Change search
ReferencesLink to record
Permanent link

Direct link
Istäckets påverkan på öringens (Salmo trutta) rumsliga utbredning i ett vattendrag
Karlstad University, Faculty of Health, Science and Technology (starting 2013).
2014 (Swedish)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesisAlternative title
The effect of ice-cover on the spatial distribution of brown trout (Salmo trutta) in a small stream (English)
Abstract [en]

Little is known about the behavior of juvenile brown trout (Salmo trutta) during winter in boreal streams. Harsh winter conditions presumably affect overwinter survival negatively in small streams, where ice may have a large effect on survival of young salmonids. The aim of this study was to examine the effect of over-head ice cover on the spatial positioning of small brown trout in a boreal stream. I hypothesized that during the day brown trout will use the middle of the stream to a greater extent in the presence of over-head ice cover than in its absence. In the absence of ice cover, trout were predicted to hold station near the shore. At night, I hypothesized that there will be little effect of ice cover on the spatial positioning of the trout, with trout expected to occupy the entire stream width. Analysis of the results for the entire study period revealed a strong positive correlation between the tendency to be positioned towards the middle of the stream during daytime and the presence of ice cover. An analysis based on the period when water temperature was around 0o C (< 0,3o C) showed that trout used the entire width of the stream in the presence of surface ice but were restricted to the margins in the absence of ice. My hypothesis regarding the spatial distribution of trout at night was not supported by the data, as there was no difference in their spatial distribution during the day and at night.

Abstract [sv]

Det råder stor okunskap om hur vinterförhållanden påverkar överlevnaden av juvenila öringar (Salmo trutta) i boreala områden. Isformationer och dess bildningsprocesser kan ha avgörande effekt på mortaliteten hos unga öringar som övervintrar i mindre vattendrag. Denna studie handlar om istäckets påverkan på öringens positionering längs vattendragets bredd. Hypoteserna är 1) att närvaron av istäcket ger öringen större möjlighet att kunna utnyttja mer metaboliskt gynnsamma ståndplatser i vattendraget än utan is och 2) att istäcket har effekt på daglig respektive nattlig positionering ifrån strandkanten. Resultaten i studien visar ett starkt positivt förhållande mellan ökad andel istäckningsgrad och positionering längre ut från strandkanten mot mitten av vattendraget. Vidare visar mina resultat, som baseras på perioden när vattentemperaturen var runt 0C (< 0,3C), att öringen använde sig av hela vattendragets bredd i närvaro av istäcke, men var nära strandkanten vid frånvaro av istäcket. Min hypotes angående öringens rumsliga fördelning under natten stöds inte av resultatet, då det inte fanns någon skillnad i deras rumsliga fördelning under dagen respektive på natten.

Place, publisher, year, edition, pages
2014. , 8 p.
Keyword [en]
Salmo trutta, spatial distribution, effect of ice-cover, ice-cover
Keyword [sv]
Öring, rumsliga utbredning, Salmo trutta, istäcke
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:kau:diva-34449OAI: oai:DiVA.org:kau-34449DiVA: diva2:757045
Subject / course
Biology
Educational program
Biology programme, 180 hp
Supervisors
Examiners
Available from: 2014-10-22 Created: 2014-10-20 Last updated: 2014-10-22Bibliographically approved

Open Access in DiVA

Oscar Askling(1389 kB)66 downloads
File information
File name FULLTEXT01.pdfFile size 1389 kBChecksum SHA-512
a6e7b8b4fd1646f8cce56d90aa7f32649c7423de3b7c5ee1c78ce9ad8f0e7c6f7e9230188ca69720984e436ddd660b15ec6c45bc7c07978fed21cba46ba2fdce
Type fulltextMimetype application/pdf

By organisation
Faculty of Health, Science and Technology (starting 2013)
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 66 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 170 hits
ReferencesLink to record
Permanent link

Direct link