The dynamics of grey seals (Halichoerus grypus) off Amrum in the south-eastern North Sea — evidence of an open population

Abt, Kai; Hoyer, Nils; Koch, Lothar; Adelung, D.

doi:10.1016/s1385-1101(01)00094-6

Cited by 15 publications

(9 citation statements)

References 17 publications

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“…In our study such long distance movements between distinct haulout sites were not observed in all tracked grey seals, with twelve of thirty-four individuals tracked from MOL remaining within 50 km of their capture site during the whole tracking period, often including the breeding season. This highlights the large variability in individual movement patterns (Thompson et al 1993) as well as the high degree of site fidelity, at least seasonally (Abt et al 2002, Karlsson et al 2005, Oksanen et al 2012.…”

Section: Distribution and Connectivitymentioning

confidence: 96%

“…Strong breeding site fidelity in adult grey seals would explain genetic differentiation between colonies, despite extensive movements of individuals outside the breeding season (Allen et al 1995). Although philopatry would be the general rule for female and male grey seals (Pomeroy et al 1994, Pomeroy et al 2000, immigration from colonies in the UK outside the breeding season was suggested to explain the rapid increase in grey seal numbers in Germany (Abt et al 2002). Density-dependent effects may lead to the establishment of new breeding colonies, as observed in the North Sea (Gaggiotti et al 2002).…”

Section: Distribution and Connectivitymentioning

confidence: 99%

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Grey and harbour seals in France: Distribution at sea, connectivity and trends in abundance at haulout sites

Vincent

Huon

Caurant

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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Grey (Halichoerus grypus) and harbour seals (Phoca vitulina) are sympatric seal species, but they display distinct strategies of habitat use and connectivity between haulout sites. The distribution patterns and variations in relative abundance of both species were investigated along the French coast of the English Channel, at the southern limit of their range where seal numbers are increasing. Regular censuses conducted at all main haulout sites in mainland France showed significant seasonal variations at most sites, with more harbour seals counted during summer (breeding and moulting seasons), and more grey seals during summer only in the eastern English Channel. Trends in maximum haulout numbers at haulout sites showed a significant increase over the last five years, ranging from 9.7 to 30.9% per year for harbour seals, and from 5.8% (in the western English Channel) to 49.2% (in the eastern English Channel) per year for grey seals. These rates of increase in grey seal numbers are not linked to local pup production and most probably result from seal movements from the southwest British Isles and the North Sea, respectively. Aerial surveys conducted across the English Channel showed that most seal observations at sea were concentrated in the northeastern English Channel. Telemetry showed that the 28 harbour seals tracked remained highly coastal, within a radius of 100km from their haulout sites, and did not move to other known colonies. Grey seals moved much greater distances, reaching up to 1200 km from their capture site. More than half of the 45 grey seals tracked crossed the English Channel, especially during the breeding season, moving to known colonies in the southwest British Isles and the North Sea. Combining individual tracks and long-term surveys of the seal populations allowed a better understanding of the dynamics of these populations and their connectivity at a larger regional scale. The findings provide direct information for the management of grey and harbour seals within the frame of the Marine Strategy Framework Directive, and highlight focus areas where potential interactions between the two species should be monitored.

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Section: Distribution and Connectivitymentioning

confidence: 96%

Section: Distribution and Connectivitymentioning

confidence: 99%

Grey and harbour seals in France: Distribution at sea, connectivity and trends in abundance at haulout sites

Vincent

Huon

Caurant

et al. 2017

Deep Sea Research Part II: Topical Studies in Oceanography

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“…Until 2001, the number of harbor seals increased again to approximately 20,000 individuals in the Wadden Sea. Grey seals could be found in numbers from 50 to 100 in the same area (3). Between May 2002 and February 2003, a new epidemic occurred in the North and Baltic seas, again associated with the occurrence of phocine distemper virus (11).…”

mentioning

confidence: 92%

Identification and Molecular Characterization of Beta-Hemolytic Streptococci Isolated from Harbor Seals ( Phoca vitulina ) and Grey Seals ( Halichoerus grypus ) of the German North and Baltic Seas

Vossen

Abdulmawjood²,

Lämmler³

et al. 2004

J Clin Microbiol

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Bacteriological investigations of seals of the German North and Baltic seas resulted in the isolation of bacteria of the genus Streptococcus belonging to Lancefield's serological groups C, F, and L. According to biochemical, serological, and 16S ribosomal DNA analysis, the group C and group F streptococci were identified as Streptococcus phocae. The group L streptococci could be classified as Streptococcus dysgalactiae subsp. dysgalactiae

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“…Grey seals had been extinct in the Wadden Sea area (south-eastern North Sea) for centuries. Some 25 years ago, grey seals started to re-establish in a few colonies off the German island of Amrum and in the western part of the Dutch Wadden Sea (Reijnders et al, 1995;Abt et al, 2002). Most probably, the animals originated from the eastern UK, mainly the Farne Islands where grey seals are abundant.…”

Section: Grey Sealmentioning

confidence: 99%

Marine Mammals

2015

Offshore Sea Life ID Guide

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The dynamics of grey seals (Halichoerus grypus) off Amrum in the south-eastern North Sea — evidence of an open population

Cited by 15 publications

References 17 publications

Grey and harbour seals in France: Distribution at sea, connectivity and trends in abundance at haulout sites

Grey and harbour seals in France: Distribution at sea, connectivity and trends in abundance at haulout sites

Identification and Molecular Characterization of Beta-Hemolytic Streptococci Isolated from Harbor Seals ( Phoca vitulina ) and Grey Seals ( Halichoerus grypus ) of the German North and Baltic Seas

Marine Mammals

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