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Gäddans val av lekvikar: Vilka faktorer bestämmer tätheterna av vuxna gäddor i Bottenhavets vikar?
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2023 (Swedish)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesisAlternative title
Choice of spawning habitats for the northern pike : What factors determine the density of adult pike in the bays of the Bothnian Sea? (English)
Abstract [en]

Northern pike (Esox lucius L) populations have been declining along the east coast of Sweden, including the Gävleborg coast. This negative trend is believed to be caused by factors related to pike recruitment including loss of suitable spawning habitats. The purpose of this study is to gain a deeper understanding for the recruitment process of pike by investigating their preferences when selecting spawning habitats. Data from a rod fishing inventory targeting adult pike was used to estimate pike densities in 20 assumed spawning bays along the coast of Gävleborg. By using the number of pike caught per hour as a measure of pike density I examined how the morphological characteristics of bays and fish communities influenced pike densities during the spawning period in the studied bays. The results suggest that the density of pike (# caught per hour) tend to increase in bays with deeper average depths, larger surface area, and higher densities of sticklebacks. These results contradict the hypothesis in the study and somewhat previous research. Possible explanations for these unexpected findings are discussed, and one theory suggest that the rod fishing method used may have influenced the results. Probably improvements can be made to make the density estimates from the fishing inventory more accurately, especially when comparing bays of varying sizes. Suggestions for enhancing density estimation include adjusting the fishing duration based on bay size or using a specific number of throws per casting rod and defined surface area and then move to next surface area.

Place, publisher, year, edition, pages
2023. , p. 12
Keywords [en]
Northern pike, Esox lucius, pike recruitment, spawning habitat, rod fishing inventory
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-210157OAI: oai:DiVA.org:umu-210157DiVA, id: diva2:1770684
External cooperation
Länsstyrelsen Gävleborg
Educational program
Bachelor of Science in Biology and Earthscience
Supervisors
Examiners
Available from: 2023-06-26 Created: 2023-06-19 Last updated: 2023-06-26Bibliographically approved

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CiteExportLink to record
Permanent link

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Citation style
  • apa
  • ieee
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  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf