Overwintering of sea trout (Salmo trutta) in freshwater: escaping salt and low temperature or an alternate life strategy?

2007 ◽  
Vol 64 (5) ◽  
pp. 793-802 ◽  
Author(s):  
Dennis S Thomsen ◽  
Anders Koed ◽  
Christian Nielsen ◽  
Steffen S Madsen
Keyword(s):  
Low Temperature ◽  
Water Temperature ◽  
Salmo Trutta ◽  
High Salinity ◽  
Life Strategy ◽  
Low Salinity ◽  
Sea Trout ◽  
Time Period ◽  
Coastal Sea ◽  
Brown Trout Salmo Trutta

Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2–3 years until migrating back to their native stream for reproduction. However, immature fish may leave the ocean during their first or second winter at sea and overwinter in freshwater. The question is why does this occur? We tested the hypothesis that hypo-osmoregulatory capacity is compromised by low temperature in two coastal sea trout populations, one representing high salinity and the other, low salinity. Immature sea-run trout were caught in lower parts of two rivers during winter and acclimated to laboratory conditions. Subgroups were challenged with high salinity or low water temperature or both, and their osmoregulatory performance was investigated. Low temperature compromised the hypo-osmoregulatory ability, as indicated by insufficient compensatory adjustments of ion-transport mechanisms. Tagging experiments revealed that descent of overwintering fish into the ocean occurred over a narrow time period coincident with increasing water temperature. We conclude that overwintering in freshwater is partly driven by compromised osmoregulatory physiology, but because not all fish in a population do so, the phenomenon may also reflect diverging life strategies.

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 Differing susceptibility of anadromous brown trout (Salmo trutta L.) populations to salmon louse (Lepeophtheirus salmonis (Krøyer, 1837)) infection

2003 ◽  
Vol 60 (5) ◽  
pp. 1139-1148 ◽  
Author(s):  
K.A Glover ◽  
Ø Skaala ◽  
F Nilsen ◽  
R Olsen ◽  
A.J Teale ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Trutta ◽  
Common Garden ◽  
Lepeophtheirus Salmonis ◽  
Infection Level ◽  
Salmon Louse ◽  
Sea Trout ◽  
Salmon Lice ◽  
Brown Trout Salmo Trutta ◽  
Farmed Atlantic Salmon

Abstract Three Norwegian sea trout (Salmo trutta L.) stocks and a farmed Atlantic salmon (Salmo salar L.) stock were challenged with salmon lice (Lepeophtheirus salmonis (Krøyer, 1837)), in a “common garden” experiment. Sea trout from the River Guddal exhibited a significantly lower level of infection, as measured by louse abundance and louse density, than other stocks. In addition, salmon lice developed significantly more slowly on the Guddal stock than on the other stocks. Salmon louse abundance and density were similar for the Rivers Fortun and Sima stocks of sea trout, and abundance of lice, though not density, was highest for farmed Atlantic salmon. Within stocks, there were no differences in infection levels of salmon louse between mature and immature fish, between sexes, or between anal-fin-clipped and non-clipped salmon. Differences in infection level among the sea trout stocks may, it is suggested, reflect genetic differences.

scholarly journals Climate Change Impact on Salmon (Salmo salar) and Sea Trout (Salmo trutta) in the Salaca River, Latvia

2020 ◽  
pp. 17-26
Author(s):  
Janis Birzaks
Keyword(s):  
Atlantic Salmon ◽  
Water Temperature ◽  
Salmo Salar ◽  
Salmo Trutta ◽  
Age Groups ◽  
Average Water Temperature ◽  
Sea Trout ◽  
The One ◽  
The Baltic

