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Knubbsälen i Kalmarsund
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
2014 (Swedish)Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Abstract [sv]

Knubbsälens beståndsutveckling i Kalmarsund styrs av flera faktorer som till exempel: överfiskning och bottendöd som reducerar mängden tillgänglig föda; fysiska störningar på reproduktionslokalerna vilket ökar kutdödligheten; miljögifter som påverkar hormonbalansen och immunförsvaret samt att populationen i Kalmarsund har en låg genetisk variation vilket gör dem extra sårbara (Härkönen, 2006).

Att ha tillgång till en metod med vilken man kan konstatera små förändringar i en sälpopulation kan göra att man tidigt får en indikation om att något händer i den marina miljön. Trots en stor hotbild så visar inventeringar att populationen ökar årligen sedan inventeringens start på 70-talet. I detta examensarbete ges en bakgrund till vilka faktorer som kan tänkas påverka knubbsälspopulationen i Kalmarsund och i arbetet presenteras dessutom en inventeringsmetodik som med hög styrka kan avslöja relativt små populationsförändringar. Resultaten visar att det skulle räcka med 5-6 års inventering för att med nittiofem procents säkerhet kunna avslöja en femprocentig ändring i populationstillväxt för knubbsälarna i Kalmarsund.

Abstract [en]

The population of harbor seal in the Baltic Sea is affected by many factors such as over-fishing and benthic dead zones which reduce available food; haul-out sites disturbances which can increase pup mortality; environmental toxins which disturb their hormonal balance and immune system, and the harbor seal population in Kalmar sound has a low genetic variation that makes them vulnerable.

To be able to observe early changes in the marine environment, it is important to have a survey methodology that is able to detect small changes in the seal population. Although many potential threats, the yearly population surveys shows an increase in the population since the start of the seventies. This thesis will give a background to the factors that might have an effect on the harbor seal population in Kalmar sound, and presents a population survey method with a high statistical power that is able to detect small population changes. The results show that it would take 5-6 years of surveying to detect a 5 percent increase in the population growth of the Kalmar sound harbor seals with a 95 percent statistical probability.

Place, publisher, year, edition, pages
2014. , p. 15
Keywords [sv]
Knubbsäl, säl, Kalmarsund, inventering, inventeringsmetodik, styrkestest
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:lnu:diva-37887OAI: oai:DiVA.org:lnu-37887DiVA, id: diva2:758988
Subject / course
Biology
Educational program
Biology Programme, 180 credits
Supervisors
Examiners
Available from: 2014-10-29 Created: 2014-10-28 Last updated: 2014-10-29Bibliographically approved

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CiteExportLink to record
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