Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Jul 14;11(15):10207-10224.
doi: 10.1002/ece3.7827. eCollection 2021 Aug.

Higher growth variability and stronger responses to temperature changes in wild than hatchery-reared sea trout (Salmo trutta L.)

Adam M Lejk  1 , Szymon Smoliński  2 , Grzegorz Radtke  3 , Andrzej Martyniak  1   2   3
Affiliations

Higher growth variability and stronger responses to temperature changes in wild than hatchery-reared sea trout (Salmo trutta L.)

Adam M Lejk et al. Ecol Evol. .

Abstract

Each year, millions of hatchery-reared sea-run brown trout Salmo trutta L. (the sea trout) juveniles are released into the natural environment in the Atlantic region. The aim of this work was to investigate the growth responses of sea trout to changing temperature conditions and to compare the growth plasticity between wild and hatchery-reared fish. Scales were collected from sea trout in a selected river flowing into the southern Baltic Sea. We analyzed the scale increment widths as a proxy of somatic growth and investigated the interannual variabilities and differences in growth between fish groups (wild and hatchery-reared). We used mixed-effects Bayesian modeling and ascribed the variances in growth to different sources. Furthermore, we developed indices of interannual (2003-2015) growth variation in the marine and freshwater phases of the life cycle of the fish and analyzed the relationships between trout growth and temperature. Temperature positively affects fish growth, regardless of the origin of the fish. We observed stronger relationships between fish growth and temperature conditions in the marine phase than in the freshwater phase. Additionally, wild sea trout are characterized by stronger responses to temperature variability and higher phenotypic plasticity of growth than those of the hatchery-reared individuals. Therefore, wild sea trout might be better suited to changing environmental conditions than hatchery-reared sea trout. This knowledge identifies possible threats in management actions for sea trout with an emphasis on ongoing climate change.

Keywords: Baltic Sea; Bayesian mixed‐effects models; anadromous brown trout; fish; fish scales; sclerochronology.

PubMed Disclaimer

Conflict of interest statement

The authors have no conflicts of interest to declare.

Figures

FIGURE 1
FIGURE 1
Map of the study area with the indicated regions over which the surface temperature data were aggregated (dashed rectangles). The area of the zoomed‐in map is marked with a black polygon. The horizontal arrow indicates the location of fish sampling. The vertical arrow indicates the smolts’ stocking site
FIGURE 2
FIGURE 2
Relationships between the scale radius and fish fork length (FL). FL = 17.128 + 0.013 × scale radius, F 1,1594 = 4,789, R2 = 0.76, p < .001
FIGURE 3
FIGURE 3
Measurements of the growth increments of fish scales. Points and error bars indicate mean ± standard deviation. Fish are grouped by sea age (columns) and freshwater age (rows). The vertical line shows the transition from freshwater to marine ecosystems, and “FW” and “SW” on the x‐axis indicate the freshwater and sea age, respectively. SW + increments and increments formed during spawning events in repeating spawners were excluded from the plot
FIGURE 4
FIGURE 4
Interannual growth variation in sea trout in the freshwater (upper panel) and sea (lower panel) stages. The time series represent the posterior distribution (mean ± standard deviation) of the year random effects of the selected growth model
FIGURE 5
FIGURE 5
Posterior distribution of the growth model parameter estimates obtained with the Bayesian technique and integrated nested Laplace approximations. The points show the mean estimates, the bars indicate the confidence intervals, and the stars show effects that are considered important (when the 95% confidence interval (CI) of the parameter estimates does not overlap zero). For better visibility, estimates of the intercepts are omitted (6.70; CI = 6.66–6.74)
FIGURE 6
FIGURE 6
Distribution of the individual fish random intercepts estimated by the growth models
FIGURE 7
FIGURE 7
Correlations between freshwater (a) and sea (b) mean growth time series and mean monthly surface (skin) temperatures for both environments. Mean correlations are given with 95% confidence intervals (CIs). The points and error bars represent the means and standard deviations of the posterior distribution of the random year effects (index of growth variability). The transparent thin lines reflect 1,000 models obtained from Monte Carlo simulations considering uncertainty in the growth variation estimates using posterior distribution. The bolded thick lines represent the models fitted to the mean values of the posterior distribution
See this image and copyright information in PMC

References

    1. Aprahamian, M. W. , Smith, K. M. , McGinnity, P. , McKelvey, S. , & Taylor, J. (2003). Restocking of salmonids ‐ opportunities and limitations. Fisheries Research, 62, 11–227. 10.1016/S0165-7836(02)00163-7 - DOI
    1. Araki, H. , Berejikian, B. A. , Ford, M. J. , & Blouin, M. S. (2008). Fitness of hatchery‐reared salmonids in the wild. Evolutionary Applications, 1, 342–355. 10.1111/j.1752-4571.2008.00026.x - DOI - PMC - PubMed
    1. Araki, H. , & Schmid, C. (2010). Is hatchery stocking a help or harm? Evidence, limitations and future directions in ecological and genetic surveys. Aquaculture, 308, S2–S11. 10.1016/j.aquaculture.2010.05.036 - DOI
    1. Bartel, R. (2001). Return of salmon back to Polish waters. Ecohydrology & Hydrobiology, 1, 377–392.
    1. Bartel, R. , Ikonen, E. , & Auvinen, H. (2001). Differences in migration pattern and growth of Polish and Finnish sea trout (Salmo trutta L.) released in the same areas. Archives of Polish Fisheries, 9, 105–122.