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 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.

Unravelling the effects of water temperature and density dependence on the spatial variation of brown trout (Salmo trutta) body size

2012 ◽  
Vol 69 (5) ◽  
pp. 821-832 ◽  
Author(s):  
Irene Parra ◽  
Ana Almodóvar ◽  
Daniel Ayllón ◽  
Graciela G. Nicola ◽  
Benigno Elvira
Keyword(s):  
Body Size ◽  
Spatial Variation ◽  
Density Dependence ◽  
Water Temperature ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Maximum Growth ◽  
Suitable Habitat ◽  
Brown Trout Salmo Trutta ◽  
Potential Maximum

This study looks at the relative influence of water temperature and density dependence on the spatial variation in body size of 126 brown trout ( Salmo trutta ) cohorts from 12 Iberian rivers over a 12-year period. Mean cohort mass and length of age groups 0+ to 2+ varied significantly among sampling sites because of the concurrent effect of water temperature and density dependence. Density in suitable habitat had a limiting role that influenced potential maximum growth of cohorts, and water temperature differentiated these cohorts in two groups of sites with high and low potential maximum growth. Water temperature had a positive cumulative effect on body size of all age classes. However, body size of age-0 trout was nonlinearly influenced by short-term exposure to extreme water temperature. Thus, extremely high temperatures became a limiting factor and had deleterious effects on growth. There were intracohort and intercohort effects of density dependence throughout the life span, which were mainly due to the density in the available suitable habitat of trout of the same age or older. The present study supports the hypothesis that both density-dependent and density-independent processes are crucial for the understanding of population dynamics and that their relative importance varies across scales of space and time.

scholarly journals Genomic consequences of a recent three-way admixture in supplemented wild brown trout populations revealed by ancestry tracts

2018 ◽  
Author(s):  
Maeva Leitwein ◽  
Pierre-Alexandre Gagnaire ◽  
Erick Desmarais ◽  
Patrick Berrebi ◽  
Bruno Guinand
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Natural Populations ◽  
Length Distribution ◽  
Wild Populations ◽  
Mediterranean Populations ◽  
Population Genomic ◽  
Evolutionary Consequences ◽  
Local Ancestry Inference ◽  
Detailed Picture

AbstractUnderstanding the evolutionary consequences of human-mediated introductions of domestic strains into the wild and their subsequent admixture with natural populations is of major concern in conservation biology. In the brown trout Salmo trutta, decades of stocking practices have profoundly impacted the genetic makeup of wild populations. Small local Mediterranean populations in the Orb River watershed (Southern France) have been subject to successive introductions of domestic strains derived from the Atlantic and Mediterranean lineages. However, the genomic impacts of two distinct sources of stocking (locally-derived vs divergent) on the genetic integrity of wild populations remain poorly understood. Here, we evaluate the extent of admixture from both domestic strains within three wild populations of this watershed, using 75,684 mapped SNPs obtained from double-digest restriction-site-associated DNA sequencing (dd-RADseq). Using a local ancestry inference approach, we provide a detailed picture of admixture patterns across the brown trout genome at the haplotype level. By analysing the chromosomal ancestry profiles of admixed individuals, we reveal a wider diversity of hybrid and introgressed genotypes than estimated using classical methods for inferring ancestry and hybrid pedigree. In addition, the length distribution of introgressed tracts retained different timings of introgression between the two domestic strains. We finally reveal opposite consequences of admixture on the level of polymorphism of the recipient populations between domestic strains. Our study illustrates the potential of using the information contained in the genomic mosaic of ancestry tracts in combination with classical methods based on allele frequencies for analysing multiple-way admixture with population genomic data.