Hydrometeorological conditions are important determinants of the distribution, abundance and growth of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) parr and smolt in rivers. Long-term monitoring of the temperate zone Salaca River was conducted to investigate long-term changes in water temperature and streamflow and their effects on juvenile Atlantic salmon and sea trout. The average water temperature in the Salaca River was found to increase over time, particularly in autumn, winter and spring. River discharge increased in winter and summer, which was caused by increased precipitation. Goals of our study were: 1) to examine trends in water temperature and discharge in the river, 2) to explore relations between hydrometeorological trends, on the one hand, and abundance, size at age of salmon and sea trout parr and smolt, as well as changes in smolt migration patterns, on the other. This was the first occasion that a study of this type had been carried out in the Baltic Sea basin. In summer, growth of salmon parr in all age groups in the Salaca River was reduced. However, the size of smolt was found to increase. Migration of sea trout smolt in the Salaca River took place earlier, and the end of both salmon and sea trout migration was also observed earlier. The age structure of salmon smolt changed, with the one-year- old age group dominating. Judging from the total numbers of salmon and sea trout smolt in the River Salaca, production of smolt in the river during the monitoring period increased.

scholarly journals SEBARAN SUHU DAN SALINITAS DI TELUK MANADO

2013 ◽  
Vol 9 (2) ◽  
pp. 70 ◽  
Author(s):  
Patrice NI Kalangi ◽  
Anselun Mandagi ◽  
Kawilarang WA Masengi ◽  
Alfret Luasunaung ◽  
Fransisco PT Pangalila ◽  
...  
Keyword(s):  
Surface Layer ◽  
High Temperature ◽  
Low Temperature ◽  
River Discharge ◽  
High Salinity ◽  
Vertical Profiles ◽  
Salinity Distribution ◽  
Low Salinity ◽  
Water Column Stratification ◽  
North Sulawesi

Penelitian ini bertujuan untuk mendeskripsikan sebaran suhu dan salinitas di Teluk Manado, Sulawesi Utara. Pengukuran suhu dan salinitas secara vertikal dilakukan di delapan tempat di teluk. Profil vertikal suhu dan salinitas memperlihatkan keberadaan pelapisan kolom air. Secara horizontal, kontur suhu dan salinitas di permukaan memiliki dua “kolam” massa air, yakni kolam yang bersuhu tinggi tapi bersalinitas rendah di bagian timur teluk dan kolam yang bersuhu rendah tapi bersalinitas tinggi di bagian barat teluk. Pada lapisan dalam, kontur suhu dan salinitas cenderung sejajar dengan garis pantai bagian timur. Kata kunci: suhu, salinitas, air sungai, Teluk Manado.   The objective of this research is to describe temperature and salinity distribution in Manado Bay, North Sulawesi.  The vertical measurements of temperature and salinity were done at eight locations in the bay.  The vertical profiles of temperature and salinity shows the existence of water column stratification.  Horizontally, temperature and salinity contours of the surface layer have two pools, i.e. a pool of high temperature but low salinity in the eastern part of the bay and a pool of low temperature but high salinity in the western part of bay.  In a deeper layer, the contours of temperature and salinity tend to be parallel to eastern coastline. Keywords: temperature, salinity, river discharge, Manado Bay.

scholarly journals Understanding inter-reach variation in brown trout (Salmo trutta) mortality rates using a hierarchical Bayesian state-space model

2017 ◽  
Vol 74 (10) ◽  
pp. 1612-1627 ◽  
Author(s):  
Victor Bret ◽  
Hervé Capra ◽  
Véronique Gouraud ◽  
Nicolas Lamouroux ◽  
Jérémy Piffady ◽  
...  
Keyword(s):  
Water Temperature ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Hierarchical Bayesian ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Animal Populations ◽  
Brown Trout Salmo Trutta ◽  
Shelter Availability ◽  
Dependent Mortality

Successful management and protection of wild animal populations relies on good understanding of their life cycles. Because population dynamics depends on intricate interactions of biological and ecological processes at various scales, new approaches are needed that account for the variability of demographic processes and associated parameters in a hierarchy of spatial scales. A hierarchical Bayesian model for the resident brown trout (Salmo trutta) life cycle was built to assess the relative influence of local and general determinants of mortality. The model was fitted to an extensive data set collected in 40 river reaches, combining abundance and environmental data (hydraulics, water temperature). Density-dependent mortality of juveniles increased at low water temperatures and decreased with shelter availability. High water temperature increased density-dependent mortality in adults. The model could help to predict monthly juvenile and adult mortality under scenarios of global warming and changes in shelter availability due to habitat degradation or restoration.

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.

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