scholarly journals Movements and site fidelity of harbour seals (Phoca vitulina) in Kattegat, Denmark, with implications for the epidemiology of the phocine distemper virus

2012 ◽  
Vol 70 (1) ◽  
pp. 186-195 ◽  
Author(s):  
Rune Dietz ◽  
Jonas Teilmann ◽  
Signe M. Andersen ◽  
Frank Rigét ◽  
Morten T. Olsen
Keyword(s):  
Gene Flow ◽  
Home Range ◽  
West Coast ◽  
Site Fidelity ◽  
Phoca Vitulina ◽  
Swedish West Coast ◽  
Phocine Distemper Virus ◽  
Harbour Seals ◽  
Limited Gene Flow ◽  
Satellite Tagging

Abstract Dietz, R., Teilmann, J., Andersen S. M. Rigét, F., and Olsen, M. T. 2013. Movements and site fidelity of harbour seals (Phoca vitulina) in Kattegat, Denmark, with implications for the epidemiology of the phocine distemper virus. – ICES Journal of Marine Science, 70:186–195. Twenty-seven harbour seals were caught and tagged at the island of Anholt in central Kattegat, Denmark, the epicentre of the phocine distemper virus (PDV) outbreaks in 1988 and 2002 that killed 50–60% of the populations. The satellite tagging shows that harbour seals from Anholt moved widely across Kattegat with a maximum distance of 249 km from the tagging haul-out site. Overall, females travelled over a wider area compared with males [90% kernel home range (KHR) females, 5189 km2; males, 3293 km2). KHR calculated for yearlings (6414 km2) is larger than for subadults (2534 km2), which again is larger than for adult seals (1713 km2), showing a strong site fidelity, indicating limited gene flow between haul-out sites. Distances moved and home range sizes increased across autumn, peaked in February–March, and decreased through spring. During the breeding season in spring, all seals were very stationary around Anholt. The onset of the PDV epizootics in 1988 and 2002 took place when the Anholt harbour seals congregate on the Island during April. Anholt seal were also documented to have contact with infected seal locations at Hesselø, Læsø, and the Swedish west coast, although this contact takes place during winter prior to the documented summer outbreaks.

Spatial structure of harbour seal populations and the implications thereof

2001 ◽  
Vol 79 (12) ◽  
pp. 2115-2127 ◽  
Author(s):  
T Härkönen ◽  
K C Harding
Keyword(s):  
Population Dynamics ◽  
Site Fidelity ◽  
Phoca Vitulina ◽  
Population Increase ◽  
Dynamic Processes ◽  
Term Study ◽  
Long Term Study ◽  
Harbour Seals ◽  
Age And Sex

A long-term study of freeze-branded harbour seals (Phoca vitulina) revealed explicit site fidelity. Individuals were followed up to 14 years of age and none of the 163 branded animals were observed to haul out beyond a 32-km distance from the site where they were branded as pups. Within this range, striking spatial segregation by age and sex prevailed. While females' site fidelity increased with age, males spent less time at their natal site with increasing age. These findings have consequences for understanding the population dynamics of harbour seals, since single "colonies" will act as partly isolated "subpopulations" in some contexts but not in others. The differing migration tendencies of the population segments lead to spatially segregated sex and age ratios of subpopulations and create a complex pattern of connectivity among these subpopulations. Ignoring the spatial scale will lead to severe misinterpretations of analyses of basic population-dynamic processes, especially rates of population increase, rates of gene flow, and the dynamics of the spread of diseases. We suggest that when studies have different aims, these should be addressed by encompassing different numbers of subpopulations.

scholarly journals Status of harbour seals (Phoca vitulina) in mainland Norway

2010 ◽  
Vol 8 ◽  
pp. 61 ◽  
Author(s):  
Kjell Tormod Nilssen ◽  
Nils-Erik Skavberg ◽  
Michael Poltermann ◽  
Tore Haug ◽  
Tero Härkönen ◽  
...  
Keyword(s):  
Tidal Cycle ◽  
Lower Estimate ◽  
Phoca Vitulina ◽  
Aerial Photo ◽  
Norwegian Coast ◽  
Phocine Distemper Virus ◽  
Harbour Seals ◽  
Minimum Estimate ◽  
Almost All

Harbour seals were counted along the entire Norwegian coast at known moulting haulout sites in the period mid-August to early September 2003-2006. In 2003-2005, almost all known moulting areas from Finnmark to Vestfold counties were covered by aerial photo surveys flown at altitudes of approximately 800-900 ft (243-274m), and at low tide (± 2 hours). Surveys in the Østfold County were flown in 2003-2006 at 300 ft (91m), and the small tidal amplitudes permitted counts to be carried out irrespective of the tidal cycle. In some sub-areas, two or three independent surveys were conducted. Visual counts using binoculars from smaller boats and islands were carried out in some selected areas. The surveys revealed a total minimum population of 6,705 harbour seals in Norwegian waters. Harbour seals were most abundant in the Nordland and Sør-Trøndelag counties with minimum estimates of approximately 2,500 and 1,500 seals, respectively. The presented minimum estimate is approximately 800 seals lower than an estimate obtained in a comparable study carried out during the moult in 1996-1999. Increased anthropogenic removals, and the phocine distemper virus (PDV) epidemic in the Skagerrak region in 2002, may have contributed to the current lower estimate.

