River managers will be able to moderate the impact of climate change on Scotland's rivers and fisheries by using a new online mapping tool to plan mitigation work.
Scientists at Marine Scotland and the University of Birmingham have developed a river temperature model to predict the maximum daily river temperatures and sensitivity to climate change throughout Scotland, with interactive maps made available through the National Marine Plan interactive website.
Scotland's rivers account for around 75% of the UK and 30% of European wild salmon production, with freshwater fisheries and associated expenditure contributing more than £79 million a year to the Scottish economy.
However, with Atlantic salmon sensitive to changes in river temperature and temperatures expected to increase under climate change, there are concerns Scottish rivers could become less suitable in terms of habitat.
Professor David Hannah, UNESCO Chair in Water Science at the University of Birmingham's School of Geography, Earth and Environmental Science, said: 'River temperature is an important control on physical, chemical and biological processes in flowing waters. For freshwater ecology, river temperature influences strongly species distribution and abundance as well as individual's performance. Under climate change, it is anticipated that river temperature will increase - altering the thermal suitability of rivers for native species and increasing risks associated with invasive species.
'In collaboration with Marine Scotland, we have implemented a purpose designed river temperature monitoring network for Scotland. This Scotland River Temperature Monitoring Network (SRTMN) allows us to model where river temperature is hottest, as well as those locations where river temperature is most sensitive to climate change.
'This information is important for river management because it may be used to underpin climate change adaptation strategies (such as planting trees next to rivers to create shading) to reduce high temperature extremes that may be damaging for aquatic organisms.'
Environment Secretary Roseanna Cunningham said: "We know a number of complex factors, including climate change, are affecting wild salmon numbers in the north east Atlantic region.
"This research identifies areas where our famous salmon rivers are at risk due to climate change and will help fisheries managers target work to protect stocks and increase the resilience of our fresh waters.
"It is vital we take decisive action to safeguard wild salmon stocks and we will continue to work with Fisheries Management Scotland and their members to do so."
Alan Wells, Chief Executive of Fisheries Management Scotland said: "Scotland's Atlantic salmon populations are subject to a range of pressures and increases in freshwater temperature, associated with climate change, will increasingly need to be managed. Our member District Salmon Fishery Boards and Fisheries Trusts are engaged in projects to plant trees near rivers, in order to provide dappled shade and reduce extremes of temperature in our rivers. This model will be a valuable tool in targeting these efforts so that we can maximise the beneficial impact on our rivers."
Mark Bilsby from the River Dee Trust said: "This is a really useful piece of work as it will allow us to target our resources on those parts of river in most need of trees to create shade and bring the temperatures down. The practical measures of planting trees to offset the local impacts of warming temperatures is well proven and this will put them where they are most needed."
Simon McKelvey from the Cromarty Firth Fishery Board, said: "The Cromarty Firth Fishery Board, like many other fishery management organisations in Scotland has been undertaking a programme of native riparian woodland restoration for a number of years. The ecological benefits of riverside woodland are well recognised in terms of; nutrient input, sediment control, cover for wild fish and natural flood management. This work will allow us to plan planting to ensure that the maximum benefits from shading are also achieved."
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