Diving patterns of harbour seals (Phoca vitulina) in the Wadden Sea, the Netherlands and Germany, as indicated by VHF telemetry

1997 ◽  
Vol 75 (12) ◽  
pp. 2063-2068 ◽  
Author(s):  
Edith H. Ries ◽  
Petra Paffen ◽  
Ilona M. Traut ◽  
Paul W. Goedhart
Keyword(s):  
The Netherlands ◽  
Body Length ◽  
Air Temperature ◽  
Adult Male ◽  
Wadden Sea ◽  
Ambient Air ◽  
Phoca Vitulina ◽  
Late Autumn ◽  
Dive Behaviour ◽  
Harbour Seals

The diving behaviour of 25 harbour seals, Phoca vitulina (14 females and 11 males), of various body lengths was monitored by means of VHF telemetry at different locations in the Wadden Sea during late autumn in 1991 and 1992. Median dive durations for individual seals ranged from 46 s to 2.9 min. The maximum dive recorded was 31 min, performed by an adult male, which represents the longest dive reported for harbour seals. Dive endurance increased significantly in relation to body length. Female harbour seals tended to perform fewer short dives and had a more narrow distribution of dive times. We detected no diurnal differences in dive behaviour and only the ambient air temperature was found to influence the duration of surface periods, in that surface intervals tended to be shorter when temperatures were below 9 °C. The overall mean percentage of dive time was 85%, with individuals varying from 76 to 93%, and was in general higher in females.

scholarly journals Options for modulating intra-specific competition in colonial pinnipeds: the case of harbour seals (Phoca vitulina) in the Wadden Sea

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e957 ◽  
Author(s):  
Rory P. Wilson ◽  
Nikolai Liebsch ◽  
Agustina Gómez-Laich ◽  
William P. Kay ◽  
Andrew Bone ◽  
...  
Keyword(s):  
Wadden Sea ◽  
Phoca Vitulina ◽  
Harbour Seals

Population development of harbour seals Phoca vitulina in the Wadden Sea after the 1988 virus epizootic

1997 ◽  
Vol 38 (1-2) ◽  
pp. 161-168 ◽  
Author(s):  
Peter J.H. Reijnders ◽  
Edith H. Ries ◽  
Svend Tougaard ◽  
Niels Nørgaard ◽  
Günter Heidemann ◽  
...  
Keyword(s):  
Wadden Sea ◽  
Phoca Vitulina ◽  
Population Development ◽  
Harbour Seals

The importance of the North Sea for winter dispersal of harbour seals Phoca vitulina from the Wadden Sea

1997 ◽  
Vol 81 (1-2) ◽  
pp. 97-102 ◽  
Author(s):  
Mardik F. Leopold ◽  
Bert van der Werf ◽  
Edith H. Ries ◽  
Peter J.H. Reijnders
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
Phoca Vitulina ◽  
The North ◽  
Harbour Seals ◽  
The North Sea

scholarly journals Earlier pupping in harbour seals, Phoca vitulina

2010 ◽  
Vol 6 (6) ◽  
pp. 854-857 ◽  
Author(s):  
Peter J. H. Reijnders ◽  
Sophie M. J. M. Brasseur ◽  
Erik H. W. G. Meesters
Keyword(s):  
Life History Traits ◽  
Annual Variation ◽  
Wadden Sea ◽  
Phoca Vitulina ◽  
Birth Date ◽  
Embryonic Diapause ◽  
Potential Mechanism ◽  
Annual Reproductive Cycle ◽  
Harbour Seals ◽  
Large Predator

The annual reproductive cycle of most seal species is characterized by a tight synchrony of births. Typically, timing of birth shows little inter-annual variation. Here, however we show that harbour seals Phoca vitulina from the Wadden Sea (southeast North Sea) have shortened their yearly cycle, moving parturition to earlier dates since the early 1970s. Between 1974 and 2009, the birth date of harbour seals shifted on average by −0.71 d yr −1 , three and a half weeks (25 days) earlier, in the Dutch part of the Wadden Sea. Pup counts available for other parts of the Wadden Sea were analysed, showing a similar shift. To elucidate potential mechanism(s) for this shift in pupping phenology, possible changes in population demography, changes in maternal life-history traits and variations in environmental conditions were examined. It was deduced that the most likely mechanism was a shortening of embryonic diapause. We hypothesize that this could have been facilitated by an improved forage base, e.g. increase of small fishes, attributable to overfishing of large predator fishes and size-selective fisheries.

scholarly journals Harbour seals (Phoca vitulina) and rehabilitation

2010 ◽  
Vol 8 ◽  
pp. 355 ◽  
Author(s):  
Nynke Osinga ◽  
Pieter ‘t Hart
Keyword(s):  
Social Support ◽  
Anthropogenic Impact ◽  
Wadden Sea ◽  
Quality Standards ◽  
Phoca Vitulina ◽  
The Past ◽  
Harbour Seals ◽  
Seal Population ◽  
One Year ◽  
Ecosystem Changes

