A very formative report on the findings of last years scale sampling by Jamie Urquhart, River Don Trust Biologist can be read here
http://www.riverdon.org.uk/FileLibrary/PDF%20Reports/Scale%20Sampling%20Report%202010.pdf (http://www.riverdon.org.uk/FileLibrary/PDF%20Reports/Scale%20Sampling%20Report%202010.pdf)
That's an interesting read Iain, thanks for posting it. :D