Display-area size, tenure length, and site fidelity in the aquatically mating male harbour seal, Phoca vitulina

2000 ◽  
Vol 78 (12) ◽  
pp. 2209-2217 ◽  
Author(s):  
Sofie M Van Parijs ◽  
Vincent M Janik ◽  
Paul M Thompson
Keyword(s):  
Comparative Analysis ◽  
Site Fidelity ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Small Scale ◽  
Mating Season ◽  
Display Area ◽  
Harbour Seals ◽  
Acoustic Array ◽  
Number Of Males

Previous studies of the distribution and activity of male harbour seals, Phoca vitulina, based on telemetric techniques have shown that males restrict their range at the onset of the mating season and perform vocal and dive displays. While these data illustrated broad changes in male behaviour and distribution, they were not precise enough to reveal the extent to which individual males repeatedly return to the same locations to display. In this study we used an acoustic array to localise male vocalisations. This technique provided small-scale information on male behaviour over 3 consecutive years. This study provides the first details concerning display-area size in an aquatically mating phocid. Male vocalisations were located in two discrete areas each covering between 40 and 135 m2. Vocalisations were repeatedly located in these two areas over the 3-year period. Comparisons of four vocal parameters suggested that only one individual occupied each area throughout a mating season. Furthermore, comparative analysis suggested that males might return to the same two display areas in successive years. Although the number of males using the site was small, this study showed that acoustic localisation can be a valuable tool for detailed study of the underwater behaviour of aquatically mating pinnipeds.

scholarly journals Catch history and status of the harbour seal (Phoca vitulina) in Greenland

2010 ◽  
Vol 8 ◽  
pp. 161 ◽  
Author(s):  
Aqqalu Rosving-Asvid
Keyword(s):  
West Coast ◽  
Large River ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
South Eastern ◽  
The Past ◽  
Frequency Of Contact ◽  
Harbour Seals ◽  
Ice Drift ◽  
Catch Statistics

The number of harbour seals (Phoca vitulina) in West Greenland declined rapidly after the 1950s and the seals have now abandoned their traditional haulout locations along the Greenland west coast. However, in recent years, a previously undetected group of about 60-100 harbour seals has been observed approximately 80 km upstream in a large river, and some traditional hauloutlocations are still in use near the south-eastern tip of Greenland. A small number of harbour seals is caught annually far from any of these locations, indicating that other groups might live unnoticed. Catch statistics provide the best evidence of the presence and locations of these remnant harbour seals. Therefore efforts were made to validate the recent catch statistics and to describe the catch history for the past 60 years. The catch statistics were also used to estimate plausibleranges of past and present numbers of harbour seals based on the assumption that hunting has caused the observed decline. The total number of harbour seals in Greenland according to these estimates was about 3,000 in 1950 and fewer than 1,000 in 2007. The number of harbour seals caught in the southernmost part of Greenland has, unlike in the rest of Greenland, increased significantly in some of the recent years. This change seems to be related to changes in the amount of drift ice. Drift ice reduces the frequency of contact between hunters and harbour seals in South Greenland and above normal quantities of drift ice from the mid 1960s to the mid 1980s probably allowed these seals to increase in numbers. Record low inflow of drift ice in some of the recent years, however, has resulted in record high catches, which likely have reduced the seals again. The remaining harbour seals in Greenland are few and without protection these sealsare potentially in danger of extinction.

scholarly journals Predicting recurrent PDV epizootics in European harbour seals (Phoca vitulina)

2010 ◽  
Vol 8 ◽  
pp. 275 ◽  
Author(s):  
Tero Härkönen ◽  
Karin C Harding
Keyword(s):  
North Sea ◽  
Herd Immunity ◽  
Phoca Vitulina ◽  
High Rate ◽  
The North ◽  
Rate Of Spread ◽  
Phocine Distemper Virus ◽  
Harbour Seals ◽  
The North Sea ◽  
Sea Area

