In my experience any fish, fresh from saltwater usually deposit scales everywhere.
The net,rod handle and skin always seem to get a few even when you don't handle them 
.
Not sure how long they need to be in freshwater before this starts to change, i'm not the biologist.
But i would love to know 
Jamie 
To me the scales are always an obvious indication of a fresh fish , if i don't notice them then i would be less sure i'd got it right even before checking.
Sandy
Hi there guys, thanks to Iain for drawing my attention to this aspect of the post, it's been an interesting read.
I would say that the fish that have been taken for ST are most likely to be well mended kelts, its still early for Don ST yet. Upon recent survey work we have seen Salmon kelts as far upstream as Alford (how do we know they were kelts, well they were tagged fish from the Hatchery work and the tags were visible in the low water) and until this weekend there has been no water to push them down, therefore i suspect the ST have taken that bit longer to get down the system as well as a result. It not unusual to get kelts right through April and into May but they are often in the past few seasons obviously kelts. If they have stayed in then the conditions for them have been very good, plenty of feeding and an open winter will help recondition these trout.
Other rivers such as the Tweed, where they have early ST i.e. Feb/March, scale reading has showed that they have fish heading out for a few months before returning again in early summer and fresh fish coming in at the same time as these are heading out. I must stress that this is main stem sampling and the ST have multiple tributaries from which they may have originated hence the diversity in life history strategies which we do not experience on the same scale here on the Don.
Sandy's point is very good fresh fish will always shed scales, those that are not as fresh will not shed them so readily, as for the exact timeline on which this change happens i'm not sure but i'll endeavour to find out.
The only way to be sure is to collect some scales and have them read, the difference between fresh fish and a kelts is quite marked.
I spoke to a few of the other forum members over the weekend and i would be delighted to have some input from any of you interested in collecting scales from fish. The Trust's scale programme has suffered from a lack of trout scales over the past few seasons and any help on this front will enable the Trust to learn more about the trout stock and therefore recommend management actions to the Board such as those relating to the conservation code, currently discussed in this thread.
Anyone interested please get in touch i hope to be hosting a scale sampling session at the Trust office shortly.
biologist@riverdon.org.uk
FYI
Funding is still being sought for the Invertebrate Programme, we've been unsuccessful with one funder but are still confident that we can source funding, will keep you informed of progress, thanks for your patience on this front.
Cheers Jamie
