Protecting cold-water adapted freshwater fish from high river temperature projected under climate change

fish river med

We have improved adaptation strategies and management practices to protect cold-water adapted freshwater fish (including wild salmon - worth £80M to the UK economy) from the harmful effects of high river water temperature projected under climate change. Through a highly successful collaboration with Marine Scotland and local fisheries organisations, we implemented the first-ever national-scale, quality-controlled river temperature monitoring network and developed new modelling techniques that underpin accessible online tools for decision-makers. These tools have guided riparian tree planting (to shade rivers) by fisheries and other natural resource managers.

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 Key researchers

David Hannah Formal smlDavid Hannah

School of Geography, Earth and Environmental Sciences

Professor of Climate Resilience

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About the project

We have advanced adaptation strategies and management practices to protect cold-water adapted freshwater fish (including wild salmon - worth £80M to the UK economy each year) from the effects of high river water temperature expected under climate change.

By applying the first-ever national-scale, river temperature monitoring network and translating new modelling techniques into simple online tools for decision-makers we have:

  • instigated widespread 'riparian' tree planting (to shade rivers) by fisheries and other natural resource managers
  • provided evidence for Scottish Parliament debate and policy conservation efforts through the North Atlantic Salmon Conservation Organisation (NASCO)
  • influenced replication of the same approach by Inland Fisheries Ireland
  • enhanced practitioner and public understanding of rivers’ climate sensitivity


Under climate change, it is anticipated that river water temperature will increase - reducing thermal suitability for cold-water adapted native fish and heightening risks from invasive species. Atlantic salmon and anadromous brown trout are iconic species of high economic and conservation value, which are often the focus of management action.

In recent years, fisheries management organisations have tried to protect rivers from the detrimental effects of high water temperature under current and future climate. Riparian tree planting (to shade rivers and cool waters) is a well-promoted management option. However, concerns have been raised about the lack of reliable underpinning evidence to identify: (a) where rivers will be hottest, (b) where river temperatures will change most, and (c) where riparian tree planting will have the greatest effects (targeted based on a and b).

Our research addressed directly these needs and was co-created, developed and translated into decision support tools in collaboration with the Scottish Government - Marine Scotland Science (MSS). 

More than 15 years of collaborations led by The University of Birmingham (Prof. David M. Hannah) and MSS (Dr Iain Malcolm) has provided insights about: controls on river water temperature (Hannah et al., 2004, 2008; Garner et al., 2015; Dugdale et al., 2018); space-time variability of river temperature patterns (Malcolm et al., 2004, 2008); opportunities for management interventions to avoid high temperature extremes; and potential climate change impacts on river temperature. 

Dr Grace Garner provided new fundamental process understanding of the heat and water exchange processes controlling river temperature under different riparian tree cover scenarios (Garner et al., 2014; 2017). This process-based modelling and scenario testing revealed the conditions under which riparian shading has maximum impact on water temperature at the river reach to sub-catchment scale.

In parallel, the CAMERAS Freshwater Monitoring Action Plan identified the need for a bespoke monitoring network across Scotland to improve understanding of river temperature at the larger (catchment to national) scales to inform resource management.

The University of Birmingham and and MSS designed and developed the Scotland River Temperature Monitoring Network (SRTMN) based on understanding from our earlier studies. Local fisheries organisations (supported by MSS) delivered the network, deploying and downloading 223 dataloggers across 13 catchments

Recognitions and Impact

Interventions (tools, leaflets and policy-related measures) have made a demonstrable difference in understanding future threats under climate change as well as associated potential socio-economic and biodiversity losses. 

SRTMN is the world’s first national-scale, strategically designed, quality-controlled river temperature modelling monitoring network. It responds to the needs highlighted by the Coordinated Agenda for Marine, Environment & Rural Affairs Scotland (CAMERAS) review of freshwater monitoring. It has become a fundamental component of adaptation efforts by the freshwater fisheries sector to combat the challenges of a changing climate. STRMN is managed full-time now by MSS by staff recruited from the original research programme. Outputs from SRTMN have been translated into interactive, online decision-making tools used by fisheries and other natural resource managers. 

It is now possible for resource managers to access Scotland-wide maps online through Marine Scotland’s National Marine Planning Interactive portal to identify parts of river catchments that are most likely to be impacted negatively by climate change. 

Research has direct influence on national land use and water management policies. The Marine Scotland Policy Team Leader, Salmon and Recreational Fisheries, has “committed that riparian shade will be increased in sensitive and appropriate water bodies, as identified by SRTMN, through collaborative projects undertaken by DSFBs [District Salmon Fisheries Boards] and/ or Fisheries Trusts and that we will seek to establish measurable, voluntary targets which local managers” and is “actively encouraging, including through the potential creation of a national funding scheme, local managers to use the [STRMN] outputs to prioritise riparian tree planting. Indeed, it has already been utilised in several catchment areas.”. These interventions will advance “key policy objective of… protection and enhancement of Scotland’s wild Atlantic salmon populations” as “SRTMN delivers a significant practical or ‘real word’ benefit to our [Salmon and Recreational Fisheries] work” 

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