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Wärnsberg, Johanna, 2016. Estimation of maximum densities of young of the year brown trout, Salmo trutta, with the use of environmental factors. Second cycle, A2E. Umeå: SLU, Dept. of Wildlife, Fish and Environmental Studies



Brown trout, Salmo trutta, is an important species for the sportfishing tourism in Sweden
and goals are set high for the possible gains to come from fishing tourism. Therefore
accurate and efficient methods to estimate a streams potential production of brown trout are
needed in order to apply relevant management regimes that take fish ecology into account
and prevents overfishing. One measure of brown trout production is the density of young of
the year fish. The usual method for estimation of young of the year brown trout density are
electrofishing with three removals. In this study a method using environmental factors to
estimate maximum production of young of the year brown trout, as a measure of carrying
capacity, was used. Based on previous studies environmental factors important for brown
trout habitat requirement were selected. Data of stream slope, water flow, annual air
temperature, longest period above 0 °C, altitude, stream width and water depth were linked
to data on young of the year densities in a cluster analysis. The percentage relative
precision values for the estimated mean maximum densities showed a lower level of
uncertainty for density estimates based on environmental factors and cluster analysis than
for estimates based on electrofishing with three removals. An additional benefit of the use
of environmental data for estimations of maximum young of the year brown trout density is
that estimates can easier be scaled up to cover a whole stream without the use of long time
series of data. As opposed to estimation of brown trout production capacity for a whole
stream using electrofishing data which for reliable estimates require over time data (e.g. 10-
15 years).

Main title:Estimation of maximum densities of young of the year brown trout, Salmo trutta, with the use of environmental factors
Authors:Wärnsberg, Johanna
Supervisor:Leonardsson, Kjell
Examiner:Alanärä, Anders
Series:Examensarbete i ämnet biologi / Sveriges lantbruksuniversitet, Institutionen för vilt, fisk och miljö
Volume/Sequential designation:2016:14
Year of Publication:2016
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SM003 Management of Fish and Wildlife Populations - Master's Programme 120 HEC
Supervising department:(S) > Dept. of Wildlife, Fish and Environmental Studies
Keywords:Salmo trutta, young of the year, density, environmental factors
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Fisheries and aquaculture - General aspects
Deposited On:10 Nov 2016 14:40
Metadata Last Modified:10 Nov 2016 14:40

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