From its source high up at Loch Spey the river descends 1,000ft to its mouth at Spey Bay, some 107 miles, the most productive fishing is known as Strathspey from Grantown on Spey to Spey Bay.  This descent leads to a good flow all season, which make fly fishing very exciting and gives high expectations on every cast.  The sport starts in early March and runs strong until September.

http://www.fishpal.com/Scotland/Spey/index.asp?dom=Spey