Bristol Frome - Smoltification. You what?

Spent the evening, after the hottest day of the year so far, fishing for a few hours on my local stretch of the Bristol Frome. Fished my usual pools and caught one on the dry and one on the nymph. I saw about half a dozen rises but the fish seemed a bit fussy not rising or taking just any fly. Big surprise was that one of the fish I caught in the evening was what I can only describe as a Smolt. It was a small feisty trout on steroids that once in the net was clearly a distinct silver bar. The fins were semi transparent with a dark edge. Why would any wild Brownie some 10 miles upstream of the sea, above perhaps ten weirs, an underwater culvert, and the barrier of Bristol Docks ever think smoltification to go to sea was ever a good idea! Is it in the genes of the population that every now again one of the resident fish will go all the way and transform to a Sea Trout? It did make me think of one other fish I'd previously caught that was distinctly different in colouration that could have also had the urge but the case was not as clear cut as this one (see my post 21/5/2012).  I wished it well on its downward journey and would like to think it would one day attempt its mammoth journey back up to one of my favoured pools with some extra saline muscle to put a bend in my 3 weight! Likelyhood is it will 'slob' out with all the other party goers down at the waterfront feeding on bread for the swans in Bristol Docks never to return. The resilience of nature never ceases to amaze me.

Not a great shot but the silver is unmistakeable