It is crucial to examine the genetic diversity and structure of small, isolated populations, especially those at the edge of their distribution range, because they are vulnerable to stochastic processes if genetic diversity is low and the isolation level is high, and because such populations provide insight into the consequences of population declines in a broader conservation context. The harbour seal (Phoca vitulina) population in Svalbard is the world's northernmost P. vitulina population. Nothing is known about the genetic diversity, distinctiveness, or origin of this small, marginalized mammalian population. Thus, the present study investigated its genetic status in the context of nearby P. vitulina in Iceland, south‐east Greenland, and northern Norway: this species is depleted/threatened in all of these regions. A total of 174 samples distributed between the four locations were analysed using 15 polymorphic microsatellites and variation in the displacement loop region (D‐loop). Each of the four locations was a genetically distinct population. The Svalbard population was highly genetically distinct, had reduced genetic diversity, received limited gene flow, had a rather low effective population size, and showed an indication of having experienced a bottleneck resulting from a recent population decline. The significant heterozygote excess observed in the Svalbard sample might be attributed to the low effective population size, which could initiate future population inbreeding effects. This phenomenon has not been reported earlier from other P. vitulina populations, but if the Svalbard population is experiencing inbreeding, this could reduce its resilience to climate change, disease outbreaks, or other perturbations. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 420–439.

Abstract1. In the United Kingdom (UK), several harbour seal (Phoca vitulina) populations have been declining over the past decade. In order to understand the effect of these changes in abundance, this study seeks to determine the population structure of harbour seals in the UK, and in Scotland in particular, on a wider and finer spatial scale than has previously been reported.2. Harbour seals were genotyped from 18 different localities throughout the UK and neighbouring localities in mainland Europe, at 12 microsatellite loci. Results from Bayesian and frequency based tests of population structure suggested an initial structural division into two main groups consisting of localities in northern UK and southern UK-mainland Europe, respectively.3. These two clusters were further divided into four geographically distinct genetic clusters.4. An overall agreement between the genetic results and the existing management areas for UK harbour seals was observed, but it is also clear that an adaptive management approach should be adopted, in which the delineation of the current management areas is maintained until further genetic and ecological information has been accumulated and analysed.

The harbour seal (Phoca vitulina) is the most widely distributed pinniped, occupying a wide variety of habitats and climatic zones across the Northern Hemisphere. Intriguingly, the harbour seal is also one of the most philopatric seals, raising questions as to how it colonized its current range. To shed light on the origin, remarkable range expansion, population structure and genetic diversity of this species, we used genotyping‐by‐sequencing to analyse ~13,500 biallelic single nucleotide polymorphisms from 286 individuals sampled from 22 localities across the species’ range. Our results point to a Northeast Pacific origin of the harbour seal, colonization of the North Atlantic via the Canadian Arctic, and subsequent stepping‐stone range expansions across the North Atlantic from North America to Europe, accompanied by a successive loss of genetic diversity. Our analyses further revealed a deep divergence between modern North Pacific and North Atlantic harbour seals, with finer‐scale genetic structure at regional and local scales consistent with strong philopatry. The study provides new insights into the harbour seal's remarkable ability to colonize and adapt to a wide range of habitats. Furthermore, it has implications for current harbour seal subspecies delineations and highlights the need for international and national red lists and management plans to ensure the protection of genetically and demographically isolated populations.

Investigations of hooded seals Cystophora cristata have revealed high prevalences of Brucella-positive seals in the reduced Northeast Atlantic stock, compared to the increasing Northwest Atlantic stock. This study evaluated the relation between Brucella-serostatus in seals in the Northeast Atlantic stock and age, sex, body condition and reproduction. Bacteriology documented which animals and organs were B. pinnipedialis positive. No relationship was observed between Brucella-serostatus and body condition or reproductive traits. Pups (<1 mo old) had a substantially lower probability of being seropositive (4/159, 2.5%) than yearlings (6/17, 35.3%), suggesting that exposure may occur post-weaning, during the first year of life. For seals >1 yr old, the mean probability of being seropositive decreased with age, with no seropositives older than 5 yr, indicating loss of antibody titre with either chronicity or clearance of infection. The latter explanation seems to be most likely as B. pinnipedialis has never been isolated from a hooded seal >18 mo old, which is consistent with findings in this study; B. pinnipedialis was isolated from the retropharyngeal lymph node in 1 seropositive yearling (1/21, 5%). We hypothesize that this serological and bacteriological pattern is due to environmental exposure to B. pinnipedialis early in life, with a subsequent clearance of infection. This raises the question of a reservoir of B. pinnipedialis in the hooded seal food web.KEY WORDS: Pinniped · Pups · Brucellosis · Serostatus · Bacteriology · Infection clearance · Atlantic hooded seal stock · Food web Resale or republication not permitted without written consent of the publisherDis Aquat Org 106: [187][188][189][190][191][192][193][194][195][196] 2013 Greenland (NWS) (Andersen et al. 2009) and the Nordic Seas (Greenland, Norwegian and Icelandic Seas, NES) (Folkow et al. 1996(Folkow et al. , 2010.While estimates of abundance in the NWS have increased since the 1980s (Hammill & Stenson 2006), abundance of the NES appears to have decreased to only 10 to 15% of the 1946 population size, from 575 000 hooded seals in 1946 to approximately 85 000 hooded seals in 2011, and has remained stable at this low level since the 1980s (ICES 2011). Hooded seal hunts in the West Ice have been conducted since the 18th century, and after 1920 the hunt was of a significant extent. In 1958, agreements were made between Norway and the Soviet Union on time and activity restrictions on the hooded seal hunt in the West Ice, but it was not until 1971 that quotas were introduced (Bjørge 2010). The introduction of quotas did not alter the negative population development in the NES, and due to the decline of the NES, no commercial hunt has been conducted on the NES since 2007 (ICES 2011), and the hooded seal species has been classified since 2008 as 'Vulnerable' in the Red List of Threatened Species of the International Union for Conservation of Nature (IUCN) (Kovacs 2008).Brucella spp. were first isolated from marine mammals in 1994 (Ross et al....

Identifying the processes that drive changes in the abundance and distribution of natural populations is a central theme in ecology and evolution. Many species of marine mammals have experienced dramatic changes in abundance and distribution due to climatic fluctuations and anthropogenic impacts. However, thanks to conservation efforts, some of these species have shown remarkable population recovery and are now recolonizing their former ranges. Here, we use zooarchaeological, demographic and genetic data to examine processes of colonization, local extinction and recolonization of the two northern European grey seal subspecies inhabiting the Baltic Sea and North Sea. The zooarchaeological and genetic data suggest that the two subspecies diverged shortly after the formation of the Baltic Sea approximately 4200 years bp, probably through a gradual shift to different breeding habitats and phenologies. By comparing genetic data from 19th century pre-extinction material with that from seals currently recolonizing their past range, we observed a marked spatiotemporal shift in subspecies boundaries, with increasing encroachment of North Sea seals on areas previously occupied by the Baltic Sea subspecies. Further, both demographic and genetic data indicate that the two subspecies have begun to overlap geographically and are hybridizing in a narrow contact zone. Our findings provide new insights into the processes of colonization, extinction and recolonization and have important implications for the management of grey seals across northern Europe.