Throughout the past few decades, rehabilitation of seals has become an activity that is anchored in the present day society of many countries. Seals are primarily rehabilitated to help individual animals in distress. At the same time, the release of seals which would have otherwise died can be considered as a contribution to the population. Most rehabilitated seals are animals under one year of age. They are mainly orphans, weaned seals with complications and seals with a parasiticbronchopneumonia. For the optimal handling of seals and their diseases, centralised operations with quality standards are essential. Rehabilitation provides an instrument to monitor the health of the seal population and its ecosystem. Changes in stranding trends or the appearance of new diseases can be monitored. Moreover, rehabilitation is important to show the general public thestate of the marine environment. In the Netherlands there is significant social support for the rehabilitation of seals. Experience obtained with seal care is of importance in countries where urgent help of threatened seal species is required. Here individual seals are also ambassadors to raise support for the protection of this species in general. Given that the anthropogenic impact on the seals and their environment is extensive in the Wadden Sea, rehabilitation centres can compensate the consequences of this impact on individual seals as well as the population as a whole.

Plastic ingestion by harbour seals (Phoca vitulina) in The Netherlands

2013 ◽  
Vol 67 (1-2) ◽  
pp. 200-202 ◽  
Author(s):  
Elisa L. Bravo Rebolledo ◽  
Jan A. Van Franeker ◽  
Okka E. Jansen ◽  
Sophie M.J.M. Brasseur
Keyword(s):  
The Netherlands ◽  
Phoca Vitulina ◽  
Harbour Seals

scholarly journals Tooth Microwear Texture in the Eastern Atlantic Harbour Seals (Phoca vitulina vitulina) of the German Wadden Sea and Its Implications for Long Term Dietary and Ecosystem Changes

2021 ◽  
Vol 9 ◽  
Author(s):  
Elehna Bethune ◽  
Ellen Schulz-Kornas ◽  
Kristina Lehnert ◽  
Ursula Siebert ◽  
Thomas M. Kaiser
Keyword(s):  
Health Status ◽  
Marine Mammal ◽  
Marine Mammals ◽  
Wadden Sea ◽  
Anthropogenic Impacts ◽  
Phoca Vitulina ◽  
Dental Microwear ◽  
Future Health ◽  
Terrestrial Mammals ◽  
Harbour Seals

Marine mammals are increasingly threatened in their habitat by various anthropogenic impacts. This is particularly evident in prey abundance. Understanding the dietary strategies of marine mammal populations can help predict implications for their future health status and is essential for their conservation. In this study we provide a striking example of a new dietary proxy in pinnipeds to document marine mammal diets using a dental record. In this novel approach, we used a combination of 49 parameters to establish a dental microwear texture (DMTA) as a dietary proxy of feeding behaviour in harbour seals. This method is an established approach to assess diets in terrestrial mammals, but has not yet been applied to pinnipeds. Our aim was to establish a protocol, opening DMTA to pinnipeds by investigating inter- and intra-individual variations. We analysed the 244 upper teeth of 78 Atlantic harbour seals (Phoca vitulina vitulina). The specimens were collected in 1988 along the North Sea coast (Wadden Sea, Germany) and are curated by the Zoological Institute of Kiel University, Germany. An increasing surface texture roughness from frontal to distal teeth was found and related to different prey processing biomechanics. Ten and five year old individuals were similar in their texture roughness, whereas males and females were similar to each other with the exception of their frontal dentition. Fall and summer specimens also featured no difference in texture roughness. We established the second to fourth postcanine teeth as reference tooth positions, as those were unaffected by age, sex, season, or intra-individual variation. In summary, applying indirect dietary proxies, such as DMTA, will allow reconstructing dietary traits of pinnipeds using existing skeletal collection material. Combining DMTA with time series analyses is a very promising approach to track health status in pinniped populations over the last decades. This approach opens new research avenues and could help detect dietary shifts in marine environments in the past and the future.

scholarly journals Options for modulating intra-specific competition in colonial pinnipeds: the case of harbour seals (Phoca vitulina) in the Wadden Sea

2015 ◽  
Author(s):  
Rory P Wilson ◽  
Nikolai Liebsch ◽  
Agustina Gomez-Laich ◽  
William P. Kay ◽  
Andrew Bone ◽  
...  
Keyword(s):  
Time Use ◽  
Wadden Sea ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Central Place ◽  
Phoca Vitulina ◽  
Harbour Seals ◽  
Slow Moving ◽  
Sea Area ◽  
Three Dimensional Space

Colonial pinnipeds may be subject to substantial consumptive competition because they are large, slow-moving central place foragers. We examined possible mechanisms for reducing this competition by examining the diving behaviour of harbour seals (Phoca vitulina) after equipping 34 seals (11 females, 23 males) foraging from three locations; Rømø, Denmark and Lorenzenplate and Helgoland, Germany, in the Wadden Sea area with time-depth recorders. Analysis of 319,021 dives revealed little between-colony variation but appreciable inter-sex differences, with males diving deeper than females, but for shorter periods. Males also had higher vertical descent rates. This result suggests that males may have higher overall swim speeds, which would increase higher oxygen consumption, and may explain the shorter dive durations compared to females. Intersex variation in swim speed alone is predicted to lead to fundamental differences in the time use of three-dimensional space, which may help reduce consumptive competition in harbour seals and other colonial pinnipeds.

Sign in / Sign up

Export Citation Format

Share Document