Phocine Distemper Virus (PDV) caused mass mortality in European harbour seals (Phoca vitulina) in 1988 and in 2002. Both epizootics likely originated from refugia in Arctic seals, where data indicate PDV hops among populations and species. The metapopulation structure of host populations is suggested to be the reason why PDV is preserved among Arctic seals, since the high rate of spread of PDV would require much larger panmictic populations to maintain an infection. The pattern of sudden outbreaks of PDVis also seen in grey seals (Halichoerus grypus), the only to date identified species that could act as a vector between Arctic and North Sea seal populations. Harbour seal populations along mainland Europe were below critical herd immunity levels by 3-5 years after the events, and thus vulnerable for new outbreaks, but historical data and the 14 years between the 2 epizootics suggest that harbour seals in the North Sea area are only rarely exposed to the infective agent. The risk for new outbreaks of the seal plague in North Sea harbour seals is likely linked to the dynamics of the disease in Arctic seal species as well asvector species.

scholarly journals Interactions between harbour seals (Phoca vitulina) and coastal fisheries along the Swedish west coast: an overview

2010 ◽  
Vol 8 ◽  
pp. 329 ◽  
Author(s):  
Karl Lundström ◽  
Sven-Gunnar Lunneryd ◽  
Sara Königson ◽  
Malin Hemmingsson
Keyword(s):  
West Coast ◽  
Current Data ◽  
Mitigation Measures ◽  
Swedish West Coast ◽  
Coastal Fisheries ◽  
Prey Preferences ◽  
New Information ◽  
Harbour Seals ◽  
By Catch ◽  
Fyke Nets

The conflicts between seals and fisheries along the Swedish west coast have intensified during the last decades, concurrently with the increase in the harbour seal population size. This study presents published information about interactions between harbour seals and fisheries in the Kattegat-Skagerrak, in addition to new information on the seal by-catch rate and an overview of fisheries suffering from seal damage. Several fisheries have reported interactions with seals, principally fisheries with fyke nets, gill nets and static gear. Development of mitigation measures has been focused on the eel fishery with fyke nets, in which the use of stronger net material has significantly decreased the damage frequency from seals and has yet maintained the catches at satisfactory levels. Under-water filming at fyke nets together with studies of the prey preferences of seals has shown individual specializations in certain foraging techniques. For example, eel may not be a common prey for harbour seals in general, but, it was chosen in preference to other species by seals attacking fyke nets. There is a lack of current data concerning the diet of harbour seals. Previous studies, based on material from the 1970s and 1980s, have shown that locally and seasonally abundant prey is preferred. Due to the non-existent information about the foodchoice, current assessments of the ecological role of harbour seals in Sweden cannot be evaluated.

Differentiation and Interrelations of Two Representatives of Laudakia stellio Complex (Reptilia: Agamidae) in Israel

2011 ◽  
Vol 4 (2) ◽  
pp. 102-114 ◽  
Author(s):  
Evgenyi N. Panov ◽  
Larissa Yu. Zykova
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Habitat Preference ◽  
Additional Data ◽  
Near East ◽  
Field Studies ◽  
Subspecies Level ◽  
Limited Gene Flow ◽  
Study Sites ◽  
And Behavior

Field studies were conducted in Central Negev within the breeding range of Laudakia stellio brachydactyla and in NE Israel (Qyriat Shemona) in the range of an unnamed form (tentatively “Near-East Rock Agama”), during March – May 1996. Additional data have been collected in Jerusalem at a distance of ca. 110 km from the first and about 170 km from the second study sites. A total of 63 individuals were caught and examined. The animals were marked and their subsequent movements were followed. Social and signal behavior of both forms were described and compared. Lizards from Negev and Qyriat Shemona differ from each other sharply in external morphology, habitat preference, population structure, and behavior. The differences obviously exceed the subspecies level. At the same time, the lizards from Jerusalem tend to be intermediate morphologically between those from both above-named localities, which permits admitting the existence of a limited gene flow between lizard populations of Negev and northern Israel. The lizards from NE Israel apparently do not belong to the nominate subspecies of L. stellio and should be regarded as one more subspecies within the species.

Population fragmentation causes inadequate gene flow and increases extinction risk

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Gene Flow ◽  
Extinction Risk ◽  
Random Mating ◽  
Large Population ◽  
Isolated Population ◽  
Population Fragmentation ◽  
Single Population ◽  
Total Size ◽  
Limited Gene Flow

Most species now have fragmented distributions, often with adverse genetic consequences. The genetic impacts of population fragmentation depend critically upon gene flow among fragments and their effective sizes. Fragmentation with cessation of gene flow is highly harmful in the long term, leading to greater inbreeding, increased loss of genetic diversity, decreased likelihood of evolutionary adaptation and elevated extinction risk, when compared to a single population of the same total size. The consequences of fragmentation with limited gene flow typically lie between those for a large population with random mating and isolated population fragments with no gene flow.

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