An experimental field evaluation of winter carryover effects in semi‐anadromous brown trout (<i>Salmo trutta</i>)

Midwood, Jonathan D.; Larsen, Mette Voldby; Boel, Mikkel; Aarestrup, Kim; Cooke, Steven J.

doi:10.1002/jez.1955

Cited by 22 publications

(33 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, experiences during rearing, overwintering, and migration in the first habitat can result in changes in performance and survival in later life stages. The effects could involve physiological processes (Davy et al., ; McKinnon, Stanley, & Stutchbury, ; Midwood, Larsen, Boel, Aarestrup, & Cooke, ), genetic influences (Ceriani et al., ), and conservation practices (Holsman et al., ). Figure demonstrates the complexity of interactions.…”

Section: Discussionmentioning

confidence: 99%

Conservation planning for freshwater–marine carryover effects on Chinook salmon survival

Gosselin

Zabel

Anderson

et al. 2017

Ecology and Evolution

View full text Add to dashboard Cite

Experiences of migratory species in one habitat may affect their survival in the next habitat, in what is known as carryover effects. These effects are especially relevant for understanding how freshwater experience affects survival in anadromous fishes. Here, we study the carryover effects of juvenile salmon passage through a hydropower system (Snake and Columbia rivers, northwestern United States). To reduce the direct effect of hydrosystem passage on juveniles, some fishes are transported through the hydrosystem in barges, while the others are allowed to migrate in‐river. Although hydrosystem survival of transported fishes is greater than that of their run‐of‐river counterparts, their relative juvenile‐to‐adult survival (hereafter survival) can be less. We tested for carryover effects using generalized linear mixed effects models of survival with over 1 million tagged Chinook salmon, Oncorhynchus tshawytscha (Walbaum) (Salmonidae), migrating in 1999–2013. Carryover effects were identified with rear‐type (wild vs. hatchery), passage‐type (run‐of‐river vs. transported), and freshwater and marine covariates. Importantly, the Pacific Decadal Oscillation (PDO) index characterizing cool/warm (i.e., productive/nonproductive) ocean phases had a strong influence on the relative survival of rear‐ and passage‐types. Specifically, transportation benefited wild Chinook salmon more in cool PDO years, while hatchery counterparts benefited more in warm PDO years. Transportation was detrimental for wild Chinook salmon migrating early in the season, but beneficial for later season migrants. Hatchery counterparts benefited from transportation throughout the season. Altogether, wild fish could benefit from transportation approximately 2 weeks earlier during cool PDO years, with still a benefit to hatchery counterparts. Furthermore, we found some support for hypotheses related to higher survival with increased river flow, high predation in the estuary and plume areas, and faster migration and development‐related increased survival with temperature. Thus, pre‐ and within‐season information on local‐ and broad‐scale conditions across habitats can be useful for planning and implementing real‐time conservation programs.

show abstract

Section: Discussionmentioning

confidence: 99%

Conservation planning for freshwater–marine carryover effects on Chinook salmon survival

Gosselin

Zabel

Anderson

et al. 2017

Ecology and Evolution

View full text Add to dashboard Cite

show abstract

“…High cortisol levels may increase mortality, and, for example, brown trout with artificially elevated cortisol levels have reduced overwinter survival rates (Midwood et al, 2015). Lack of winter shelters has been shown to elevate metabolic rates, which has been suggested to be sustained by cortisol (Millidine et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Stress responses of juvenile brown trout under winter conditions in a laboratory stream

Watz

2017

Hydrobiologia

View full text Add to dashboard Cite

Winter can be a challenging period for fish in northern temperate rivers and streams, particularly in those that are channelized, structurally simple or regulated by, for instance, hydropower. In these systems, dynamic sub-surface ice formation commonly occurs and stable periods with ice cover may be short. Under these adverse conditions, access to shelters has been shown to be an important factor that influences overwinter survival, and exclusion from shelters by anchor ice may cause stress. Here, stress responses of juvenile brown trout under simulated winter conditions in an artificial stream were studied. Trout were subjected to three treatments in which the trout (1) were excluded from an instream wood shelter, simulating the effects of anchor ice, (2) had access to the shelter or (3) had surface ice cover in addition to the shelter. There was a positive correlation between ventilation frequency and plasma cortisol concentration. Trout without access to shelter had 30% higher ventilation frequency than trout with instream shelter and surface ice, but no differences in cortisol concentration or stress colour were found between the treatments. River regulation that reduces surface ice and increases anchor ice formation may lead to increased stress and consequently reduce overwinter survival rates.

show abstract

“…It is possible that the laboratory‐treatment was stressful for the fish, and a recent study have indicated that high stress levels in autumn may reduce over‐winter survival (Midwood et al. ). Laboratory‐treated fish may also have had difficulties in acclimating back to the stream environment, leading to poorer survival.…”

Section: Discussionmentioning

confidence: 99%

“…Fish that were kept in the laboratory for 1 month ('laboratory-treated', i.e., LR and HR) had generally lower recapture rates, indicating lower survival, as compared to STR fish. It is possible that the laboratory-treatment was stressful for the fish, and a recent study have indicated that high stress levels in autumn may reduce over-winter survival (Midwood et al 2015). Laboratory-treated fish may also have had difficulties in acclimating back to the stream environment, leading to poorer survival.…”

Section: Differences Between Fish Kept In the Laboratory And Stream Fishmentioning

confidence: 99%

Autumn food restriction reduces smoltification rate, but not over‐winter survival, in juvenile brown trout Salmo trutta

Näslund

Sundström

Johnsson

2015

Ecology of Freshwater Fish

View full text Add to dashboard Cite

The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we present the results of an over-winter field experiment where energy levels were manipulated in late autumn. Three groups of juvenile (age 1+) brown trout, from an anadromous population, were monitored with respect to over-winter growth rate and survival (as indicated by recapture rates). Two groups were fed either high (HR), or low (LR) food rations in the laboratory for a month (October); the third group remained in the stream (STR). Over-winter growth rates were relatively low in all groups, and no growth compensation could be detected. Compared to HR and LR, STR fish had higher recapture rates after winter, indicating that laboratory housing may have affected the subsequent stream survival negatively. Comparing the two laboratory-housed groups, the LR group reached similar condition as the HR group in early spring, without indications of differences in survival. However, the initiation rate of body silvering (indicating initiation of smoltification) was lower in the LR group.Thus, it appears that food restriction during late autumn affect the onset of smoltification in juvenile brown trout. The results support previous laboratory studies indicating that salmonids modify their over-winter foraging behaviour to avoid too low energy levels at the end of winter. This modification appears to delay smoltification, but may not necessarily be costly in terms of over-winter mortality.

show abstract

An experimental field evaluation of winter carryover effects in semi‐anadromous brown trout (Salmo trutta)

Cited by 22 publications

References 79 publications

Conservation planning for freshwater–marine carryover effects on Chinook salmon survival

Conservation planning for freshwater–marine carryover effects on Chinook salmon survival

Stress responses of juvenile brown trout under winter conditions in a laboratory stream

Autumn food restriction reduces smoltification rate, but not over‐winter survival, in juvenile brown trout Salmo trutta

Contact Info

Product

Resources

About