Smelt populations have been recorded since the 18th Century from at least 15 rivers in Scotland, but over the last Century the species has suffered a severe decline and has disappeared from all its former sites except the rivers Cree, Forth and Tay. These populations must now be regarded as having high conservation importance. There are probably several different reasons for this decline. In some rivers, such as the Clyde and the Stinchar, pollution in the lower reaches has prevented successful migration and reproduction. In other rivers, high weirs and barriers have completely cut off access to spawning grounds. In some estuaries and rivers, such as the Solway Firth, overfishing is believed to have been responsible for eliminating local stocks. A Species Action Plan for the smelt has been prepared and it is hoped that this will be the basis of a future conservation strategy for this species in Scotland.