scholarly journals Long-term mark-recapture and growth data for large-sized migratory brown trout (Salmo trutta) from Lake Mjøsa, Norway

2019 ◽  
Author(s):  
S. Jannicke Moe ◽  
Chloé R. Nater ◽  
Atle Rustadbakken ◽  
L. Asbjørn Vøllestad ◽  
Espen Lund ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Population Level ◽  
Freshwater Ecosystems ◽  
Data Series ◽  
Vital Rates ◽  
Growth Data ◽  
Mark Recapture ◽  
Adult Growth

AbstractBackgroundLong-term data from marked animals provide a wealth of opportunities for studies with high relevance to both basic ecological understanding and successful management in a changing world. The key strength of such data is that they allow to quantify individual variation in vital rates (e.g. survival, growth, reproduction) and then link it mechanistically to dynamics at the population level. However, maintaining the collection of individual-based data over long time periods comes with large logistic efforts and costs, and studies spanning over decades are therefore rare. This is the case particularly for migratory aquatic species, many of which are in decline despite their high ecological, cultural, and economical value.New informationThis paper describes two unique publicly available time series of individual-based data originating from a 51-year mark-recapture study of a land-locked population of large-sized migratory brown trout (Salmo trutta) in Norway: the Hunder trout. In the period 1966-2015, nearly 14,000 adult Hunder trout have been captured and individually marked during their spawning migration from Lake Mjøsa to the river Gubrandsdalslågen. Almost a third of those individuals were later recaptured alive during a later spawning run and/or captured by fishermen and reported dead or alive. This has resulted in the first data series: a mark-recapture-recovery dataset spanning half a century and more than 18,000 capture records. The second data series consists of additional data on juvenile and adult growth and life-history schedules from half of the marked individuals, obtained by means of scale sample analysis. The two datasets offer a rare long-term perspective on individuals and population dynamics and provide unique opportunities to gain insights into questions surrounding management, conservation, and restoration of migratory salmonid populations and freshwater ecosystems.

scholarly journals Long-term mark-recapture and growth data for large-sized migratory brown trout (Salmo trutta) from Lake Mjøsa, Norway

2020 ◽  
Vol 8 ◽  
Author(s):  
S. Jannicke Moe ◽  
Chloé Nater ◽  
Atle Rustadbakken ◽  
L. Asbjørn Vøllestad ◽  
Espen Lund ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Population Level ◽  
Freshwater Ecosystems ◽  
Data Series ◽  
Vital Rates ◽  
Growth Data ◽  
Mark Recapture ◽  
Adult Growth

Long-term data from marked animals provide a wealth of opportunities for studies with high relevance to both basic ecological understanding and successful management in a changing world. The key strength of such data is that they allow us to quantify individual variation in vital rates (e.g. survival, growth, reproduction) and then link it mechanistically to dynamics at the population level. However, maintaining the collection of individual-based data over long time periods comes with large logistic efforts and costs and studies spanning over decades are therefore rare. This is the case particularly for migratory aquatic species, many of which are in decline despite their high ecological, cultural and economical value. This paper describes two unique publicly available time series of individual-based data originating from a 51-year mark-recapture study of a land-locked population of large-sized migratory brown trout (Salmo trutta) in Norway: the Hunder trout. In the period 1966-2015, nearly 14,000 adult Hunder trout have been captured and individually marked during their spawning migration from Lake Mjøsa to the river Gubrandsdalslågen. Almost a third of those individuals were later recaptured alive during a later spawning run and/or captured by fishermen and reported dead or alive. This has resulted in the first data series: a mark-recapture-recovery dataset spanning half a century and more than 18,000 capture records. The second data series consists of additional data on juvenile and adult growth and life-history schedules from half of the marked individuals, obtained by means of scale-sample analysis. The two datasets offer a rare long-term perspective on individuals and population dynamics and provide unique opportunities to gain insights into questions surrounding management, conservation and restoration of migratory salmonid populations and freshwater ecosystems.

scholarly journals Size- and stage-dependence in cause-specific mortality of migratory brown trout

