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  • Nyberg, Elisabeth
    et al.
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Aune, Marie
    Livsmedelsverket.
    Awad, Raed
    Stockholms Universitet.
    Benskin, Jon
    Stockholms Universitet.
    Bergh, Arpi
    Livsmedelsverket.
    Bignert, Anders
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Dahlgren, Henrik
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Danielsson, Sara
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    de Wit, Cynthia
    Stockholms Universitet.
    Egebäck, Anna-Lena
    Stockholms Universitet.
    Ek, Caroline
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Eriksson, Ulla
    Stockholms Universitet.
    Kruså, Martin
    Stockholms Universitet.
    Näslund, Mathilda
    Livsmedelsverket.
    Sallsten, Gerd
    Göteborgs Universitet.
    Monitoring of POPs in human milk from Stockholm and Gothenburg, 1972-20152017Report (Other academic)
  • Bäcklin, Britt-Marie
    et al.
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Strömberg, Annika
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Moraeus, Charlotta
    Härkönen, Tero
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Karlsson, Olle
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Undersökning av sälar insamlade 20152017Report (Other academic)
    Abstract [en]

    Since the 1970s, grey seals (Halichoerus grypus), harbour seals (Phoca vitulina) and ringed seals (Phoca hispida) have been collected and necropsied at the Swedish Museum of Natural History. Mostly have grey seals been examined. The effect of hunting during 19th century and reproductive failure during the latter half of the century decreased Baltic seal populations. In the 1970s and 1980s, pathological changes found mostly in grey seals was called the Baltic Seal Disease Complex and was thought to be related to high levels of PCB and DDT. Since then several pathological changes have decreased in prevalence as well as levels of PCB and DDT. Since then in grey seals, the prevalence of intestinal ulcers has increased and then decreased, blubber thickness has decreased and the prevalence of a zoonotic biliary trematode infection increased.

    In 2015, whole bodies and samples from 137 grey seals, 44 harbour seals and 27 ringed seals were examined at the museum. The public reported 196 seals found dead along the Swedish coast. At present, the Baltic grey seal population increases with 8% each year and 85% of the examined females 6-24 years old were pregnant during the pregnant period (August-February) in 2015. The harbour seal populations presently increase with 7-9 % per year, although the numbers of examined harbour seals are much lower than the number of grey seals, the proportion of examined pregnant harbour seals in corresponding age group was only 57%. The ringed seal population in the Gulf of Bothnia presently increase with 4,5% per year. One mature female examined from the period of pregnancy was pregnant. Of the examined 27 ringed seals, 20 of them were younger than 4 years. Two two-year old females showed malformations as diaphragmatic hiatus in one of them and the other female lacked one of the uterine horns.

     

    In conclusion, the health situation for examined Baltic grey seals is better and the increase in the population during the last 15 years is stable. The number of examined harbour seals and ringed seals is small for presenting trends but harbour seals showed a tendency to low pregnancy rate that needs further studies. The populations of harbour seals on the Swedish west coast were affected by epidemics in 1988, 2002 and 2014 and the development rate of these populations have decreased since 2002. The development of the harbour seal population on the Swedish east coast has a steady increase since the 1970s. The population of ringed seals has a low increase in the Gulf of Bothnia