Nearly all our still waters are currently suffering from drawdown. This translates to warm waters, or in some cases (ie; top end of Daniels), no water. Where water is shallow and therefore warm, fish have a lot tougher time reviving on release after being played for almost any length of time. Consider fishing the deepest still waters, or where springs enter, which are sure to be the coolest. It may take a type four sinking line to get down in the deep, but you will do a favor to any fish you catch by giving them a better survival rate.