Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream

Rainbow trout, originally from Pacific coast catchments (North America), have been distributed extensively on a global scale for consumptive and recreational fishing. Consequently, the species now occurs widely in freshwater ecosystems around the world. The reasons for the success or failure of self...

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Main Authors: Kurt Pinter, Marlene Kollmann, Erwin Lautsch, Günther Unfer
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Global Ecology and Conservation
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Online Access:http://www.sciencedirect.com/science/article/pii/S2351989425002513
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author Kurt Pinter
Marlene Kollmann
Erwin Lautsch
Günther Unfer
author_facet Kurt Pinter
Marlene Kollmann
Erwin Lautsch
Günther Unfer
author_sort Kurt Pinter
collection DOAJ
description Rainbow trout, originally from Pacific coast catchments (North America), have been distributed extensively on a global scale for consumptive and recreational fishing. Consequently, the species now occurs widely in freshwater ecosystems around the world. The reasons for the success or failure of self-sustaining populations that settle in watersheds outside of their natural range have been the subject of debate for decades. This study investigates the establishment and persistence of a rainbow trout population in a perialpine central European stream. Our analysis combines hydrological data with a 27 year-long time series (1997–2023) of annual data on the abundance of sympatric rainbow trout and brown trout populations. Despite the cessation of fish stocking since 1997, rainbow trout persist as a self-sustaining and robust population. A number of stream characteristics are hypothesized as critical to their persistence in this stream. First, high pre-spawn flows generally lead to enhanced recruitment of rainbow trout. This pattern likely results from the flushing of substrate sediments, thus improving the quality of spawning habitat. Conversely, high discharge during the fry-emergence period negatively impacts juvenile densities. Rainbow trout exhibit higher relative production of juvenile fish compared to native brown trout but experience a sharp decline in densities from young of the year to age 1 + class. This decline can be attributed to either mortality or outmigration of rainbow trout from the stream reach due to the predominance of native brown trout – the numerically dominant species (66 %) in the study area. Although brown trout remain dominant within the study’s stream reach, our study highlights the potential of rainbow trout’s invasiveness demonstrated by a consistently positive population trend and emphasizes the need for increased vigilance towards this species, relative to the native brown trout.
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spelling doaj-art-2ce5eae07c384f1d93487b65e78622e22025-08-20T03:24:06ZengElsevierGlobal Ecology and Conservation2351-98942025-09-0161e0365010.1016/j.gecco.2025.e03650Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone streamKurt Pinter0Marlene Kollmann1Erwin Lautsch2Günther Unfer3Corresponding author.; BOKU University, Institute of Hydrobiology and Aquatic Ecosystem Management, Gregor-Mendelstrasse 33, Vienna 1180, AustriaBOKU University, Institute of Hydrobiology and Aquatic Ecosystem Management, Gregor-Mendelstrasse 33, Vienna 1180, AustriaBOKU University, Institute of Hydrobiology and Aquatic Ecosystem Management, Gregor-Mendelstrasse 33, Vienna 1180, AustriaBOKU University, Institute of Hydrobiology and Aquatic Ecosystem Management, Gregor-Mendelstrasse 33, Vienna 1180, AustriaRainbow trout, originally from Pacific coast catchments (North America), have been distributed extensively on a global scale for consumptive and recreational fishing. Consequently, the species now occurs widely in freshwater ecosystems around the world. The reasons for the success or failure of self-sustaining populations that settle in watersheds outside of their natural range have been the subject of debate for decades. This study investigates the establishment and persistence of a rainbow trout population in a perialpine central European stream. Our analysis combines hydrological data with a 27 year-long time series (1997–2023) of annual data on the abundance of sympatric rainbow trout and brown trout populations. Despite the cessation of fish stocking since 1997, rainbow trout persist as a self-sustaining and robust population. A number of stream characteristics are hypothesized as critical to their persistence in this stream. First, high pre-spawn flows generally lead to enhanced recruitment of rainbow trout. This pattern likely results from the flushing of substrate sediments, thus improving the quality of spawning habitat. Conversely, high discharge during the fry-emergence period negatively impacts juvenile densities. Rainbow trout exhibit higher relative production of juvenile fish compared to native brown trout but experience a sharp decline in densities from young of the year to age 1 + class. This decline can be attributed to either mortality or outmigration of rainbow trout from the stream reach due to the predominance of native brown trout – the numerically dominant species (66 %) in the study area. Although brown trout remain dominant within the study’s stream reach, our study highlights the potential of rainbow trout’s invasiveness demonstrated by a consistently positive population trend and emphasizes the need for increased vigilance towards this species, relative to the native brown trout.http://www.sciencedirect.com/science/article/pii/S2351989425002513Abiotic conditionsBrown trout (Salmo trutta) competitionCohort developmentInvasivenessManagementRainbow trout (Oncorhynchus mykiss)
spellingShingle Kurt Pinter
Marlene Kollmann
Erwin Lautsch
Günther Unfer
Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
Global Ecology and Conservation
Abiotic conditions
Brown trout (Salmo trutta) competition
Cohort development
Invasiveness
Management
Rainbow trout (Oncorhynchus mykiss)
title Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
title_full Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
title_fullStr Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
title_full_unstemmed Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
title_short Population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
title_sort population dynamics and the influence of hydrology on nonnative rainbow trout in a perialpine limestone stream
topic Abiotic conditions
Brown trout (Salmo trutta) competition
Cohort development
Invasiveness
Management
Rainbow trout (Oncorhynchus mykiss)
url http://www.sciencedirect.com/science/article/pii/S2351989425002513
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