Longevity, Body Size, and Growth in Anadromous Brown Trout (Salmo trutta)

1991 ◽  
Vol 48 (10) ◽  
pp. 1838-1845 ◽  
Author(s):  
Bror Jonsson ◽  
Jan Henning L'Abée-Lund ◽  
Tor G. Heggberget ◽  
Arne J. Jensen ◽  
Bjørn O. Johnsen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Water Temperature ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Ambient Water ◽  
Ambient Water Temperature ◽  
Brown Trout Salmo Trutta ◽  
Interpopulation Variation ◽  
Temperature And Growth

Longevity in 25 populations of anadromous brown trout (Salmo trutta) showed a significant trend with increasing life span at latitudes of 58–70°N in Norway, with the largest change from 58 to 60°N. Moreover, longevity was negatively correlated with temperature and growth rate in freshwater and at sea. Body size was negatively correlated with water temperature and growth rate in freshwater, but not with latitude or water temperature and growth rate at sea. Thus, conditions influencing development and metabolic rates in fresh water seem more important than conditions in the sea in determining variation in longevity and body size of anadromous brown trout. Our results support the hypothesis that interpopulation variation in longevity and body size is influenced by rate of metabolism, chiefly influenced by ambient water temperature.

Small-scale dispersal and population structure in stream-living brown trout (Salmo trutta) inferred by mark–recapture, pedigree reconstruction, and population genetics

2012 ◽  
Vol 69 (9) ◽  
pp. 1513-1524 ◽  
Author(s):  
Leif Asbjørn Vøllestad ◽  
Dimitar Serbezov ◽  
Arthur Bass ◽  
Louis Bernatchez ◽  
Esben Moland Olsen ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Isolation By Distance ◽  
Juvenile Fish ◽  
Age Groups ◽  
Small Scale ◽  
Mark Recapture ◽  
Small Stream ◽  
Brown Trout Salmo Trutta ◽  
Mature Fish

Many animals move among habitats, and even small-scale dispersal of individuals between habitat patches may have strong implications for population dynamics and structure. Here, we use long-term mark–recapture data combined with extensive genotyping and parentage assignment to investigate the importance of small-scale location change of resident brown trout ( Salmo trutta ) in a small stream (1500 m). During the first summer, juvenile fish dispersed downstream (mean displacement 200 m), with smaller juveniles dispersing longer distances. Downstream movement was also predominant during the first winter, but older fish moved little. This limited dispersal resulted in a significant isolation-by-distance structure for ages 1 and 2, but not for older age groups or for the mature fish. Individual pairwise relatedness coefficients decreased with waterway distance for mature fish during the 2002 and 2003 spawning seasons, but only weakly. Overall, between-site genetic differentiation was stronger for the younger age classes, and the signal decayed with age, indicating that the genetic structure observed in the stream is mainly driven by spatial aggregation of close relatives.

scholarly journals Life History Tactics in Cohorts of a Partial Migratory Brown Trout (Salmo trutta L.) Population

ISRN Ecology ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Ivan C. Olsson ◽  
Larry A. Greenberg
Keyword(s):  
Body Size ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Female Fecundity ◽  
Trout Population ◽  
Delayed Reproduction ◽  
Brown Trout Salmo Trutta ◽  
Downstream Section ◽  
And Migration ◽  
Brown Trout Population

We monitored temporal changes in body size for three cohorts of a partial migratory, lake-migrating brown trout population. We tested if body mass differed between nonmigratory males, migrants, and other members of the cohort (females and immature males). We hypothesized that large-sized individuals would mature as nonmigratory males or migrate at younger ages than small-sized individuals. As previous studies have shown that female fecundity is influenced by body size and that more trout from the downstream section (D) of the stream migrated than from the upstream section (U), we hypothesized that there would be a greater proportion of mature males in D than U. We found that body size of males that reproduced was similar to migrants that migrated the subsequent spring and larger than other cohort members. Reproducing males had a larger body size than equal-aged males that delayed reproduction. Similarly, individuals that migrated had a larger body size than equal-aged individuals that migrated subsequently. The proportion of mature males was greater in D than in U. The fact that body size differentiation occurred late in ontogeny and that age of maturation and migration varied within cohorts suggests that the decision to mature or migrate might be conditionally dependent.

scholarly journals No additive genetic variance for tolerance to ethynylestradiol exposure in natural populations of brown trout ( Salmo trutta )

2019 ◽  
Vol 12 (5) ◽  
pp. 940-950 ◽  
Author(s):  
Lucas Marques da Cunha ◽  
Anshu Uppal ◽  
Emily Seddon ◽  
David Nusbaumer ◽  
Etienne L.M. Vermeirssen ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Brown Trout Salmo Trutta
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