Salmon plight

The River Tweed catchment, renowned for its Atlantic salmon and the significant contribution it makes to Scotland's multimillion-pound freshwater fishing economy, faces increasing threats from climate change. Elevated river water temperatures cause severe thermal stress to salmon, directly impacting their welfare and migratory behaviour.

Atlantic salmon are an iconic Scottish species and contribute significantly to the rural economy through tourism and employment. A Scotland-wide economic impact assessment of wild fisheries, including salmon, indicates a value of over £100 million and accounts for 4,300 full-time equivalent jobs. 

Despite their importance, Atlantic salmon are classified as ‘endangered’ in Great Britain, because of a 30-50% decline in populations since 2006. Wild Atlantic salmon are sensitive to environmental change, acting as an early-warning system for problems in the wider ecosystem, and river health is critical for their survival.

Salmon are adapted to cool waters, with the optimum temperature being between 6-18°C. Atlantic salmon exhibit thermal stress at approximately 23°C, with mortality occurring at approximately 30°C. Climate change projections by the Met Office indicate that the severe summer temperatures seen in 2018 - where an estimated 70% of Scottish rivers exceeded 23°C, could become a biennial occurrence by 2050.

This warming trend threatens the ongoing health and welfare of the Tweed's salmon stocks.

Logistical challenges

The legacy manual communications network was not suited for the new requirement of real-time operational data. Grundfos Telemetry 4G were specifically chosen to complement the existing infrastructure by filling the gap for real-time, lowlatency transmission, as upgrading the entire manual network was not financially viable.

To protect fish stocks, improve animal welfare and strategically target environmental interventions, the Foundation required:

• Near real-time data on river temperature to inform immediate management decisions, such as informing and advising angling behaviour during high-stress periods.
  
  
• Expanded water quality insight to understand the complex interactions between temperature, dissolved oxygen (DO), pH and turbidity.
  
  
• Scientific intelligence to effectively prioritise long-term climate-adaptation actions like riparian tree planting, which aims to shade river channels and reduce maximum summer temperatures.

Enhanced data integrity

To address this challenge, The Tweed Foundation integrated Grundfos Telemetry 4G units across three strategic sites in the Tweed catchment.

The Grundfos Telemetry 4G is a highly efficient, batterypowered device that transforms manual data collection into a near-real-time, remotely managed operation. Using the SDI-12 communication protocol, the units connect to multiple sensors to collect a comprehensive suite of water quality parameters:

• Site 1 and 2: Continuous monitoring of conductivity and temperature

• Site 3: Comprehensive monitoring of dissolved oxygen, pH, conductivity and temperature

Crucially, the units seamlessly transmit this data via an application processing interface (API) to The River Tweed Foundation’s custom app. This integration ensures anglers have immediate, actionable intelligence to guide their fishing times - demonstrating the public transparency and engagement enabled by the Grundfos solution.

Real-time data is critical year-round, enabling anglers to know when to fish - from avoiding mid-afternoon 20°C peaks in spring, to managing prolonged heat during July and August.

Salmon welfare

The deployment achieved several immediate and long-term benefits, including improved salmon welfare and management. The shift to live data allows the Foundation to trigger alarms and make time-critical decisions based on immediate thermal conditions.

By having instant visibility of rising temperatures, the Foundation can liaise with regulatory bodies to give advice and implement voluntary angling restrictions. This proactive approach will reduce the stress on salmon populations during critical high-temperature events, as well as directly improving quality of life and survival rates for the fish, helping maximise the numbers spawning.

Additionally, the expanded monitoring beyond just temperature, particularly the inclusion of DO, pH and conductivity, provides a more complete picture of aquatic ecosystem health. This data is also vital for contributing to the wider understanding of how controlled releases of water from reservoirs, along with intensive rainfall and heatwaves, affect the complex dynamics of water quality.

Economic value

Reliable, scientifically backed ecosystem management underpins the river’s reputation as a world-class salmon angling destination, ensuring that its economic and cultural value for Scotland remains protected.

Beyond immediate operational use, this expanded dataset is essential for studying the complex link between temperature and other water quality parameters, bolstering the Foundation's long-term scientific research.

Though the Foundation continues to expand its use of the real-time data, the initial success of the project has generated significant interest across the sector, leading to inquiries from other fisheries trusts and associated bodies about adopting similar real-time temperature and water quality monitoring solutions. The River Tweed Foundation and Grundfos have established a proven model for leveraging advanced telemetry to help in the conservation of salmon and trout.

The success on the River Tweed has created a blueprint for techled conservation that is now being exported to other critical catchments.

Safeguarding the River Oich

Seeking to replicate these gains in efficiency and data integrity, the Ness District Salmon Fishery Board (NDSFB) has adopted a similar approach to solve the unique hydrological challenges of the River Oich.

The River Oich, a vital 9km link between Loch Oich and Loch Ness, serves as a critical corridor for early spring salmon and endangered freshwater pearl mussels. Despite its ecological significance, the river is heavily influenced by abstraction for the Caledonian Canal and hydropeaking - rapid and frequent fluctuations in the water flow downstream of hydropower plants. These factors cause the river to fluctuate rapidly and unpredictably, creating a complex management challenge for NDSFB.

Prior to 2024, the Oich was the only major tributary in the Ness catchment lacking a dedicated monitoring station. Without realtime data, NDSFB Director Brian Shaw and his team were forced to manage the river reactively, often guessing when water levels would be safe or appropriate for essential biological surveys.

Integration and impact

The deployment of the Telemetry device in April 2024 marked a turning point for the Board’s operations. "The transition to digital monitoring was remarkably straightforward. The equipment was sent directly to us and installed by the NDSFB team themselves,” explains Shaw.

Beyond operational efficiency, the data serves a vital conservation purpose. Salmon and trout are cold-water species sensitive to high temperatures that are becoming increasingly common across Scotland. By tracking the Oich's thermal profile, which is currently buffered by the upstream lochs, the Board can verify the health of the habitat in real-time.

Proactive protection

The success of the Grundfos Telemetry trial has shifted the NDSFB’s perspective from reactive management to proactive safeguarding. With large-scale energy developments and construction projects planned within the catchment, the Board is already exploring Grundfos’s more advanced sensors to monitor a broader range of water quality parameters.

For Brian Shaw, the value of this independent data cannot be overstated. By having "the receipts" of the river’s health logged 24/7, the Board is better positioned to prevent environmental incidents before they happen, and ensure accountability if they do.