2019 ◽  
Author(s):  
Chloé Rebecca Nater ◽  
Yngvild Vindenes ◽  
Per Aass ◽  
Diana Cole ◽  
Øystein Langangen ◽  
...  
Keyword(s):  
Body Size ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Natural Populations ◽  
Reporting Rate ◽  
Vital Rates ◽  
Mark Recapture ◽  
Discrete State ◽  
Background Mortality ◽  
Specific Mortality

Evidence-based management of natural populations under strong human influence frequently requires not only estimates of survival but also knowledge about how much mortality is due to anthropogenic versus natural causes. This is the case particularly when individuals vary in their vulnerability to different causes of mortality due to traits, life-history stages, or locations. Here, we estimated harvest and background (other cause) mortality of a landlocked migratory salmonid over half a century. In doing so, we quantified among-individual variation in vulnerability to cause-specific mortality resulting from differences in body size and spawning location relative to a hydropower dam. We constructed a multistate mark-recapture model to estimate harvest and background mortality hazard rates as functions of a discrete state (spawning location) and an individual time-varying covariate (body size). We further accounted for among-year variation in mortality and migratory behavior and fit the model to a unique 50-year time-series of mark-recapture-recovery data on brown trout (Salmo trutta) in Norway. Harvest mortality was highest for intermediate-sized trout, and outweighed background mortality for most of the observed size range. Background mortality decreased with body size for trout spawning below the dam and increased for those spawning above. All vital rates varied substantially over time, but a trend was evident only in estimates of fishers' reporting rate, which decreased from over 50% to less than 10% throughout the study period. We highlight the importance of body size for cause-specific mortality and demonstrate how this can be estimated using a novel hazard rate parameterisation for mark-recapture models. Our approach allows estimating effects of individual traits and environment on cause-specific mortality without confounding, and provides an intuitive way to estimate temporal patterns within and correlation among different mortality sources.

scholarly journals Relative Mass of Brain- and Intestinal Tissue in Juvenile Brown Trout: No Long-Term Effects of Compensatory Growth; with Additional Notes on Emerging Sex-Differences

Fishes ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 38
Author(s):  
Joacim Näslund
Keyword(s):  
Sex Differences ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Compensatory Growth ◽  
Fork Length ◽  
Relative Mass ◽  
Long Term Effects ◽  
Treatment Groups ◽  
Trade Offs

This study investigated whether compensatory growth causes long-term effects in relative brain- or intestine size in a wild, predominantly anadromous, population of brown trout (Salmo trutta). The subject fish belonged to two treatment groups; one group had undergone starvation and subsequent growth compensation, while the other were unrestricted controls. The main hypothesis that compensatory growth would negatively affect brain and intestinal size, as a consequence of growth trade-offs during the compensatory phase, could not be supported as no significant differences were detected between the treatment groups. Further exploratory analyses suggested that males and females started to diverge in both brain and intestine size at around 130 mm fork length, with females developing relatively smaller brains and larger intestines. The size at which the differences appear is a typical size for smoltification (saltwater preadaptation), and females tend to smoltify to a higher proportion than males. Smoltification is known to cause a more elongated morphology and relatively smaller heads in salmonids, and the marine lifestyle is associated with rapid growth, which could require relatively larger intestines. Hence, these emerging sex differences could be a consequence of sex-biased smoltification rates. An investigation of wild smolts of both sexes indicated no differences in brain or intestine mass between male and female smolts.

