THE ‘BIG FOUR’ Scottish salmon rivers traditionally allowed anglers to cross the country and hit the prime fishing months alongside the changing of the seasons. First in the annual fishing calendar was the Dee from opening day in February through to the early spring, then across to the Spey in late spring and summer, down to the Tay for the big autumn run in September, and finally to Tweed for its famous ‘back end’ run in October and November. But the world has changed. Our seasons and climate seem increasingly out of balance, unpredictable and with more frequent extreme weather events. Where once winters would pack snow on to the hills and gently rising temperatures allowed for a gradual thaw in the spring, now increasingly winters are wet and wild with severe storms, large temperature fluctuations and significant flooding. In the spring and summer months, more regular droughts and heatwaves are experienced. Drought years are predicted to occur in one in every two years in the future, compared with the current UK average of five to 10 years.
What does athat salmon require cold, clean water to thrive, with the optimum in-river temperature for juvenile growth and feeding being around 16°C. Above that temperature, growth slows and by 22°C stops altogether. Young salmon are, of course, getting ready for a marathon – their epic ocean migration that will take some of them as far as Greenland – and evidence shows that the fitter our young salmon ‘smolts’ are when they leave our rivers, the more of them will come home as adults. Temperature and feeding in the freshwater environment is therefore critical to a salmon’s marine survival. You wouldn’t start a marathon on an empty stomach and nor should salmon.
