Programme : an evaluation in light of research results and policy developments

“…The most promising improvement of these models, as recommended by the authors, would be a better representation of the effects of sediment and wind. Aarts et al (2016) show that harbour seal distribution in the Dutch North Sea is concentrated near the haul-out sites in the Wadden Sea and Southern Delta areas, with areas further offshore visited less frequently. This is partly a 'concentration effect' because all seals that use haul-out sites are concentrated in relatively small areas, and the paths between these and the foraging areas therefore have an extremely high abundance.…”