Admixture analysis and stocking impact assessment in brown trout (Salmo trutta), estimated with incomplete baseline data

2001 ◽  
Vol 58 (9) ◽  
pp. 1853-1860 ◽  
Author(s):  
Michael M Hansen ◽  
Einar E Nielsen ◽  
Dorte Bekkevold ◽  
Karen-Lise D Mensberg
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Population Level ◽  
Genetic Distances ◽  
Scaling Analysis ◽  
Genetic Contribution ◽  
Multidimensional Scaling Analysis ◽  
Genetic Impact ◽  
Brown Trout Salmo Trutta ◽  
The Mean

Studies of genetic interactions between wild and domesticated fish are often hampered by unavailability of samples from wild populations prior to population admixture. We assessed the utility of a new Bayesian method, which can estimate individual admixture coefficients even with data missing from the populations contributing to admixture. We applied the method to analyse the genetic contribution of domesticated brown trout (Salmo trutta) in samples of anadromous trout from two stocked populations with no genetic data available before stocking. Further, we estimated population level admixture proportions by the mean of individual admixture coefficients. This method proved more informative than a multidimensional scaling analysis of individual-based genetic distances and assignment tests. The results showed almost complete absence of stocked, domesticated trout in samples of trout from the rivers. Consequently, stocking had little effect on improving fisheries. In one population, the genetic contribution by domesticated trout was small, whereas in the other population, some genetic impact was suggested. Admixture in this sample of anadromous trout despite absence of stocked domesticated trout could be because of introgression by domesticated trout adopting a resident life history.

scholarly journals A framework for estimating the determinants of spatial and temporal variation in vital rates and inferring the occurrence of unobserved extreme events

2015 ◽  
Author(s):  
Simone Vincenzi ◽  
Dušan Jesenšek ◽  
Alain J Crivelli
Keyword(s):  
Brown Trout ◽  
Extreme Events ◽  
Extreme Event ◽  
Flash Flood ◽  
Spatial And Temporal Variation ◽  
Source Population ◽  
Vital Rates ◽  
Population Densities ◽  
Poor Recruitment

AbstractWe develop an overarching framework that combines long-term tag-recapture data and powerful statistical and modeling techniques to investigate how population, environmental, and climate factors determine variation in vital rates and population dynamics in an animal species, using as a model system the population of brown trout living in Upper Volaja (Western Slovenia). This population has been monitored since 2004; Upper Volaja is also a sink, receiving individuals from a source population living above a waterfall. We estimate the numerical contribution of the source population on the sink population and test the effects of temperature, population density, and extreme events on variation in vital rates among more than 2,500 individually tagged brown trout. We found that fish dispersing downstream from the source population help maintain high population densities in the sink population despite poor recruitment. The best model of survival for individuals older than juveniles includes additive effects of year-of-birth and time. Fast growth of older cohorts and higher population densities in 2004-2005 suggest very low population densities in late1990s, which we hypothesize were caused by a flash flood that strongly reduced population size and created the habitat conditions for faster growth and transient higher population densities after the extreme event.

scholarly journals The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification

2021 ◽  
pp. 1-11
Author(s):  
Robert J. Needham ◽  
Martin Gaywood ◽  
Angus Tree ◽  
Nick Sotherton ◽  
Dylan Roberts ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Low Cost ◽  
Fork Length ◽  
Freshwater Ecosystems ◽  
Habitat Modification ◽  
Castor Fiber ◽  
Suitable Habitat ◽  
Eurasian Beaver ◽  
Brown Trout Salmo Trutta

Globally, freshwaters are the most degraded and threatened of all ecosystems. In northern temperate regions, beaver (Castor spp.) reintroductions are increasingly used as a low-cost and self-sustaining means to restore river corridors. River modifications by beavers can increase availability of suitable habitat for fish, including salmonids. This study investigated the response of a population of brown trout (Salmo trutta) to reintroduced Eurasian beaver (Castor fiber) habitat modifications in northern Scotland. The field site comprised two streams entering a common loch; one modified by beavers, the other unaltered. Electrofishing and PIT telemetry surveys indicated abundance of post-young-of-the-year (post-YOY) trout was higher in the modified stream. Considering juvenile year groups (YOY and post-YOY) combined, abundance and density varied with year and season. In the modified stream, fork length and mass were greater, there was a greater variety of age classes, and mean growth was positive during all seasons. Beavers had profound effects on the local brown trout population that promoted higher abundances of larger size classes. This study provides important insight into the possible future effect of beavers on freshwater ecosystems.

Sign in / Sign up

Export Citation Format

Share Document