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Klättringssubstratets effekt på ålyngels beteende vid uppströmspassage
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
2017 (Swedish)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesisAlternative title
The effect of climbing substrate on the behavior of juvenile eel at upstream passages (English)
Abstract [en]

Because populations have declined drastically, the European eel (Anguilla anguilla) is now regarded as critically endangered, and there is a need for increased recruitment and remedial measures to improve passage in regulated rivers. One way to improve passage is to identify the most suitable type of climbing substrate, so that more juvenile eels will be able to pass river barriers and reach rearing grounds,where they eventually mature and become silver eels. The purpose of this study was to test how different climbing substrates affect eel behavior. In the study, I analyzed video films showing juvenile eels and their choices of and climbing behavior on three different climbing substrates: EF-16, Fish Pass and enkamat. EF-16 was a black plastic substrate paved with short thick pegs in the size of 2 cm each. Fish Pass had a light base with long green plastic bristles of about 1-2 mm thickness each put together in clusters of 1 cm where as enkamat was a dark gray web looking structure similar to steel wool. The results show that most eels chose ramps with EF-16 and eels using this substrate climbed with the highest velocity. This substrate also had the highest number of successful passages. Optimizing passage efficiency may be an important factor to increase the number of juvenile eels reaching their rearing habitat in freshwater, and may thus be one step towards a recovering European eel population.

 

Abstract [sv]

Eftersom bestånd minskat drastiskt betraktas numer den europeiska ålen (Anguilla anguilla) som akut hotad, varför det behövs åtgärder för att öka beståndet och botande åtgärder som att förbättra passager i reglerade älvar. Ett sätt att förbättra passagerna är att identifiera den mest lämpliga typen av klättringssubstrat, så att fler ålyngel kan klara sig förbi barriärer och nå uppväxtområden, där de till slut utvecklas till blankål. Syftet med denna studie var att testa olika substrats effekter på beteenden hos ålyngel. I studien analyserade jag videomaterial som visade ålynglens val av ramp med olika substrat och klättringsbeteende i de olika substraten: EF-16, Fish Pass och enkamat. EF-16 var ett svart plast substrat, belagt med korta tjocka piggar i storleken 2 cm styck. Fish Pass med ljust underlag hade långa smala gröna plastborst (ca 1-2 mm i diameter per styck) sammansatta i klungor av ca 1-2 cm tjocklek, medan enkamat var en mörk grå vävliknande struktur liknande stålull. Resultaten visade att EF-16 var det mest frekventa valet för glasålarna och det substrat där ålarna klättrade snabbast. EF-16 hade även flest antal lyckade passager. Att optimera passagelösningar för uppströmsvandrande ålyngel kan öka antalet ålar som når sina uppväxtområden, något som kan vara en avgörande faktor för att öka beståndet av den europeiska ålen.

Place, publisher, year, edition, pages
2017. , p. 10
Keywords [en]
European eel, endangered, upstream passage, climbing substrate, climbing behavior, juvenile eels
Keywords [sv]
europeisk ål, vandringsbeteende, klättringssubstrat, uppströmspassage, klättringsbeteende, ålyngel
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:kau:diva-55188OAI: oai:DiVA.org:kau-55188DiVA, id: diva2:1112106
Subject / course
Biology
Educational program
Biology programme, 180 hp
Presentation
(Swedish)
Supervisors
Examiners
Available from: 2017-06-26 Created: 2017-06-19 Last updated: 2017-06-26Bibliographically approved

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