Condition-dependent skipped spawning in anadromous brown trout (Salmo trutta)

2018 ◽  
Vol 75 (12) ◽  
pp. 2313-2319 ◽  
Author(s):  
Tormod Haraldstad ◽  
Erik Höglund ◽  
Frode Kroglund ◽  
Anders Lamberg ◽  
Esben Moland Olsen ◽  
...  
Keyword(s):  
Salmo Trutta ◽  
Fitness Landscape ◽  
Regulated Rivers ◽  
Sea Trout ◽  
Skipped Spawning ◽  
Return Probability ◽  
Management Perspective ◽  
Brown Trout Salmo Trutta ◽  
Post Spawning ◽  
Sea Survival

Repeat spawners of anadromous salmonids may contribute significantly to population resilience by providing multiple cohorts to both seawater and freshwater life stages. In this study, winter survival of sea trout (Salmo trutta Linnaeus, 1758) post spawners (kelts) was 89%. Sea survival increased linearly with female length with a return probability between 30% and 50%, whereas males attained a maximum return probability of 60% at 520 mm. Of the returning sea trout, 40% skipped spawning and they had significantly lower condition factor as kelts compared with those who returned after one summer. These results suggest that sex-specific differences in individual post-spawning growth–survival trade-off exist and that energetic status of descending kelts may influence the probability to skip spawning. We discuss to what extent hydropower may reduce post-spawning survival due to blocking of river descent opportunities, potentially altering the fitness landscape and favouring new life-history adaptations. From a management perspective, it is concluded that it is crucial to maintain connectivity in regulated rivers, allowing fish to complete repetitive spawning and feeding migrations, thus contributing to population productivity.

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.

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.

The post-spawning movements of migratory brown trout Salmo trutta L.

2005 ◽  
Vol 67 (3) ◽  
pp. 809-822 ◽  
Author(s):  
B. Bendall ◽  
A. Moore ◽  
V. Quayle
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Brown Trout Salmo Trutta ◽  
Post Spawning

scholarly journals Saltwater spawning grounds of sea-run brown trout (Salmo trutta) in tidal waters of a major Norwegian river

2021 ◽  
Author(s):  
Sven-Erik Gabrielsen ◽  
Robert J. Lennox ◽  
Tore Wiers ◽  
Bjørn T. Barlaup
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Pink Salmon ◽  
River Mouth ◽  
Competitive Balance ◽  
Spawning Grounds ◽  
Sea Trout ◽  
Spawning Areas ◽  
Brown Trout Salmo Trutta ◽  
Spawning Behaviour

AbstractSea-run brown trout (Salmo trutta) have a highly phenotypically plastic life history that allows them to be effective colonizers and competitors in freshwater. This paper documents a previously unknown spawning behaviour in a brackish, tidally influenced estuary 14 km from the mouth of the Vosso River, a major Atlantic salmon- and sea-run brown trout–producing river in western Norway. Putative spawning gravel was observed, and sea-run brown trout deposited eggs that hatched in April. Survival of recruits was high (> 95%) in the tidal spawning gravel. These areas are strongly tidally influenced with a peak of 23.17 psu recorded at the lowest spawning ground. The observation of spawning so far from the river mouth may be unique in such a system with a long estuary but provides important insight into the biology of sea trout. Invasion of pink salmon, also known to spawn in estuaries, may negatively affect the competitive balance of sea trout with other salmonids in rivers where sea trout populations rely on recruitment from these relatively extreme spawning areas. Restoration of estuaries that have been modified by dredging or channelization may be important to ensure quality and heterogenous habitat for sea trout spawning given that haline spawning grounds could contribute to population resilience.

scholarly journals A comparison of trends in population size and life history features of Atlantic salmon (Salmo salar) and anadromous and non-anadromous Brown trout (Salmo trutta) in a single catchment over 116 years

Hydrobiologia ◽  
2021 ◽  
Author(s):  
Colin E. Adams ◽  
Hannele M. Honkanen ◽  
Ellen Bryson ◽  
Isabel E. Moore ◽  
Malcolm MacCormick ◽  
...  
Keyword(s):  
Time Series ◽  
Atlantic Salmon ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Relative Proportion ◽  
Population Trends ◽  
Sea Trout ◽  
Salmon Population ◽  
Brown Trout Salmo Trutta ◽  
Long Time

AbstractWe use a long time series of catch abundance from a recreational fishery over 116 years to look for population trends in Atlantic salmon, and anadromous (sea trout) and non-anadromous (brown) trout for a single catchment, Loch Lomond, west central Scotland. Year strongly predicted variation in catches but catch effort did not meaningfully increase explained variation. Salmon showed periods of increasing and decreasing trends, for sea trout and brown trout there was an overall declining trend. Since 1952, Lomond salmon population trends differed from both wider Scotland and southern Europe, indicating that the Lomond population is partially buffered from drivers of change in salmon populations more widely. In contrast Lomond sea trout showed a similar declining trend to that of populations from the wider west of Scotland over this period. The Lomond populations showed some evidence of shorter-term cycling patterns; the drivers for which are unknown. Body size in salmon and sea trout declined but increased in brown trout; salmon returned to freshwater later, and the relative proportion of all caught trout that were anadromous increased across the time series. This study shows a long and protracted period of fundamental change to populations of these two species over 116 years.

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