Variability in stream discharge and temperature: a preliminary assessment of the implications for juvenile and spawning Atlantic salmon

Tetzlaff, Doerthe; Soulsby, Chris; Youngson, A. F.; Gibbins, Chris; Bacon, P. J.; Malcolm, I. A.; Langan, Simon

doi:10.5194/hess-9-193-2005

Cited by 53 publications

(53 citation statements)

References 64 publications

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“…Welton et al, 1999). Based on the data period 1994, Tetzlaff et al (2005b concluded that discharges less than 0.3 m 3 s À1 inhibited access to the burn. The current analysis for a longer period showed minimum mean daily discharges for entry for each year ranging between 0.10 (1972) and 1.62 (1987) m 3 s À1 .…”

Section: Discussionmentioning

confidence: 99%

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Influence of hydrological regimes on the pre‐spawning entry of Atlantic salmon (Salmo salar L.) into an upland river

Tetzlaff

Gibbins

Bacon³

et al. 2008

River Research & Apps

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The Girnock Burn is an Atlantic salmon (Salmo salar) spawning tributary of the river Dee, Aberdeenshire, Scotland. The dates, sexes and numbers of adult salmon entering the stream in the three months prior to spawning were determined between 1969 and 2005 using a permanent fish-trap. During this time, the number of fish returning to spawn varied markedly. Here we analyze the whole of this unique long term data set in order to characterize and classify the hydrologic regimes of the pre-spawning migration period and assess the extent to which these regimes help explain the timing and patterns of arrival of adult salmon into the stream. A range of flow parameters was calculated for the arrival period (September-November) for each of the 37 years. These parameters were used to ordinate and classify years according to their flow regimes. The analysis yielded six distinct groups or 'flow regime types' which separated principally in relation to flow magnitude and frequency parameters. The number of fish entering the burn on a given day was not significantly correlated to discharge on that day. However, patterns of arrival of fish differed markedly between years with different regime types, with the number of fish arriving on a given day related to patterns of discharge over the preceding part of the arrival period. Overall inter-annual variability in entry corresponded to the defined regime types. In wetter years, fish entry to the stream usually starts relatively early and continues throughout the pre-spawning period. In contrast, dry years may result in fish entry being delayed; this may result in lower numbers of spawning females entering the stream and sub-optimal utilization of juvenile habitat in the following spring.

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Section: Discussionmentioning

confidence: 99%

“…Instantaneous discharges vary between ca. 0.04 m 3 s À1 in the summer (Malcolm et al, 2003) and > 30 m 3 s À1 during floods (Tetzlaff et al, 2005b). Most high discharge events occur between late autumn and early spring, though they can occur throughout the year (Tetzlaff et al, 2007a).…”

Section: Study Catchmentmentioning

confidence: 99%

Influence of hydrological regimes on the pre‐spawning entry of Atlantic salmon (Salmo salar L.) into an upland river

Tetzlaff

Gibbins

Bacon³

et al. 2008

River Research & Apps

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“…With climate change, an increased discharge during winter, spring and autumn was observed (Birsan et al 2005) and with the predicted advance of peak flows in spring (Jasper et al 2004;Horton et al 2006) the timing could overlap fry emergence. Fry, around the time of emergence, is considered to be the live stage most sensitive to high floods (Jensen and Johnsen 1999;Cattanéo et al 2002;Tetzlaff et al 2005) whereas egg scouring is thought to occur only with extreme events (Cattanéo et al 2002). However, only a slight increase in discharge could result in significant egg damage (Montgomery et al 1996) and high discharges during incubation time and emergence was found to be inversely related to year-class-strength of brown trout (DeVries 1997;Spina 2001;Cattanéo et al 2002).…”

Section: Effect Of Changes In Temperatures and High Discharge On Spawmentioning

confidence: 99%

Climate and land-use changes affecting river sediment and brown trout in alpine countries—a review

Scheurer

Alewell

Bänninger

et al. 2008

Environ Sci Pollut Res

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Background, aim, and scope Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated. Approach We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries.-Have climate change and land-use change increased erosion and sediment loads in rivers? -Do we have indications of an increase in riverbed clogging?-Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging?Results Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and prealpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish. Discussion Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades. Conclusions Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sedi...

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“…Furthermore, atmospheric warming in combination with projected reductions in summer flow is expected to increase river temperatures [10]. If we translate these impacts to potential consequences for the proliferation of the salmon, and thus the success of achieving related policy objectives, we obtain the following factors [30][31][32][33][34][35]:…”

Section: Step 2: Climate Impacts On Rhine Salmon Habitatsmentioning

confidence: 99%

Adaptation Turning Points in River Restoration? The Rhine Salmon Case

et al. 2013

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Abstract:Bringing a sustainable population of Atlantic salmon (Salmo salar) back into the Rhine, after the species became extinct in the 1950s, is an important environmental ambition with efforts made both by governments and civil society. Our analysis finds a significant risk of failure of salmon reintroduction because of projected increases in water temperatures in a changing climate. This suggests a need to rethink the current salmon reintroduction ambitions or to start developing adaptive action. The paper shows that the moment at which salmon reintroduction may fail due to climate change can only be approximated because of inherent uncertainties in the interaction between salmon and its environment. The added value of the assessment presented in this paper is that it provides researchers with a set of questions that are useful from a policy perspective (by focusing on the feasibility of a concrete policy ambition under climate change). Thus, it offers opportunities to supply policy makers with practical insight in the relevance of climate change.

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Variability in stream discharge and temperature: a preliminary assessment of the implications for juvenile and spawning Atlantic salmon

Cited by 53 publications

References 64 publications

Influence of hydrological regimes on the pre‐spawning entry of Atlantic salmon (Salmo salar L.) into an upland river

Influence of hydrological regimes on the pre‐spawning entry of Atlantic salmon (Salmo salar L.) into an upland river

Climate and land-use changes affecting river sediment and brown trout in alpine countries—a review

Adaptation Turning Points in River Restoration? The Rhine Salmon Case

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