The River Ayr is getting low and catches of smolts are slowing down. This week we have been catching quite large salmon smolts in the size range 130 to 165mm. The scales show that they are all two year olds. As the river is so low we think that these smolts will be from the lower river in the vicinity of the smolt trap. The upper river smolts will be smaller.
The smolts are now well advanced with silver scales, black fins and edge to the tail.
We found a large adult stonefly on the trap this morning, the first so far this year. This is likely to be Perlodes microcephala as we don’t normally find Perla bipunctata this far downstream on the Ayr, although they are abundant in the upper reaches where water quality is better.
Talking of water quality this was what the inside of the smolt box looked like this morning; full of dirty looking foam. 
There are various sewage treatment works upstream and lots of diffuse pollution sources and this sort of scummy foam is not unusual on the Ayr. Although to be fair water quality seems to be improving and the “chemically” smell which was present in the air down by the river seems a much less frequent occurance.
BS
